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1

Quantitative analytical electron microscopy of multiphase alloys.  

PubMed

In this paper, we present a technique for analysis of composition gradients, using an analytical electron microscope, within the primary phase of a two-phase alloy for the case where the second-phase particle size is similar to the size of the irradiated volume. If the composition difference between the two phases is large, the detected compositional fluctuations associated with varying phase fractions may mask any underlying composition gradient of the primary phase. The analysis technique was used to determine grain boundary chromium concentration gradients in a nickel-base superalloy, alloy X-750. The technique may also be of use in other alloy systems. PMID:2709131

Prybylowski, J; Ballinger, R; Elliott, C

1989-02-01

2

Quantitative high resolution electron microscopy of grain boundaries  

SciTech Connect

The {Sigma}11 (113)/[1{bar 1}0] symmetric tilt grain boundary has been characterized by high resolution transmission electron microscopy. The method by which the images are prepared for analysis is described. The statistics of the image data have been found to follow a normal distribution. The electron-optical imaging parameters used to acquire the image have been determined by nonlinear least-square image simulation optimization within the perfect crystal region of the micrograph. A similar image simulation optimization procedure is used to determine the atom positions which provide the best match between the experimental image and the image simulation.

Campbell, G.H., King, W.E., Cohen, D., Carter, C.B.

1996-12-12

3

Electron Microscopy.  

ERIC Educational Resources Information Center

|Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)|

Beer, Michael

1980-01-01

4

Microscopy Hacks: development of various techniques to assist quantitative nanoanalysis and advanced electron microscopy.  

PubMed

For development of advanced materials, characterization using a scanning transmission electron microscope (STEM) including analysis via X-ray energy-dispersive spectrometry and electron energy-loss spectrometry is essential. Recent advances in aberration-corrected instruments have offered large-scale data acquisition at a high resolution for limited acquisition times both in imaging and in analysis. Further advanced procedures are required to analyze such large-scale datasets more efficiently including quantification. In addition, more simplified tuning procedures are crucial to the best possible resolution in the latest aberration-corrected instruments. In this review article, several approaches to perform advanced electron microscopy, which the author has been developing with his colleague, are described as 'Microscopy Hacks'. These are (i) quantification and elemental/chemical-imaging procedures, (ii) advanced statistical approaches to handle large-scale datasets and (iii) instrument characterization and tuning procedures including the latest development of an ad hoc autotuning procedure for aberration-corrected STEM imaging. PMID:23515525

Watanabe, Masashi

2013-03-20

5

Is scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) quantitative?  

PubMed

Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) is a widely applied elemental microanalysis method capable of identifying and quantifying all elements in the periodic table except H, He, and Li. By following the "k-ratio" (unknown/standard) measurement protocol development for electron-excited wavelength dispersive spectrometry (WDS), SEM/EDS can achieve accuracy and precision equivalent to WDS and at substantially lower electron dose, even when severe X-ray peak overlaps occur, provided sufficient counts are recorded. Achieving this level of performance is now much more practical with the advent of the high-throughput silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS). However, three measurement issues continue to diminish the impact of SEM/EDS: (1) In the qualitative analysis (i.e., element identification) that must precede quantitative analysis, at least some current and many legacy software systems are vulnerable to occasional misidentification of major constituent peaks, with the frequency of misidentifications rising significantly for minor and trace constituents. (2) The use of standardless analysis, which is subject to much broader systematic errors, leads to quantitative results that, while useful, do not have sufficient accuracy to solve critical problems, e.g. determining the formula of a compound. (3) EDS spectrometers have such a large volume of acceptance that apparently credible spectra can be obtained from specimens with complex topography that introduce uncontrolled geometric factors that modify X-ray generation and propagation, resulting in very large systematic errors, often a factor of ten or more. PMID:22886950

Newbury, Dale E; Ritchie, Nicholas W M

2012-08-09

6

Quantitative characterization of the mesothelioma-inducing erionite series minerals by transmission electron microscopy and energy dispersive spectroscopy.  

PubMed

Air-collected erionite series minerals from Cappadocia region of Turkey were characterized quantitatively by using transmission electron microscopy (TEM) equipped with energy dispersive spectroscopy (EDS). Field emission scanning electron microscopy aided identification of fibrous minerals. Quantitative characterization guidelines for positive identification of erionites proposed by Dogan and Dogan (2008) was applied and the modified balance error formula (E%<10) and Mg-content test <0.80 were performed for each analysis. Erionite species computation showed that the mineral is erionite-K and a mean chemical formula is proposed based upon the TEM-EDS results. Among the 60 analyses, 11 passed E% test (18.3%), 33 passed Mg-content test (55.0%), and only 3 passed both E% and Mg-content tests (5.0%). This shows difficulty of quantitative characterization of the erionite series minerals. However, as erionite is the most carcinogenic mineral known and is classified by IARC as a Group-I (human) carcinogen, it requires special attention from the mineralogical community to help establish its true mineralogical properties. Quantitatively characterized erionite data are very scarce in literature. Correctly identified erionite mineral types will be useful to medical researchers in their search to find a possible cure for the deadly disease of mesothelioma. PMID:21866558

Dogan, Meral

2011-08-22

7

Scanning electron microscopy of growing dental plaque: a quantitative study with different mouth rinses.  

PubMed

The aim of this study was to quantify the influence of different mouth rinses on dental plaque. Wearing splints with enamel pieces 24 volunteers rinsed with essential oils, amine/stannous fluoride, or chlorhexidine digluconate (0.12%) mouth rinses. After 24, 48, 72, and 96 h the enamel pieces were analyzed by scanning electron microscopy. The counts of cocci and bacilli in different plaque layers and the plaque thickness were almost similar using essential oils and amine/stannous fluoride. These results differed significantly from those of chlorhexidine digluconate mouth rinses. The results for plaque thickness were without significant differences between the groups at any appointment. PMID:23758106

Jentsch, Holger; Mozaffari, Eshan; Jonas, Ludwig

2013-06-12

8

Sub-0.1 nm-resolution quantitative scanning transmission electron microscopy without adjustable parameters  

SciTech Connect

Atomic-resolution imaging in the scanning transmission electron microscope (STEM) constitutes a powerful tool for nanostructure characterization. Here, we demonstrate the quantitative interpretation of atomic-resolution high-angle annular dark-field (ADF) STEM images using an approach that does not rely on adjustable parameters. We measure independently the instrumental parameters that affect sub-0.1 nm-resolution ADF images, quantify their individual and collective contributions to the image intensity, and show that knowledge of these parameters enables a quantitative interpretation of the absolute intensity and contrast across all accessible spatial frequencies. The analysis also provides a method for the in-situ measurement of the STEM's effective source distribution.

Dwyer, C. [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Department of Materials Engineering, Monash University, Victoria 3800 (Australia); ARC Centre of Excellence for Design in Light Metals, Monash University, Victoria 3800 (Australia); Maunders, C. [Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Zheng, C. L. [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Weyland, M.; Etheridge, J. [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Tiemeijer, P. C. [FEI Electron Optics, P.O. Box 80066, 5600 KA Eindhoven (Netherlands)

2012-05-07

9

Quantitative evanescent microwave microscopy  

NASA Astrophysics Data System (ADS)

A vast variety of measurement techniques with high spatial resolution exist. However, a nondestructive technique that provides reliable, sensitive measurements of the complex electrical impedance with high spatial resolution was lacking. I contributed to the development of such a novel microscope, namely scanned evanescent microwave probe (SEMP). We developed experimental and theoretical methods for the evaluation of microwave complex impedance, which allows the quantitative imaging of the complex microwave dielectric constant (for insulators) and resistivity (for conductors) on a submicron length scale. In order to improve the spatial resolution and reduce the sample or tip damages, we also developed a means of distance regulation. With future improvement of the technique, resolutions approaching 20 nm may be expected. The microscope allows the measurement of variations in sample electronic properties on microscopic length scales. We demonstrated the capability to image samples varying from superconducting structures, semiconductors to ferroelectric materials. Such microscopes should find broad applications in various scientific areas and the semiconductor industry.

Duewer, Frederick William

2000-10-01

10

Correlative fractography: combining scanning electron microscopy and light microscopes for qualitative and quantitative analysis of fracture surfaces.  

PubMed

Correlative fractography is a new expression proposed here to describe a new method for the association between scanning electron microscopy (SEM) and light microscopy (LM) for the qualitative and quantitative analysis of fracture surfaces. This article presents a new method involving the fusion of one elevation map obtained by extended depth from focus reconstruction from LM with exactly the same area by SEM and associated techniques, as X-ray mapping. The true topographic information is perfectly associated to local fracture mechanisms with this new technique, presented here as an alternative to stereo-pair reconstruction for the investigation of fractured components. The great advantage of this technique resides in the possibility of combining any imaging methods associated with LM and SEM for the same observed field from fracture surface. PMID:23402567

Hein, Luis Rogerio de Oliveira; de Oliveira, José Alberto; de Campos, Kamila Amato

2013-02-12

11

Quantitative characterization of nanoparticles in blood by transmission electron microscopy with a window-type microchip nanopipet.  

PubMed

Transmission electron microscopy (TEM) is a unique and powerful tool for observation of nanoparticles. However, due to the uneven spatial distribution of particles conventionally dried on copper grids, TEM is rarely employed to evaluate the spatial distribution of nanoparticles in aqueous solutions. Here, we present a microchip nanopipet with a narrow chamber width for sorting nanoparticles from blood and preventing the aggregation of the particles during the drying process, enabling quantitative analysis of their aggregation/agglomeration states and the particle concentration in aqueous solutions. This microchip is adaptable to all commercial TEM holders. Such a nanopipet proves to be a simple and convenient sampling device for TEM image-based quantitative characterization. PMID:22816618

Tai, Lin-Ai; Kang, Yu-Ting; Chen, Yu-Ching; Wang, Yu-Chao; Wang, Yu-Jing; Wu, Yu-Ting; Liu, Kuo-Liang; Wang, Chiu-Yen; Ko, Yu-Feng; Chen, Ching-Ya; Huang, Nai-Chun; Chen, Jen-Kun; Hsieh, Yong-Fen; Yew, Tri-Rung; Yang, Chung-Shi

2012-07-20

12

Quantitative characterization of agglomerates and aggregates of pyrogenic and precipitated amorphous silica nanomaterials by transmission electron microscopy  

PubMed Central

Background The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous silicon dioxide (SAS), or silica, NM. Results Bright field (BF) TEM combined with systematic random imaging and semi-automatic image analysis allows measuring the properties of SAS NM quantitatively. Automation allows measuring multiple and arithmetically complex parameters simultaneously on high numbers of detected particles. This reduces operator-induced bias and assures a statistically relevant number of measurements, avoiding the tedious repetitive task of manual measurements. Access to multiple parameters further allows selecting the optimal parameter in function of a specific purpose. Using principle component analysis (PCA), twenty-three measured parameters were classified into three classes containing measures for size, shape and surface topology of the NM. Conclusion The presented method allows a detailed quantitative characterization of NM, like dispersions of precipitated and pyrogenic SAS based on the number-based distributions of their mean diameter, sphericity and shape factor.

2012-01-01

13

Characterization of individual submicrometer aerosol particles collected in Incheon, Korea, by quantitative transmission electron microscopy energy-dispersive X-ray spectrometry  

Microsoft Academic Search

For the last decade the Monte Carlo calculation method has been proven to be an excellent tool for accurately simulating electron-solid interactions in atmospheric individual particles of micrometer size. Although it was designed for application to scanning electron microscopy, in the present study it is demonstrated that the Monte Carlo calculation can also be applied in a quantitative single particle

Hong Geng; Sujin Kang; Hae-Jin Jung; Marie Choël; HyeKyeong Kim; Chul-Un Ro

2010-01-01

14

Faults and foibles of quantitative scanning electron microscopy/energy dispersive x-ray spectrometry (SEM/EDS)  

NASA Astrophysics Data System (ADS)

Scanning electron microscopy with energy dispersive x-ray spectrometry (SEM/EDS) is a powerful and flexible elemental analysis method that can identify and quantify elements with atomic numbers > 4 (Be) present as major constituents (where the concentration C > 0.1 mass fraction, or 10 weight percent), minor (0.01<= C <= 0.1) and trace (C < 0.01, with a minimum detectable limit of ~+/- 0.0005 - 0.001 under routine measurement conditions, a level which is analyte and matrix dependent ). SEM/EDS can select specimen volumes with linear dimensions from ~ 500 nm to 5 ?m depending on composition (masses ranging from ~ 10 pg to 100 pg) and can provide compositional maps that depict lateral elemental distributions. Despite the maturity of SEM/EDS, which has a history of more than 40 years, and the sophistication of modern analytical software, the method is vulnerable to serious shortcomings that can lead to incorrect elemental identifications and quantification errors that significantly exceed reasonable expectations. This paper will describe shortcomings in peak identification procedures, limitations on the accuracy of quantitative analysis due to specimen topography or failures in physical models for matrix corrections, and quantitative artifacts encountered in xray elemental mapping. Effective solutions to these problems are based on understanding the causes and then establishing appropriate measurement science protocols. NIST DTSA II and Lispix are open source analytical software available free at www.nist.gov that can aid the analyst in overcoming significant limitations to SEM/EDS.

Newbury, Dale E.; Ritchie, Nicholas W. M.

2012-05-01

15

In-situ gas study and 3D quantitation of titania photocatalysts by advanced electron microscopy  

NASA Astrophysics Data System (ADS)

Titanium dioxide (TiO2) with metal nanoparticles exhibits a high photocatalytic activity by a charge separation. Recently the size of the nanoparticles has been reduced to less than 1 nm. In contrast, the size of TiO2 support particles has been kept at sub-micron sizes to ensure stability for practical use at high temperatures. For visualizing and analyzing the metal nanoparticles which are supported on different positions of those complex substrates, a high voltage transmission electron microscope(HVEM) shows a strong performance because of its high transmission capability to view whole areas of the catalysts. Electron tomography is also important to quantify the three-dimensional morphology such as size, density, surface area and nearest particle distance. Here we report the data obtained by using He-cooled 3D TEM/STEM, a newly developed 1MV high voltage environmental TEM/STEM and a 200kV aberration corrected TEM/STEM. Nanostructures of catalytic samples are characterized using these EMs as well as measurement of their chemical activity.

Tanaka, N.; Yoshida, K.; Arai, S.

2012-07-01

16

Quantitative multivariate data analysis in the examination of small signals from scanning transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Technological advancements have recently allowed scanning transmission electron microscopes (STEMs) to directly image atomic structures with better than 1 angstrom lateral resolution. Though the images contain chemical information about the sample through the relation of atomic number and thickness to image brightness, easy quantification of sample content using STEM images has remained elusive. This has been primarily due to the image imperfections caused by microscope instabilities, damaged or overly thick samples, or noise inherent in the high-angle annular dark field (HAADF) imaging technique. With recent increases in beam current, atomic resolution electron energy loss spectroscopic (EELS) mapping has made quantification possible over relatively large areas. However, the areas are still quite small in comparison to STEM images and require significantly greater acquisition times. This has excluded EELS from application to atomic-resolution quantification of beam-sensitive materials and limited the already minute sample volume studied in the STEM. This thesis has aimed to develop data analysis techniques that enhance the direct quantification of data extracted from HAADF-STEM images. Multivariate data analysis provided a means of studying correlated variations in image intensities, and was explored for application to the simple mass-thickness contrast of HAADF-STEM images. In this thesis, it is shown through image simulation that multivariate data analysis derives a linear relationship between the known sample composition and image intensity changes. The linear relationship is in the form of eigenimages and scores. Eigenimages correspond to characteristic intensity variations across many images. Scores relate the extent to which a characteristic intensity variation occurs in a particular image. These relationships can be derived many different ways, including principle component analysis, correspondence analysis, and independent component analysis. The method and implementation of these analyses are demonstrated on experimental data, giving local point defect information arising only from intensity variation. Calibration using simulated images allows quantification of individual column occupations.

Sarahan, Michael Carl

17

A quantitative X-ray diffraction and analytical electron microscopy study of service-exposed 2.25Cr–1Mo steels  

Microsoft Academic Search

2.25Cr–1Mo power plant headers, with exposures spanning the as-installed condition through to 190,000 h, have been characterised with analytical transmission electron microscopy and quantitative X-ray diffraction. Microscopy revealed a number of service-induced changes including M2C development within pro-eutectoid ferrite, and its dissolution along prior austenite grain boundaries. Carbide coarsening and development of Mo- and Cr-rich carbide phases were also apparent

D. R. G Mitchell; C. J Ball

2001-01-01

18

Quantitative investigation of surface and subsurface fatigue cracks near rivets in riveted joints using acoustic, electron and optical microscopy  

NASA Astrophysics Data System (ADS)

Using scanning acoustic microscopy, optical microscopy and scanning electron microscopy, in conjunction with fractography of fractured surfaces, the crack formation and growth kinetics of subsurface fatigue cracks and surface breaking fatigue cracks near rivets have been characterized in detail in this research. The scanning acoustic microscope was used to quantitatively investigate subsurface fatigue cracks (even when they were very small) at and near countersunk rivets in riveted lap joint specimens that are similar to the riveted lap joints found in the fuselages of many aircraft. It was found that the maximum nominal applied stress influences the fatigue crack initiation and propagation behavior. Eyebrow type cracks develop at lower stresses and centerline cracks develop at higher stresses. At low stress ranges, the fatigue cracks initiate a short distance from the rivet at or near the hidden surface of the chamfered panel. At higher stress amplitudes, the cracks initiate at the blunt knife edge. Residual compressive stresses and fretting are suggested to play more important roles at lower stress ranges. Both types of cracks initiate in a shear mode but transform to tensile, mode I, cracks as they grow. This transition occurs much more rapidly at the higher stress amplitude. At both high and low stresses, the cracks are longer on the fayed surface of the panel than elsewhere. In a comparison of Alclad 2024-T3 and Alclad 2524-T3, it was found that the high purity aluminum alloy 2524 nucleates cracks at a greater number of cycles than the less pure aluminum alloy 2024. At high stress, crack initiation plays less of a roll and the 2024 alloy has a longer life. The scanning acoustic microscope enabled us to study subsurface fatigue cracks. The understanding gained from the characterization of the subsurface fatigue cracks will help in the modeling of crack initiation and growth in the riveted lap joint and will also aid in the improvement of NDE techniques for the detection of these cracks. This novel technique for examining subsurface cracks will be useful in the study of subsurface cracks in other alloys.

Connor, Zayna Marie

2000-10-01

19

QEMSCAN° (Quantitative Evaluation of Minerals by Scanning Electron Microscopy): capability and application to fracture characterization in geothermal systems  

NASA Astrophysics Data System (ADS)

Fractures are important conduits for fluids in geothermal systems, and the creation and maintenance of fracture permeability is a fundamental aspect of EGS (Engineered Geothermal System) development. Hydraulic or chemical stimulation techniques are often employed to achieve this. In the case of chemical stimulation, an understanding of the minerals present in the fractures themselves is desirable to better design a stimulation effort (i.e. which chemical to use and how much). Borehole televiewer surveys provide important information about regional and local stress regimes and fracture characteristics (e.g. fracture aperture), and XRD is useful for examining bulk rock mineralogy, but neither technique is able to quantify the distribution of these minerals in fractures. QEMSCAN° is a fully-automated micro-analysis system that enables quantitative chemical analysis of materials and generation of high-resolution mineral maps and images as well as porosity structure. It uses a scanning electron microscopy platform (SEM) with an electron beam source in combination with four energy-dispersive X-ray spectrometers (EDS). The measured backscattered electron and electron-induced secondary X-ray emission spectra are used to classify sample mineralogy. Initial applications of QEMSCAN° technology were predominantly in the minerals industry and application to geothermal problems has remained limited to date. In this pilot study, the potential application of QEMSCAN° technology to fracture characterization was evaluated using samples of representative mineralized fractures in two geothermal systems (Newberry Volcano, Oregon and Brady's geothermal field, Nevada). QEMSCAN° results were compared with XRD and petrographic techniques. Nine samples were analyzed from each field, collected from the drill core in the 1000-1500 m depth range in two shallow wells (GEO-N2 at Newberry Volcano and BCH-3 at Brady's). The samples were prepared as polished thin sections for QEMSCAN° analysis. Results indicate that a sampling resolution of 10 ?m is sufficient to resolve fracture morphology and mineral zonation (where multiple episodes of mineralization occurred), and enables relatively fast data acquisition (3 cm2 can be analyzed in approximately 3 hours). Finer resolutions (down to 2.5 ?m) take significantly longer, but can be used to provide additional spatial detail in areas of interest after a low resolution (10 ?m) scan. Use of XRD data in conjunction with QEMSCAN° data is sometimes needed to distinguish geothermal alteration minerals with similar chemical compositions (clay minerals, micas and chlorite), however overall the technique appears to have excellent potential for geothermal applications.

Ayling, B.; Rose, P. E.; Zemach, E.; Drakos, P. S.; Petty, S.

2011-12-01

20

Electron microscopy of sillenites  

NASA Astrophysics Data System (ADS)

In this undergraduate project, the student performed transmission and scanning electron microscopy measurements on two sillenite compounds: Bi12SiO20 and Bi25InO39. To our knowledge, the electron diffraction patterns of sillenites have not been reported in the literature before. Our preliminary results show that both the tetravalent and trivalent compound have the sillenite structure. Using concepts from undergraduate solid state physics, the student will explain how the electron diffraction patterns were analyzed.

Scurti, Craig; Auvray, Nicolas; Lufaso, Michael; Kohno, Hideo; Arenas, Daniel

2013-03-01

21

Analysis of Transient Polyhydroxybutyrate Production in Wautersia eutropha H16 by Quantitative Western Analysis and Transmission Electron Microscopy  

PubMed Central

Polyhydroxybutyrates (PHBs) are polyoxoesters generated from (R)3-hydroxybutyryl coenzyme A by PHB synthase. During the polymerization reaction, the polymers undergo a phase transition and generate granules. Wautersia eutropha can transiently accumulate PHB when it is grown in a nutrient-rich medium (up to 23% of the cell dry weight in dextrose-free tryptic soy broth [TSB]). PHB homeostasis under these growth conditions was examined by quantitative Western analysis to monitor the proteins present, their levels, and changes in their levels over a 48-h growth period. The proteins examined include PhaC (the synthase), PhaP (a phasin), PhaR (a transcription factor), and PhaZ1a, PhaZ1b, and PhaZ1c (putative intracellular depolymerases), as well as PhaZ2 (a hydroxybutyrate oligomer hydrolase). The results show that PhaC and PhaZ1a were present simultaneously. No PhaZ1b or PhaZ1c was detected at any time throughout growth. PhaZ2 was observed and exhibited an expression pattern different from that of PhaZ1a. The levels of PhaP changed dramatically and corresponded kinetically to the levels of PHB. Transmission electron microscopy (TEM) provided the dimensions of the average cell and the average granule at 4 h and 24 h of growth (J. Tian, A. J. Sinskey, and J. Stubbe, J. Bacteriol. 187:3814-3824, 2005). This information allowed us to calculate the amount of each protein and number of granules per cell and the granule surface coverage by proteins. The molecular mass of PHB (106 Da) was determined by dynamic light scattering at 4 h, the time of maximum PHB accumulation. At this time, the surface area of the granules was maximally covered with PhaP (27 to 54%), and there were one or two PhaP molecules/PHB chain. The ratio of PHB chains to PhaC was ?60, which required reinitiation of polymer formation on PhaC. The TEM studies of wild-type and ?phaR strains in TSB provided further support for an alternative mechanism of granule formation (Tian et al., J. Bacteriol. 187:3814-3824, 2005).

Tian, Jiamin; He, Aimin; Lawrence, Adam G.; Liu, Pinghua; Watson, Nicki; Sinskey, Anthony J.; Stubbe, JoAnne

2005-01-01

22

Scanning Electron Microscopy, Inc  

Microsoft Academic Search

A cloned nontumorigenic control cell line of C3H mouse embryo cells (C3H\\/10T1\\/2CL8) and two cell lines derived from it by treatment in vitro with 7,12-dimethylbenz(a)anthracene (DMBA) or 3-methylcholanth rene (MCA) were studied by scanning electron microscopy. Confluent control cells were polygonal in shape and extensively flattened with smooth surfaces. Both in vitro transformants were pleomorphic to fusiform in shape, thicker

J. D. Fairing; LINDA E. MALICK; ROBERT LANGENBACH

1978-01-01

23

Electronic detectors for electron microscopy.  

PubMed

Electron microscopy (EM) is an important tool for high-resolution structure determination in applications ranging from condensed matter to biology. Electronic detectors are now used in most applications in EM as they offer convenience and immediate feedback that is not possible with film or image plates. The earliest forms of electronic detector used routinely in transmission electron microscopy (TEM) were charge coupled devices (CCDs) and for many applications these remain perfectly adequate. There are however applications, such as the study of radiation-sensitive biological samples, where film is still used and improved detectors would be of great value. The emphasis in this review is therefore on detectors for use in such applications. Two of the most promising candidates for improved detection are: monolithic active pixel sensors (MAPS) and hybrid pixel detectors (of which Medipix2 was chosen for this study). From the studies described in this review, a back-thinned MAPS detector appears well suited to replace film in for the study of radiation-sensitive samples at 300 keV, while Medipix2 is suited to use at lower energies and especially in situations with very low count rates. The performance of a detector depends on the energy of electrons to be recorded, which in turn is dependent on the application it is being used for; results are described for a wide range of electron energies ranging from 40 to 300 keV. The basic properties of detectors are discussed in terms of their modulation transfer function (MTF) and detective quantum efficiency (DQE) as a function of spatial frequency. PMID:21524337

Faruqi, A R; McMullan, G

2011-04-28

24

Bridging fluorescence microscopy and electron microscopy  

PubMed Central

Development of new fluorescent probes and fluorescence microscopes has led to new ways to study cell biology. With the emergence of specialized microscopy units at most universities and research centers, the use of these techniques is well within reach for a broad research community. A major breakthrough in fluorescence microscopy in biology is the ability to follow specific targets on or in living cells, revealing dynamic localization and/or function of target molecules. One of the inherent limitations of fluorescence microscopy is the resolution. Several efforts are undertaken to overcome this limit. The traditional and most well-known way to achieve higher resolution imaging is by electron microscopy. Moreover, electron microscopy reveals organelles, membranes, macromolecules, and thus aids in the understanding of cellular complexity and localization of molecules of interest in relation to other structures. With the new probe development, a solid bridge between fluorescence microscopy and electron microscopy is being built, even leading to correlative imaging. This connection provides several benefits, both scientifically as well as practically. Here, I summarize recent developments in bridging microscopy.

2008-01-01

25

Electronic detectors for electron microscopy.  

PubMed

Due to the increasing popularity of electron cryo-microscopy (cryoEM) in the structural analysis of large biological molecules and macro-molecular complexes and the need for simple, rapid and efficient readout, there is a persuasive need for improved detectors. Commercial detectors, based on phosphor/fibre optics-coupled CCDs, provide adequate performance for many applications, including electron diffraction. However, due to intrinsic light scattering within the phosphor, spatial resolution is limited. Careful measurements suggest that CCDs have superior performance at lower resolution while all agree that film is still superior at higher resolution. Consequently, new detectors are needed based on more direct detection, thus avoiding the intermediate light conversion step required for CCDs. Two types of direct detectors are discussed in this review. First, there are detectors based on hybrid technology employing a separate pixellated sensor and readout electronics connected with bump bonds-hybrid pixel detectors (HPDs). Second, there are detectors, which are monolithic in that sensor and readout are all in one plane (monolithic active pixel sensor, MAPS). Our discussion is centred on the main parameters of interest to cryoEM users, viz. detective quantum efficiency (DQE), resolution or modulation transfer function (MTF), robustness against radiation damage, speed of readout, signal-to-noise ratio (SNR) and the number of independent pixels available for a given detector. PMID:17913494

Faruqi, A R; Henderson, R

2007-10-29

26

Structure, ordering, and surfaces of Pt-Fe alloy catalytic nanoparticles from quantitative electron microscopy and X-ray diffraction  

NASA Astrophysics Data System (ADS)

The current challenge in catalyst development is to produce highly active and economical catalysts. This challenge cannot be overcome without an accurate understanding of catalyst structure, surfaces and morphology as the catalytic reactions occur on the surface active sites. Transmission Electron Microscopy (TEM) is an excellent tool for understanding the structures of the nanoparticles down to the atomic level in determining the relationship with the catalyst's performance in fuel cell applications. This paper describes a detailed structural characterization of Pt-Fe nanoparticles using aberration corrected TEM. Detailed analysis regarding the morphology, structural ordering, facets, nature of the surfaces, atomic displacements and compositions was carried out and presented in the context of their electrochemical performances. In addition, the effects of electrochemical cycling in terms of morphology and composition evolution of the nanoparticles were analyzed. Lastly, along with data from X-ray diffractometry, two different crystallographic models of the unknown Pt3Fe2 nanoparticle phase are proposed. The detailed characterization by TEM provides useful insights into the nanoparticle chemistry and structure that contributes to catalyst development for next generation fuel cells.The current challenge in catalyst development is to produce highly active and economical catalysts. This challenge cannot be overcome without an accurate understanding of catalyst structure, surfaces and morphology as the catalytic reactions occur on the surface active sites. Transmission Electron Microscopy (TEM) is an excellent tool for understanding the structures of the nanoparticles down to the atomic level in determining the relationship with the catalyst's performance in fuel cell applications. This paper describes a detailed structural characterization of Pt-Fe nanoparticles using aberration corrected TEM. Detailed analysis regarding the morphology, structural ordering, facets, nature of the surfaces, atomic displacements and compositions was carried out and presented in the context of their electrochemical performances. In addition, the effects of electrochemical cycling in terms of morphology and composition evolution of the nanoparticles were analyzed. Lastly, along with data from X-ray diffractometry, two different crystallographic models of the unknown Pt3Fe2 nanoparticle phase are proposed. The detailed characterization by TEM provides useful insights into the nanoparticle chemistry and structure that contributes to catalyst development for next generation fuel cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31509b

Chan, Mickey C. Y.; Chen, Liang; Nan, Feihong; Britten, James F.; Bock, Christina; Botton, Gianluigi A.

2012-10-01

27

Musculoskeletal responses of 2-year-old Thoroughbred horses to early training. 8. Quantitative back-scattered electron scanning electron microscopy and confocal fluorescence microscopy of the epiphysis of the third metacarpal bone  

Microsoft Academic Search

AIM: To characterise and explain the increase in density evident by computerised tomography (CT) and radiography in companion studies as a response to training, in bone in the palmar and dorsal regions of the condyles of the third metacarpal bone (Mc3) of 2-year-old Thoroughbred horses.METHODS: Compositional back-scattered electron (BSE) imaging in scanning electron microscopy (SEM) and confocal scanning laser microscopy

A Boyde; EC Firth

2005-01-01

28

CYTOCHEMISTRY AND ELECTRON MICROSCOPY  

PubMed Central

The aldehydes introduced in this paper and the more appropriate concentrations for their general use as fixatives are: 4 to 6.5 per cent glutaraldehyde, 4 per cent glyoxal, 12.5 per cent hydroxyadipaldehyde, 10 per cent crotonaldehyde, 5 per cent pyruvic aldehyde, 10 per cent acetaldehyde, and 5 per cent methacrolein. These were prepared as cacodylate- or phosphate-buffered solutions (0.1 to 0.2 M, pH 6.5 to 7.6) that, with the exception of glutaraldehyde, contained sucrose (0.22 to 0.55 M). After fixation of from 0.5 hour to 24 hours, the blocks were stored in cold (4°C) buffer (0.1 M) plus sucrose (0.22 M). This material was used for enzyme histochemistry, for electron microscopy (both with and without a second fixation with 1 or 2 per cent osmium tetroxide) after Epon embedding, and for the combination of the two techniques. After fixation in aldehyde, membranous differentiations of the cell were not apparent and the nuclear structure differed from that commonly observed with osmium tetroxide. A postfixation in osmium tetroxide, even after long periods of storage, developed an image that—notable in the case of glutaraldehyde—was largely indistinguishable from that of tissues fixed under optimal conditions with osmium tetroxide alone. Aliesterase, acetylcholinesterase, alkaline phosphatase, acid phosphatase, 5-nucleotidase, adenosine triphosphatase, and DPNH and TPNH diaphorase activities were demonstrable histochemically after most of the fixatives. Cytochrome oxidase, succinic dehydrogenase, and glucose-6-phosphatase were retained after hydroxyaldipaldehyde and, to a lesser extent, after glyoxal fixation. The final product of the activity of several of the above-mentioned enzymes was localized in relation to the fine structure. For this purpose the double fixation procedure was used, selecting in each case the appropriate aldehyde.

Sabatini, David D.; Bensch, Klaus; Barrnett, Russell J.

1963-01-01

29

Scanning Electron Microscopy.  

ERIC Educational Resources Information Center

|Describes the scanning electron microscope, including detection signals (secondary, backscattered, and absorbed electrons and x-rays) sample handling, and applications in various science areas. (SK)|

Smith, Judith A.

1982-01-01

30

Nanometer-scale, quantitative composition mappings of InGaN layers from a combination of scanning transmission electron microscopy and energy dispersive x-ray spectroscopy.  

PubMed

Using elastic scattering theory we show that a small set of energy dispersive x-ray spectroscopy (EDX) measurements is sufficient to experimentally evaluate the scattering function of electrons in high-angle annular dark field scanning transmission microscopy (HAADF-STEM). We then demonstrate how to use this function to transform qualitative HAADF-STEM images of InGaN layers into precise, quantitative chemical maps of the indium composition. The maps obtained in this way combine the resolution of HAADF-STEM and the chemical precision of EDX. We illustrate the potential of such chemical maps by using them to investigate nanometer-scale fluctuations in the indium composition and their impact on the growth of epitaxial InGaN layers. PMID:23089619

Pantzas, K; Patriarche, G; Troadec, D; Gautier, S; Moudakir, T; Suresh, S; Largeau, L; Mauguin, O; Voss, P L; Ougazzaden, A

2012-10-22

31

Electron microscopy of atmospheric particles  

NASA Astrophysics Data System (ADS)

Electron microscopy coupled with energy dispersive spectrometry (EM/EDS) is a powerful tool for single particle analysis. However, the accuracy with which atmospheric particle compositions can be quantitatively determined by EDS is often hampered by substrate-particle interactions, volatilization losses in the low pressure microscope chamber, electron beam irradiation and use of inaccurate quantitation factors. A pseudo-analytical solution was derived to calculate the temperature rise due to the dissipation of the electron energy on a particle-substrate system. Evaporative mass loss for a spherical cap-shaped sulfuric acid particle resting on a thin film supported by a TEM grid during electron beam impingement has been studied. Measured volatilization rates were found to be in very good agreement with theoretical predictions. The method proposed can also be used to estimate the vapor pressure of a species by measuring the decay of X-ray intensities. Several types of substrates were studied. We found that silver-coated silicon monoxide substrates give carbon detection limits comparable to commercially available substrates. An advantage of these substrates is that the high thermal conductivity of the silver reduces heating due to electron beam impingement. In addition, exposure of sulfuric acid samples to ammonia overnight substantially reduces sulfur loss in the electron beam. Use of size-dependent k-factors determined from particles of known compositions shows promise for improving the accuracy of atmospheric particle compositions measured by EM/EDS. Knowledge accumulated during the course of this thesis has been used to analyze atmospheric particles (Minneapolis, MN) selected by the TDMA and collected by an aerodynamic focusing impactor. 'Less' hygroscopic particles, which do not grow to any measurable extent when humidified to ~90% relative humidity, included chain agglomerates, spheres, flakes, and irregular shapes. Carbon was the predominant element detected in these particles. The 'more' hygroscopic particles appear to be liquid spheres and contained sulfur, oxygen, and sometimes cations such as sodium and potassium. In addition, carbon was sometimes found in the more hygroscopic particles.

Huang, Po-Fu

32

Resistivity of thin gold films on mica induced by electron-surface scattering: Application of quantitative scanning tunneling microscopy  

NASA Astrophysics Data System (ADS)

We report a comparison between the resistivity measured on thin gold films deposited on mica, with predictions based upon classical theories of size effects (Drude's, Sondheimer's and Calecki's), as well as predictions based upon quantum theories of electron-surface scattering (the modified theory of Sheng, Xing and Wang, the theory of Tesanovic, Jaric and Maekawa, and that of Trivedi and Aschroft). From topographic images of the surface recorded with a Scanning Tunneling Microscope, we determined the rms roughness amplitude, ? and the lateral correlation length, ? corresponding to a Gaussian representation of the average height-height autocorrelation function, describing the roughness of each sample in the scale of length set by the Fermi wave length. Using (?, ?) as input data, we present a rigorous comparison between resistivity data and predictions based upon the theory of Calecki as well as quantum theoretical predictions without adjustable parameters. The resistivity was measured on gold films of different thickness evaporated onto mica substrates, between 4 K and 300 K. The resistivity data covers the range 0.1 < x(T) < 6.8, for 4 K < T < 300 K, where x(T) is the ratio between film thickness and electron mean free path in the bulk at temperature T. We experimentally identify electron-surface and electron-phonon scattering as the microscopic electron scattering mechanisms giving rise to the macroscopic resistivity. The different theories are all capable of estimating the thin film resistivity to an accuracy better than 10%; however the mean free path and the resistivity characterizing the bulk turn out to depend on film thickness. Surprisingly, only the Sondheimer theory and its quantum version, the modified theory of Sheng, Xing and Wang, predict and increase in resistivity induced by size effects that seems consistent with published galvanomagnetic phenomena also arising from electron-surface scattering measured at low temperatures.

Robles, Marcelo E.; Gonzalez-Fuentes, Claudio A.; Henriquez, Ricardo; Kremer, German; Moraga, Luis; Oyarzun, Simón; Suarez, Marco Antonio; Flores, Marcos; Munoz, Raul C.

2012-02-01

33

Electronic Blending in Virtual Microscopy  

ERIC Educational Resources Information Center

Virtual microscopy (VM) is a relatively new technology that transforms the computer into a microscope. In essence, VM allows for the scanning and transfer of glass slides from light microscopy technology to the digital environment of the computer. This transition is also a function of the change from print knowledge to electronic knowledge, or as…

Maybury, Terrence S.; Farah, Camile S.

2010-01-01

34

Electron Microscopy of Intracellular Protozoa.  

National Technical Information Service (NTIS)

During this fiscal year the morphological effects are studied of an anti-trypanosomal drug, WR 163577 on Trypanosoma rhodesiense by electron microscopy. Exposure of trypomastigotes to a low concentration of the drug resulted only in condensation of kineto...

M. Aikawa

1983-01-01

35

Hormonal regulation of capillary fenestrae in the rat adrenal cortex: quantitative studies using objective lens staging scanning electron microscopy.  

PubMed

High magnification studies of the fenestrated capillary endothelium in the zona fasciculata (ZF) of rat adrenal glands were performed using the objective lens stage of an analytical scanning electron microscope (SEM) equipped with a lanthanum hexaboride emitter (LaB6). Resolution of surface substructure of the luminal membrane obtained with specimens decorated with gold/palladium (Au/Pd) was compared with that observed in others sputter coated with tantalum (Ta). High magnification (50,000x) of the fenestrated endothelium demonstrates that tantalum coating of the cryofractured adrenals improves the substructural detail compared to that seen in Au/Pd decorated specimens. The procedures used in specimen preparation, metal deposition and secondary electron imaging (SEI) are described. Quality imaging achieved using the objective lens stage is a result of the elimination of the SE-III component derived from backscattered electrons. Rat adrenals exhibited uniformly patent capillaries. High magnification micrographs of capillary walls were randomly recorded in two morphometric studies of the fenestral content of capillaries in the rat adrenal cortex. Adrenocorticotropic hormone (ACTH), when administered to rats following dexamethasone (DEX) treatment, significantly reduced the fenestrae/micron 2 of endothelial surface and increased the mean size of fenestrae. After hypophysectomy, the number of fenestrae/micron 2 declined over 48 h; within 2 h after ACTH was given to rats hypophysectomized 48 hours earlier, the fenestrae/micron 2 had increased two-fold. These studies indicate that ACTH plays an important role in modulating fenestral content of the capillary endothelium in the adrenal cortex. PMID:3027881

Apkarian, R P; Curtis, J C

1986-01-01

36

Remineralization of enamel subsurface lesions with casein phosphopeptide-amorphous calcium phosphate: A quantitative energy dispersive X-ray analysis using scanning electron microscopy: An in vitro study  

PubMed Central

Aim: The objective of this study was to quantitatively evaluate the remineralization potential of casein phosphopeptide-amor-phous calcium phosphate paste on enamel subsurface lesions using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX). Materials and Methods: Ninety enamel specimens were prepared from extracted human molars. All specimens were evaluated for mineral content (% weight) using SEM-EDX. The specimens were placed in demineralizing solution for four days to produce artificial carious lesions. The mineral content (calcium/phosphorus ratios, Ca/P ratios) was remeasured using SEM-EDX. The specimens were then randomly assigned to five study groups and one control group of 15 specimens per group. Except for the control group, all group specimens were incubated in remineralizing paste (CPP-ACP paste) for 7, 14, 21, 28, and 35 days twice daily for three minutes. The control group received no treatment with remineralizing paste. All the 90 specimens were stored in artificial saliva at 37°C. After remineralization, the mineral content (% weight) of the samples was measured using SEM-EDX. Results: All the study groups showed very highly significant differences between Ca/P ratios of the demineralized and remineralized samples. There was no significant difference seen in the control group. Conclusion: CPP-ACP paste could significantly remineralize the artificial enamel subsurface lesions in vitro: the remineralizing rates increasing with the time for which the samples were kept in the remineralizing paste. Energy dispersive X-ray analysis is an efficient way to quantitatively assess the changes in mineral content during demineralization and in vitro remineralization processes.

Hegde, Mithra N; Moany, Anu

2012-01-01

37

Self-referenced quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

Self-referenced quantitative phase microscopy (SrQPM) is reported, wherein quantitative phase imaging is achieved through the interference of the sample wave with a reflected version of itself. The off-axis interference between the two beams generates a spatially modulated hologram that is analyzed to quantify the sample's amplitude and phase profile. SrQPM requires approximately one-half of the object field of view to be empty and optically flat, which serves as a reference for the other half of the field of view containing the sample.

Hillman, Timothy R.; Lue, Niyom; Sung, Yongjin; Dasari, Ramachandra R.; So, Peter T. C.; Yaqoob, Zahid

2012-02-01

38

Electron microscopy of ceramic superconductors  

SciTech Connect

The critical current Jc is at least as important as Tc (transition temperature) for applications in superconducting materials. Jc is strongly dependent on microstructure and, in consequence, electron microscopy will continue to be important in the development of practical ceramic superconductors. We will review the progress that has been made over the past year or so in studying the superconductors by electron microscopy techniques of all kinds--conventional, high resolution, analytical, etc. A thorough review is impossible but a bibliography is available, as well as two special issues of Journals. 25 refs., 9 figs.

Mitchell, T.E.; Roy, T.

1988-01-01

39

Quantitative imaging of bilirubin by photoacoustic microscopy  

NASA Astrophysics Data System (ADS)

Noninvasive detection of both bilirubin concentration and its distribution is important for disease diagnosis. Here we implemented photoacoustic microscopy (PAM) to detect bilirubin distribution. We first demonstrate that our PAM system can measure the absorption spectra of bilirubin and blood. We also image bilirubin distributions in tissuemimicking samples, both without and with blood mixed. Our results show that PAM has the potential to quantitatively image bilirubin in vivo for clinical applications.

Zhou, Yong; Zhang, Chi; Yao, Da-Kang; Wang, Lihong V.

2013-03-01

40

Hot electron spectroscopy and microscopy  

NASA Astrophysics Data System (ADS)

Semiconductor heterostructures, such as double-barrier resonant tunnelling diodes and superlattices, are nowadays used for many applications. One very versatile and powerful method to study electronic transport in heterostructures is hot electron spectroscopy. Hot electron spectroscopy can be carried out in two complementary versions: device-based techniques usually employ so-called hot electron transistors (HETs), while ballistic electron emission microscopy (BEEM) uses a scanning tunnelling microscope (STM) as the source of ballistic electrons. In this review, spectroscopic results obtained by these two methods are compared and discussed. It is shown that BEEM results are strongly influenced by electron refraction effects, while the behaviour of HET devices is dominated by inelastic scattering effects in the base and drift region of the device. Thus, STM-based BEEM/S and HET-based spectroscopy are genuinely complementary methods, which yield supplementary results.

Smoliner, J.; Rakoczy, D.; Kast, M.

2004-10-01

41

Electron Microscopy of Intracellular Protozoa.  

National Technical Information Service (NTIS)

We studied the interactions between macrophage-like cells (P388D) and Leishmania braziliensis in vitro under various conditions by light and electron microscopy. When P388D and L. braziliensis were incubated together for two minutes, 90% of the promastigo...

M. Aikawa

1982-01-01

42

Bridging fluorescence microscopy and electron microscopy  

Microsoft Academic Search

Development of new fluorescent probes and fluorescence microscopes has led to new ways to study cell biology. With the emergence\\u000a of specialized microscopy units at most universities and research centers, the use of these techniques is well within reach\\u000a for a broad research community. A major breakthrough in fluorescence microscopy in biology is the ability to follow specific\\u000a targets on

Ben N. G. Giepmans

2008-01-01

43

Quantitative fluorescence microscopy and image deconvolution.  

PubMed

Quantitative imaging and image deconvolution have become standard techniques for the modern cell biologist because they can form the basis of an increasing number of assays for molecular function in a cellular context. There are two major types of deconvolution approaches--deblurring and restoration algorithms. Deblurring algorithms remove blur but treat a series of optical sections as individual two-dimensional entities and therefore sometimes mishandle blurred light. Restoration algorithms determine an object that, when convolved with the point-spread function of the microscope, could produce the image data. The advantages and disadvantages of these methods are discussed in this chapter. Image deconvolution in fluorescence microscopy has usually been applied to high-resolution imaging to improve contrast and thus detect small, dim objects that might otherwise be obscured. Their proper use demands some consideration of the imaging hardware, the acquisition process, fundamental aspects of photon detection, and image processing. This can prove daunting for some cell biologists, but the power of these techniques has been proven many times in the works cited in the chapter and elsewhere. Their usage is now well defined, so they can be incorporated into the capabilities of most laboratories. A major application of fluorescence microscopy is the quantitative measurement of the localization, dynamics, and interactions of cellular factors. The introduction of green fluorescent protein and its spectral variants has led to a significant increase in the use of fluorescence microscopy as a quantitative assay system. For quantitative imaging assays, it is critical to consider the nature of the image-acquisition system and to validate its response to known standards. Any image-processing algorithms used before quantitative analysis should preserve the relative signal levels in different parts of the image. A very common image-processing algorithm, image deconvolution, is used to remove blurred signal from an image. There are two major types of deconvolution approaches, deblurring and restoration algorithms. Deblurring algorithms remove blur, but treat a series of optical sections as individual two-dimensional entities, and therefore sometimes mishandle blurred light. Restoration algorithms determine an object that, when convolved with the point-spread function of the microscope, could produce the image data. The advantages and disadvantages of these methods are discussed. PMID:23931516

Swedlow, Jason R

2013-01-01

44

Connecting ?-fluidics to electron microscopy.  

PubMed

A versatile methodology for electron microscopy (EM) grid preparation enabling total content sample analysis is presented. A microfluidic-dialysis conditioning module to desalt or mix samples with negative stain solution is used, combined with a robotic writing table to micro-pattern the EM grids. The method allows heterogeneous samples of minute volumes to be processed at physiological pH for structure and mass analysis, and allows the preparation characteristics to be finely tuned. PMID:22094535

Kemmerling, Simon; Ziegler, Jörg; Schweighauser, Gabriel; Arnold, Stefan A; Giss, Dominic; Müller, Shirley A; Ringler, Philippe; Goldie, Kenneth N; Goedecke, Nils; Hierlemann, Andreas; Stahlberg, Henning; Engel, Andreas; Braun, Thomas

2011-11-09

45

Spectroscopic imaging in electron microscopy  

SciTech Connect

In the scanning transmission electron microscope, multiple signals can be simultaneously collected, including the transmitted and scattered electron signals (bright field and annular dark field or Z-contrast images), along with spectroscopic signals such as inelastically scattered electrons and emitted photons. In the last few years, the successful development of aberration correctors for the electron microscope has transformed the field of electron microscopy, opening up new possibilities for correlating structure to functionality. Aberration correction not only allows for enhanced structural resolution with incident probes into the sub-angstrom range, but can also provide greater probe currents to facilitate mapping of intrinsically weak spectroscopic signals at the nanoscale or even the atomic level. In this issue of MRS Bulletin, we illustrate the power of the new generation of electron microscopes with a combination of imaging and spectroscopy. We show the mapping of elemental distributions at atomic resolution and also the mapping of electronic and optical properties at unprecedented spatial resolution, with applications ranging from graphene to plasmonic nanostructures, and oxide interfaces to biology.

Pennycook, Stephen J [ORNL; Colliex, C. [Universite Paris Sud, Orsay, France

2012-01-01

46

Cryo-electron microscopy of viruses  

Microsoft Academic Search

Thin vitrified layers of unfixed, unstained and unsupported virus suspensions can be prepared for observation by cryo-electron microscopy in easily controlled conditions. The viral particles appear free from the kind of damage caused by dehydration, freezing or adsorption to a support that is encountered in preparing biological samples for conventional electron microscopy. Cryo-electron microscopy of vitrified specimens offers possibilities for

Marc Adrian; Jacques Dubochet; Jean Lepault; Alasdair W. McDowall

1984-01-01

47

Prototype cantilevers for quantitative lateral force microscopy  

SciTech Connect

Prototype cantilevers are presented that enable quantitative surface force measurements using contact-mode atomic force microscopy (AFM). The ''hammerhead'' cantilevers facilitate precise optical lever system calibrations for cantilever flexure and torsion, enabling quantifiable adhesion measurements and friction measurements by lateral force microscopy (LFM). Critically, a single hammerhead cantilever of known flexural stiffness and probe length dimension can be used to perform both a system calibration as well as surface force measurements in situ, which greatly increases force measurement precision and accuracy. During LFM calibration mode, a hammerhead cantilever allows an optical lever ''torque sensitivity'' to be generated for the quantification of LFM friction forces. Precise calibrations were performed on two different AFM instruments, in which torque sensitivity values were specified with sub-percent relative uncertainty. To examine the potential for accurate lateral force measurements using the prototype cantilevers, finite element analysis predicted measurement errors of a few percent or less, which could be reduced via refinement of calibration methodology or cantilever design. The cantilevers are compatible with commercial AFM instrumentation and can be used for other AFM techniques such as contact imaging and dynamic mode measurements.

Reitsma, Mark G.; Gates, Richard S.; Friedman, Lawrence H.; Cook, Robert F. [Nanomechanical Properties Group, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2011-09-15

48

Epoxy Resins in Electron Microscopy  

PubMed Central

A method of embedding biological specimens in araldite 502 (Ciba) has been developed for materials available in the United States. Araldite-embedded tissues are suitable for electron microscopy, but the cutting qualities of the resin necessitates more than routine attention during microtomy. The rather high viscosity of araldite 502 also seems to be an unnecessary handicap. The less viscous epoxy epon 812 (Shell) produces specimens with improved cutting qualities, and has several features—low shrinkage and absence of specimen damage during cure, minimal compression of sections, relative absence of electron beam-induced section damage, etc.—which recommends it as a routine embedding material. The hardness of the cured resin can be easily adjusted by several methods to suit the materials embedded in it. Several problems and advantages of working with sections of epoxy resins are also discussed.

Finck, Henry

1960-01-01

49

Quantitative metallography of ?-Sn dendrites in Sn3.8Ag0.7Cu ball grid array solder balls via electron backscatter diffraction and polarized light microscopy  

Microsoft Academic Search

Electron backscatter diffraction and polarized light microscopy have been used to quantify the number of crystallographically\\u000a independent ?-Sn dendrites present in near-eutectic, ball grid array Sn-Ag-Cu (SAC) solder balls as a function of cooling\\u000a rate (0.35–3.0C\\/s). Based on these data, it is estimated that a single 900-m-diameter solder ball contains on average eight\\u000a individual ?-Sn dendrites, independent of cooling rate.

A. LaLonde; D. Emelander; J. Jeannette; C. Larson; W. Rietz; D. Swenson; D. W. Henderson

2004-01-01

50

Development and Applications of Quantitative X - Microscopy with Chemical Sensitivity  

NASA Astrophysics Data System (ADS)

X-ray microscopy has been developed to image biological samples with a resolution intermediate between visible light and electron microscopes. Interest in distinguishing different molecules using x-ray microscopy has motivated the effort to combine x-ray microscopy with x-ray absorption near-edge spectroscopy (XANES). This thesis includes three projects. The major part concerns the development and applications of XANES microscopy to quantitatively map DNA and proteins. The two other parts are image formation and image contrast enhancement through deconvolution and the use of carbon-XANES to study soft x-ray irradiation induced chemistry in PMMA (a widely used x-ray resist). For the major part of the thesis, XANES microscopy was applied to examine the content and distribution of DNA and protein in mature sperm cells. Sperm nuclei from five different species of mammals were examined, species chosen for analysis because their sperm contains markedly different proportion of protamine 1 and protamine 2 (which are the basic DNA packing proteins in sperm). This work provides new information about composition and structure of sperm chromatin by showing that the protein to DNA ratio in sperm nuclei is not strongly species dependent.

Zhang, Xiaodong

1995-01-01

51

Thickness Determination of Multilayer Graphene Using Transmission Electron Microscopy  

NASA Astrophysics Data System (ADS)

With dark field transmission electron microscopy and select area electron diffraction (SAED) crystallographic grain boundaries in graphene can be easily imaged. We present a complete, quantitative theoretical model of the SAED pattern that allows determination of the number of layers. Grain boundary maps of single and multilayer graphene grown by chemical vapor deposition will be shown.

Shevitski, Brian; Mecklenburg, Matthew; Wassei, Jonathan; Kaner, Richard; Weiller, Bruce; White, E. R.; Dawson, Ben; Ishigami, Masa; Regan, B. C.

2012-02-01

52

Ballistic Electron Emission Microscopy Study of Novel Quantum Objects and Electronic Defects.  

National Technical Information Service (NTIS)

Over the approximately 2 1/2 year period of the above AFOSR grant, substantial progress has been made in the further development of Ballistic Electron Emission Microscopy (BEEM) as a quantitative microscopic and spectroscopic tool for the characterization...

V. Narayanamurti J. Bowers

2000-01-01

53

Quantitative Phase Imaging in Scanning Optical Microscopy.  

NASA Astrophysics Data System (ADS)

The use of scanning optical microscopy for the purpose of quantitative phase imaging is theoretically and experimentally explored. In particular, several novel system configurations are presented and analyzed for their phase imaging capabilities. In these systems, absorptive filters are placed in the pupils of the microscope to encode object phase slope information into the image signal. With suitable processing and integration, the object phase profile is reconstructed. The phase imaging properties of the scanning optical microscopes are analyzed using a phase wedge model based on scalar diffraction theory. It is shown that the novel two-filter arrangement introduced in this thesis provides an unambiguous response to object phase slope. This permits a quantitative reconstruction of the object phase profile. In addition, the phase measurement is not affected by reflectance or transmittance variations in the object. Both confocal and conventional scanning microscopes are analyzed as a function of the pupil filter. Continuous absorptive filters and split-pupil filters are considered. It is shown that the absorptive pupil filter images twice the range of slopes of the split-pupil systems. In addition, the square root absorptive filter is shown to produce the most linear response for both the confocal and conventional scanning systems. The design, construction and operation of a reflection surface profiling instrument incorporating these phase imaging techniques are described. Measurements are performed with this instrument that confirm the validity of the phase wedge models used to analyze these systems. In addition, surface profile measurements of several samples are presented which demonstrate the operation of this instrument. Important advantages of these systems include the large range of slopes measured and the superior imaging properties of the confocal microscope. Furthermore, there is no restriction on the total extent of the phase variations present in the object. As long as the phase slope remains within the limit determined by the numerical aperture of the objective, the object phase profile can be accurately determined. Finally, these systems are able to image twice the range of slopes of previously reported coherent optical processing systems.

Kulawiec, Andrew William

54

Quantitative electrostatic force microscopy-phase measurements  

Microsoft Academic Search

The phase mode of electrostatic force microscopy (EFM-phase) is a scanning probe microscopy (SPM) technique used to measure electrostatic force gradient. EFM-phase has a higher resolution than scanning Kelvin probe microscopy (SKPM or SKM), but unlike SKPM it does not yield a direct measurement of local potential. Analytical calculations of tip–surface capacitances and their gradients are presented, and the origin

C H Lei; A Das; M Elliott; J E Macdonald

2004-01-01

55

Thermal diffuse scattering in transmission electron microscopy.  

PubMed

In conventional transmission electron microscopy, thermal scattering significantly affects the image contrast. It has been suggested that not accounting for this correctly is the main cause of the Stobbs factor, the ubiquitous, large contrast mismatch found between theory and experiment. In the case where a hard aperture is applied, we show that previous conclusions drawn from work using bright field scanning transmission electron microscopy and invoking the principle of reciprocity are reliable in the presence of thermal scattering. In the aperture-free case it has been suggested that even the most sophisticated mathematical models for thermal diffuse scattering lack in their numerical implementation, specifically that there may be issues in sampling, including that of the contrast transfer function of the objective lens. We show that these concerns can be satisfactorily overcome with modest computing resources; thermal scattering can be modelled accurately enough for the purpose of making quantitative comparison between simulation and experiment. Spatial incoherence of the source is also investigated. Neglect or inadequate handling of thermal scattering in simulation can have an appreciable effect on the predicted contrast and can be a significant contribution to the Stobbs factor problem. PMID:22088442

Forbes, B D; D'Alfonso, A J; Findlay, S D; Van Dyck, D; Lebeau, J M; Stemmer, S; Allen, L J

2011-10-01

56

Electron Microscopy of Tungsten Disulphide Inorganic Nanomaterials.  

National Technical Information Service (NTIS)

Transmission and scanning electron microscopy studies of tungsten disulphide nanomaterials revealed nanotubes and onion-like structures. An electron diffraction pattern confirmed the lattice image of this nanotube. The tungsten disulphide nanomaterials ex...

E. Jelis S. Kerwien T. Chatterjee

2009-01-01

57

National Center for Electron Microscopy Users' Guide.  

National Technical Information Service (NTIS)

The National Center for Electron Microscopy (NCEM) in the Materials and Molecular Research Division of the Lawrence Berkeley Laboratory is a high voltage electron microscope facility for ultra-high resolution or dynamic in-situ studies. This guide describ...

1987-01-01

58

Biochemical Electron Microscopy: Promise and Limitations.  

National Technical Information Service (NTIS)

The paper discusses two approaches to biochemical electron microscopy: (1) isolation and purification of electron microscopically monitored subcellular fractions and (2) determination of subcellular constituents in situ. Three currently available ways of ...

L. A. Sternberger L. Weiss F. Coulston W. A. Thomas

1967-01-01

59

Electron microscopy of specimens in liquid  

Microsoft Academic Search

Imaging samples in liquids with electron microscopy can provide unique insights into biological systems, such as cells containing labelled proteins, and into processes of importance in materials science, such as nanoparticle synthesis and electrochemical deposition. Here we review recent progress in the use of electron microscopy in liquids and its applications. We examine the experimental challenges involved and the resolution

Niels de Jonge; Frances M. Ross

2011-01-01

60

Analytical transmission electron microscopy in materials science  

SciTech Connect

Microcharacterization of materials on a scale of less than 10 nm has been afforded by recent advances in analytical transmission electron microscopy. The factors limiting accurate analysis at the limit of spatial resolution for the case of a combination of scanning transmission electron microscopy and energy dispersive x-ray spectroscopy are examined in this paper.

Fraser, H.L.

1980-01-01

61

Atomic resolution 3D electron diffraction microscopy  

SciTech Connect

Electron lens aberration is the major barrier limiting the resolution of electron microscopy. Here we describe a novel form of electron microscopy to overcome electron lens aberration. By combining coherent electron diffraction with the oversampling phasing method, we show that the 3D structure of a 2 x 2 x 2 unit cell nano-crystal (framework of LTA [Al12Si12O48]8) can be ab initio determined at the resolution of 1 Angstrom from a series of simulated noisy diffraction pattern projections with rotation angles ranging from -70 degrees to +70 degrees in 5 degrees increments along a single rotation axis. This form of microscopy (which we call 3D electron diffraction microscopy) does not require any reference waves, and can image the 3D structure of nanocrystals, as well as non-crystalline biological and materials science samples, with the resolution limited only by the quality of sample diffraction.

Miao, Jianwei; Ohsuna, Tetsu; Terasaki, Osamu; O'Keefe, Michael A.

2002-03-01

62

Four-dimensional ultrafast electron microscopy  

NASA Astrophysics Data System (ADS)

Electron microscopy is arguably the most powerful tool for spatial imaging of structures. As such, 2D and 3D microscopies provide static structures with subnanometer and increasingly with ångstrom-scale spatial resolution. Here we report the development of 4D ultrafast electron microscopy, whose capability imparts another dimension to imaging in general and to dynamics in particular. We demonstrate its versatility by recording images and diffraction patterns of crystalline and amorphous materials and images of biological cells. The electron packets, which were generated with femtosecond laser pulses, have a de Broglie wavelength of 0.0335 Å at 120 keV and have as low as one electron per pulse. With such few particles, doses of few electrons per square ångstrom, and ultrafast temporal duration, the long sought after but hitherto unrealized quest for ultrafast electron microscopy has been realized. Ultrafast electron microscopy should have an impact on all areas of microscopy, including biological imaging. femtoscience | structural dynamics | ultrafast electron crystallography | ultrafast electron diffraction

Lobastov, Vladimir A.; Srinivasan, Ramesh; Zewail, Ahmed H.

2005-05-01

63

Electron Microscopy of Living Insects.  

National Technical Information Service (NTIS)

Electron micrographs of living specimens of the various developmental stages of the insect Tribolium confusum were obtained with a scanning electron microscope. In most cases the specimens resumed their normal activity after being examined with the electr...

R. F. W. Pease T. L. Hayes A. S. Camp N. M. Amer

1966-01-01

64

Quantitative analysis of pyrolytic carbon films by polarized light microscopy  

Microsoft Academic Search

The optical properties of differently textured pyrolytic carbon films were quantitatively analyzed by polarized light microscopy. The light intensity for the investigation of optically anisotropic and birefringent materials by polarized light microscopy was calculated as a function of the analyzer angle and the orientation of the material. From these calculations the dependence of the extinction angle on the optical properties

Andreas Pfrang; Thomas Schimmel

2004-01-01

65

Energy-loss probability in electron microscopy  

SciTech Connect

New general results on the self-energy of fast electrons interacting with metal surfaces are presented with emphasis on the energy-loss problem in electron microscopy. Some applications to both spherical and planar targets are considered. Our results are relevant to the understanding of inelastic electron scattering near small structures, at the nanometer scale.

Echenique, P.M.; Bausells, J.; Rivacoba, A.

1987-02-01

66

Transmission Electron Microscopy: Overview and Challenges  

SciTech Connect

We review recent advances in aberration-corrected scanning transmission electron microscopy that allow sub-Angstrom beams to be used for imaging and spectroscopy, with enormous improvement in sensitivity for single atom detection and the investigation of interfacial electronic structure. Comparison is made between the electronic and structural width of gate oxides, with interpretation through first-principles theory. Future developments are discussed.

Pennycook, Stephen J [ORNL; Lupini, Andrew R [ORNL; Borisevich, Albina Y [ORNL; Varela del Arco, Maria [ORNL; Peng, Yiping [ORNL; Nellist, Peter D. [Nion Company, WA; Duscher, Gerd J M [ORNL; Buczko, R. [University of Kentucky, Lexington; Pantelides, Sokrates T [ORNL

2003-01-01

67

Virtual electron microscopy in cell biology.  

PubMed

Virtual microscopy of histological glass slides can emulate conventional light microscopy. Up till now, such a digital simulation does not exist for ultrathin electron microscopic slides. Because of the relative inaccessibility of electron microscopy, evaluation of subcellular structures by (bio)medical students is performed with the aid of photographic prints. In this article, the generation and evaluation of virtual electron microscopic slides is discussed. A T-lymphoblastic cell was used as an example. Electron microscopic pictures were taken at two magnifications (25,000 and 50,000), processed in an analogue or digital way and stitched to reconstruct the image of the total cell. This image is viewed with a webviewer equipped with pan and zoom functions. The possibility of distinguishing the trilaminar structure of cellular membranes was the requisite. Virtual images obtained at an original magnification of 25,000, scanned at a resolution of 800 ppi could compete with pictures developed directly from negatives obtained by electron microscopy. It is possible to navigate and zoom into details in a way emulating electron microscopy. Virtual electron microscopy is innovative and offers new perspectives to interpret cytological pictures and to teach cell biology in an interactive and unique way. Microsc. Res. Tech., 2010. © 2010 Wiley-Liss, Inc. PMID:20623756

Mione, Sylvia; Bacher, Klaus; Thierens, Hubert; Cornelissen, Maria

2011-03-01

68

Fluorescence-integrated transmission electron microscopy images: integrating fluorescence microscopy with transmission electron microscopy.  

PubMed

This chapter describes high-pressure freezing (HPF) techniques for correlative light and electron microscopy on the same sample. Laser scanning confocal microscopy (LSCM) is exploited for its ability to collect fluorescent, as well as transmitted and back scattered light (BSL) images at the same time. Fluorescent information from a whole mount (preembedding) or from thin sections (post-embedding) can be displayed as a color overlay on transmission electron microscopy (TEM) images. Fluorescence-integrated TEM (F-TEM) images provide a fluorescent perspective to TEM images. The pre-embedding method uses a thin two-part agarose pad to immobilize live Caenorhabditis elegans embryos for LSCM, HPF, and TEM. Pre-embedding F-TEM images display fluorescent information collected from a whole mount of live embryos onto all thin sections collected from that sample. In contrast, the postembedding method uses HPF and freeze substitution with 1% paraformaldehyde in 95% ethanol followed by low-temperature embedding in methacrylate resin. This procedure preserves the structure and function of green fluorescent protein (GFP) as determined by immunogold labeling of GFP, when compared with GFP expression, both demonstrated in the same thin section. PMID:17656756

Sims, Paul A; Hardin, Jeff D

2007-01-01

69

Quantitative phase microscopy with asynchronous digital holography  

Microsoft Academic Search

We demonstrate a new method of measuring quantitative phase in biological materials. The method utilizes asynchronous digital holography, which uses a moving fringe created by acousto-optic modulators. Results are demonstrated on live cell samples. OCIS codes:(090.2880, 110.1650) Holographic interferometry, coherence imaging. Cells are dynamic entities, constantly adjusting their biophysical properties to stay in equilibrium with their environment. An understanding of

Kevin J. Chalut; William J. Brown; Neil Terry

2007-01-01

70

Quantitative strain-field measurement of 1:1 B-site cation ordered domains and antiphase boundaries in Pb(Sc1/2Ta1/2)O3 ceramics by high-resolution transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Quantitative strain measurements of the 1:1 B-site cation ordered domains, antiphase boundaries, and dislocations in a highly ordered Pb(Sc1/2Ta1/2)O3 ceramic have been carried out by high-resolution transmission electron microscopy and geometric phase analysis. A phase shift of ? between two adjacent ordered domains across an antiphase boundary is determined unambiguously. The maximum in-plane strain and lattice rotation induced by a dislocation are 9.5% and 5.4°, respectively. In a defect-free antiphase boundary, the maximum in-plane strain and lattice rotation are 1.8% and 0.9°, respectively. The strain mainly concentrates inside the antiphase boundary.

Tai, Cheuk W.; Lereah, Y.

2009-02-01

71

Electron Microscopy of Oleophobic Monolayers  

Microsoft Academic Search

OLEOPHOBIC monolayers of stearic acid on mica have been studied by means of the electron microscope. Mica was chosen as the substrate because clean surfaces, which are molecularly flat over large areas, are easily obtained by cleavage. Stearic acid was retracted from a solution in hexadecane in the manner described by Bigelow, Pickett and Zisman1 and a preshadowed carbon replica

Robert T. Mathieson

1959-01-01

72

Quantitative microscopy: protein dynamics and membrane organisation.  

PubMed

The mobility of membrane proteins is a critical determinant of their interaction capabilities and protein functions. The heterogeneity of cell membranes imparts different types of motion onto proteins; immobility, random Brownian motion, anomalous sub-diffusion, 'hop' or confined diffusion, or directed flow. Quantifying the motion of proteins therefore enables insights into the lateral organisation of cell membranes, particularly membrane microdomains with high viscosity such as lipid rafts. In this review, we examine the hypotheses and findings of three main techniques for analysing protein dynamics: fluorescence recovery after photobleaching, single particle tracking and fluorescence correlation spectroscopy. These techniques, and the physical models employed in data analysis, have become increasingly sophisticated and provide unprecedented details of the biophysical properties of protein dynamics and membrane domains in cell membranes. Yet despite these advances, there remain significant unknowns in the relationships between cholesterol-dependent lipid microdomains, protein-protein interactions, and the effect of the underlying cytoskeleton. New multi-dimensional microscopy approaches may afford greater temporal and spatial resolution resulting in more accurate quantification of protein and membrane dynamics in live cells. PMID:19416480

Owen, Dylan M; Williamson, David; Rentero, Carles; Gaus, Katharina

2009-04-04

73

Electron microscopy of frozen hydrated eukaryotic flagella.  

PubMed

Resting and active sea urchin sperm flagella have been examined by low-dose electron microscopy of frozen hydrated specimens. The flagella are unfixed, unstained, completely intact, and able to swim vigorously after going through the entire preparative procedure. The most prominent features of the image arise from the edges of the axonemal doublets and central-pair microtubules seen in projection. By comparison with these longitudinal markings, transverse features are less easy to discern, being camouflaged by superposition. However, Fourier transforms of digitized micrographs reveal a remarkable degree of crystalline order in quiescent flagella. Filtered images derived from these Fourier transforms show clearly features arising from the central-pair complex and radial spokes that were obscured in the original data. Potentially complicating effects of specimen thickness are shown to be quantitatively insignificant in the formation of images of unstained frozen hydrated flagella. Determination of native flagellar structure by 3-D reconstruction from multiple-tilted views appears to be feasible. PMID:3611847

Murray, J M

74

Image formation in electron thermoelastic acoustic microscopy  

Microsoft Academic Search

The theory of electron beam acoustic imaging with acoustic wave generation through the thermoelastic effect, or electron thermoelastic acoustic microscopy, has been developed in three dimensions. Images are created through two separate processes: acoustic wave (vibration) generation and acoustic wave transmission. Acoustic wave generation through the thermoelastic effect depends on the material’s thermal and elastic properties. Images based on these

W. L. Holstein

1985-01-01

75

Electron microscopy: Phase transition singled out  

NASA Astrophysics Data System (ADS)

Four-dimensional electron microscopy has been applied to the detailed characterization of metal-organic-framework nanoparticles undergoing an electronic transition. The transition characteristics of a single particle were found to differ from those of an ensemble, and also to vary from one nanoparticle to the next.

Browning, Nigel D.

2013-05-01

76

Quantitative Time-Lapse Fluorescence Microscopy in Single Cells  

PubMed Central

The cloning of GFP 15 years ago revolutionized cell biology by permitting visualization of a wide range of molecular mechanisms within living cells. Though initially used to make largely qualitative assessments of protein levels and localizations, fluorescence microscopy has since evolved to become highly quantitative and high-throughput. Computational image analysis has catalyzed this evolution, enabling rapid and automated processing of large datasets. Here we review studies that combine time-lapse fluorescence microscopy and automated image analysis to investigate dynamic events at the single-cell level. We highlight examples where single-cell analysis provides unique mechanistic insights into cellular processes that cannot be otherwise resolved in bulk assays. Additionally, we discuss studies where quantitative microscopy facilitates the assembly of detailed 4D lineages in developing organisms. Finally, we describe recent advances in imaging technology, focusing especially on platforms that allow the simultaneous perturbation and quantitative monitoring of biological systems.

Muzzey, Dale; van Oudenaarden, Alexander

2011-01-01

77

Ballistic electron microscopy of individual molecules.  

PubMed

We analyzed the transport of ballistic electrons through organic molecules on uniformly flat surfaces of bismuth grown on silicon. For the fullerene C60 and for a planar organic molecule (3,4,9,10-perylene-tetracarboxylic acid dianhydride), the signals revealed characteristic submolecular patterns that indicated where ballistic transport was enhanced or attenuated. The transport was associated to specific electronic molecular states. At electron energies of a few electron volts, this "scanning near-field electron transmission microscopy" method could be applied to various adsorbates or thin layers. PMID:17395824

Bannani, Amin; Bobisch, Christian; Möller, Rolf

2007-03-30

78

Active Pixel Sensors for electron microscopy  

NASA Astrophysics Data System (ADS)

The technology used for monolithic CMOS imagers, popular for cell phone cameras and other photographic applications, has been explored for charged particle tracking by the high-energy physics community for several years. This technology also lends itself to certain imaging detector applications in electron microscopy. We have been developing such detectors for several years at Lawrence Berkeley National Laboratory, and we and others have shown that this technology can offer excellent point-spread function, direct detection and high readout speed. In this paper, we describe some of the design constraints peculiar to electron microscopy and summarize where such detectors could play a useful role.PACS87.64.Ee87.66.PmKeywordsElectron microscopyActive Pixel SensorReferencesC.E. Nelson, et al., 2005, Unpublished results.J.ZuoMicrosc. Res. Tech.492000245D.G.StearnsJ.D.WiedwaldRev. Sci. Instrum.60619891095M.HaiderUltramicroscopy54199441G.Y.FanUltramicroscopy701998107A.R.FaruqiNucl. Instr. and Meth.5132003310G.WecklersIEEE J. Solid-State CircuitsSC-2196765P.NobleIEEE Trans. Electron Dev.ED-151968202(appropriate ref.)Simulation results in this paper are based on the methodology of D. C., Joy, (1995), Monte-Carlo Modeling for Electron Microscopy and Microanalysis, Oxford University Press, with relativistic corrections added by the author.

Denes, P.; Bussat, J.-M.; Lee, Z.; Radmillovic, V.

2007-09-01

79

Quantitative determination of contact stiffness using atomic force acoustic microscopy  

Microsoft Academic Search

Atomic force acoustic microscopy is a near-field technique which combines the ability of ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively, with a resolution of approximately 20nm, exploiting the contact resonance frequencies of standard cantilevers used in

U. Rabe; S. Amelio; E. Kester; V. Scherer; S. Hirsekorn; W. Arnold

2000-01-01

80

Quantitative Phase Microscopy of Live Biological Cell Dynamics  

NASA Astrophysics Data System (ADS)

Interferometric phase microscopy of biological cell dynamics has the potential to provide a label-free quantitative tool for cell biology, as well as for medical diagnosis and monitoring. The current state of the art of this field, the open questions, and specific solutions developed in our laboratory will be presented.

Shaked, Natan T.; Wax, Adam

2010-04-01

81

Embedding method for electron microscopy in biology.  

PubMed

Transmission electron microscopes were commercially available in some foreign countries in the later 1930s. Sectioning for light microscopy was used for electron microscopic observations of the internal structure of cells and tissues in the early days. Paraffin waxes were tested as embedding media, but they were too soft to enable thin sections. Pease and Baker (1948) (74) achieved an early success with the double-embedding method using the plastic "Parlodion" and paraffin wax. PMID:3915837

Kushida, H

1985-12-01

82

Quantitative Chemical Imaging with Multiplex Stimulated Raman Scattering Microscopy  

PubMed Central

Stimulated Raman scattering (SRS) microscopy is a newly developed label-free chemical imaging technique that overcomes the speed limitation of confocal Raman while avoiding the nonresonant-background problem of coherent anti-Stokes Raman scattering (CARS) microscopy. Previous demonstrations were limited to single Raman band measurement. We present a novel modulation multiplexing approach that allows real-time detection of multiple species using the fast Fourier-transform. We demonstrate quantitative determination of chemical concentration of a ternary mixture. Furthermore, two imaging applications are pursued: (1) quantitative determination of oil content, as well as pigment and protein concentration in microalgae cultures; (2) 3D high resolution imaging of blood, lipids, and protein distribution in ex vivo mouse skin tissue. We believe quantitative multiplex SRS uniquely combines the advantage of fast label-free imaging with the fingerprinting capability of Raman spectroscopy and enables numerous applications lipid biology as well as biomedical imaging.

Fu, Dan; Lu, Fa-Ke; Zhang, Xu; Freudiger, Christian; Pernik, Douglas R.; Holtom, Gary; Xie, Xiaoliang Sunney

2012-01-01

83

Improved methods for high resolution electron microscopy  

Microsoft Academic Search

Existing methods of making support films for high resolution transmission electron microscopy are investigated and novel methods are developed. Existing methods of fabricating fenestrated, metal reinforced specimen supports (microgrids) are evaluated for their potential to reduce beam induced movement of monolamellar crystals of C44H90 paraffin supported on thin carbon films. Improved methods of producing hydrophobic carbon films by vacuum evaporation,

J. R. Taylor

1987-01-01

84

Archaeological Ceramics Studied by Scanning Electron Microscopy  

Microsoft Academic Search

The use of scanning electron microscopy combined with energy dispersive X-ray fluorescence analysis in studies of archaeological\\u000a pottery is discussed. The methods are described and results of their application to studies of Precolumbian glossy black pottery\\u000a from northern Peru are reported in some detail.

J. Froh

2004-01-01

85

A quantitative study of the microstructure and crystallographic fiber texture in nickel electrodeposits used in radio-frequency MEMS switches, including a new transmission electron microscopy (TEM) technique for polycrystalline films  

NASA Astrophysics Data System (ADS)

The microstructure of electrodeposited nickel films in radio-frequency (RF) microelectromechanical systems (MEMS) switches has been quantitatively studied to inform and validate multi-scale, multi-physics computer simulations that aim to predict the lifetime and failure mechanisms of the RF MEMS switches. The RF MEMS switches are currently under study at the Purdue University center for the Prediction of Reliability, Integrity, and Survivability of Microsystems (PRISM). An array of microstructural characterization techniques including focused ion beam (FIB) microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy have be used to study the nickel film and to quantify grain size and crystallographic texture and provide information about elemental impurities and surface roughness and impurity elements. Particular emphasis has been placed on quantifying the crystallographic fiber texture of the polycrystalline nickel film as a function of film height within a single specimen using a new transmission electron microscopy (TEM) microtexture method. The TEM method employs a special type of plan view TEM sample and uses hollow cone dark field (HCDF) TEM imaging to spatially map the orientation of individual crystallites at discrete film heights. A trend of increasing 001 fiber texture with film height was discovered, which has implications for the elastic behavior of the MEMS device. The method can be applied to study fiber texture evolution as a function of height in polycrystalline films to gather data that may elucidate fundamental film growth mechanisms. The method is explained in detail. It is well-known that the elastic properties of polycrystalline thin films used in MEMS devices can deviate from bulk isotropic values and become directionally-dependent if a crystallographic texture is present. Hence, the ability to predict the actual anisotropic elastic properties of textured films is important for MEMS design and analysis. An integrated technique combining X-ray diffraction (XRD) and density functional theory (DFT) simulation is presented here for the quantification and prediction of the elastic properties of crystallographically textured polycrystalline films used in MEMS devices. The technique is rapid, efficient, and capable of analyzing individual devices in an array, making it ideal for MEMS design, analysis, and quality control. Application of the technique to the electroplated nickel bridge of an RF MEMS switch, whose critical operating parameters depend on the in-plane Young's modulus, is demonstrated. It is shown that the in-plane Young's modulus of nickel films with a perfect, single fiber texture can vary over a large range from 172 GPa to 232 GPa. Experimental results significantly outside this range cannot be explained by crystallographic texture alone. The range of Young's modulus for real films is expected to be somewhat smaller because real films rarely have a near- perfect fiber texture and sometimes have a texture that cannot be described by a single fiber of orientation. The nickel bridge of the RF MEMS switch, which has a relatively strong 001 fiber texture component as well as a weak 111 fiber texture component, exemplifies such a case. The present technique takes these texture features into account to estimate the in-plane Young's modulus of the nickel bridge in several RF MEMS switches.

Cantwell, Patrick R.

86

Sparse imaging for fast electron microscopy  

NASA Astrophysics Data System (ADS)

Scanning electron microscopes (SEMs) are used in neuroscience and materials science to image centimeters of sample area at nanometer scales. Since imaging rates are in large part SNR-limited, large collections can lead to weeks of around-the-clock imaging time. To increase data collection speed, we propose and demonstrate on an operational SEM a fast method to sparsely sample and reconstruct smooth images. To accurately localize the electron probe position at fast scan rates, we model the dynamics of the scan coils, and use the model to rapidly and accurately visit a randomly selected subset of pixel locations. Images are reconstructed from the undersampled data by compressed sensing inversion using image smoothness as a prior. We report image fidelity as a function of acquisition speed by comparing traditional raster to sparse imaging modes. Our approach is equally applicable to other domains of nanometer microscopy in which the time to position a probe is a limiting factor (e.g., atomic force microscopy), or in which excessive electron doses might otherwise alter the sample being observed (e.g., scanning transmission electron microscopy).

Anderson, Hyrum S.; Ilic-Helms, Jovana; Rohrer, Brandon; Wheeler, Jason; Larson, Kurt

2013-02-01

87

Simulation of Spatially Resolved Electron Energy Loss Near-Edge Structure for Scanning Transmission Electron Microscopy  

NASA Astrophysics Data System (ADS)

Aberration-corrected scanning transmission electron microscopy yields probe-position-dependent energy-loss near-edge structure (ELNES) measurements, potentially providing spatial mapping of the underlying electronic states. ELNES calculations, however, typically describe excitations by a plane wave traveling in vacuum, neglecting the interaction of the electron probe with the local electronic environment as it propagates through the specimen. Here, we report a methodology that combines a full electronic-structure calculation with propagation of a focused beam in a thin film. The results demonstrate that only a detailed calculation using this approach can provide quantitative agreement with observed variations in probe-position-dependent ELNES.

Prange, M. P.; Oxley, M. P.; Varela, M.; Pennycook, S. J.; Pantelides, S. T.

2012-12-01

88

Ballistic electron microscopy of nanographene layers.  

PubMed

We use scanning tunneling microscopy and ballistic electron emission spectroscopy and microscopy to study charge transport across Pt-nanographene-Pd interfaces. Four triangle-shaped nanographene molecules with different bulky substituents are studied. Modifications of highest occupied molecular orbital and lowest unoccupied molecular orbital levels resulting from hybridization with the metal substrate are observed for all molecules and compared with theoretical calculations. The substituents can influence the charge transport through the molecules by varying the distance between the metal substrate and the nanographene plane or providing additional electronic channels through iodo substituents. This effect can be quantified as a larger effective mass for carriers with increasing molecule-substrate distance, using tight binding. Our results address the critical coupling issue for metal contacts to devices using molecules as active layers. PMID:19367800

Feng, Xinliang; Chandrasekhar, Natarajan; Su, Haibin; Müllen, Klaus

2008-12-01

89

Quantitative dynamic footprinting microscopy reveals mechanisms of neutrophil rolling  

PubMed Central

We introduce quantitative dynamic footprinting microscopy to resolve neutrophil rolling on P-selectin. We show that the footprint of a rolling neutrophil is four times larger than previously thought, the P-selectin-PSGL-1 bonds are relaxed at the leading edge of the rolling cell, compressed under the cell center, and stretched at the trailing edge. Each rolling neutrophil also forms 3-4 long tethers that extend up to 16 ?m behind the rolling cell.

Sundd, Prithu; Gutierrez, Edgar; Pospieszalska, Maria K.; Zhang, Hong; Groisman, Alexander; Ley, Klaus

2010-01-01

90

Quantitative Photo Activated Localization Microscopy: Unraveling the Effects of Photoblinking  

PubMed Central

In this work we discuss how to use photophysical information for improved quantitative measurements using Photo Activated Localization Microscopy (PALM) imaging. We introduce a method that reliably estimates the number of photoblinking molecules present in a biological sample and gives a robust way to quantify proteins at the single-cell level from PALM images. We apply this method to determine the amount of ?2 adrenergic receptor, a prototypical G Protein Coupled Receptor, expressed on the plasma membrane of HeLa cells.

Rothlisberger, Ursula; Radenovic, Aleksandra

2011-01-01

91

Transmission electron microscopy of nanomachined silicon crystals  

Microsoft Academic Search

Silicon substrate slices in (111) or (001) surface orientation have been machined in two ways: precision ground by a diamond abrasive wheel to a surface roughness Ra ? 11 nm, or turned on a highly stiff single-point diamond turning machine to Ra,?0·5 nm. Transmission electron microscopy of cross-sections of the machined surfaces has established the following.1. The mean depth of

K. E. Puttick; L. C. Whitmore; C. L. Chao; A. E. Gee

1994-01-01

92

Electron microscopy of sister chromatid exchanges  

Microsoft Academic Search

BrdU-substituted chromosomes of Don cells were differentially stained with ammoniacal silver carbonate and analyzed by electron microscopy. The results obtained led us to the following conclusions: (1) the differential impregnation of BrdU-substituted chromatids with silver is mainly due to a preferential extraction of non-histone proteins caused by UV-irradiation and incubation in SSC at 55 °C prior to silver staining; (2)

V. J. Goyanes; J. B. Schvartzman

1983-01-01

93

Fixation of Ejaculated Spermatozoa for Electron Microscopy  

Microsoft Academic Search

EJACULATED spermatozoa cannot be preserved satisfactorily by conventional fixation procedures for electron microscopy. Osmium tetroxide (OsO4) fixation of crude ejaculate consistently produces a variety of artefacts such as separation of the plasma membrane from the acrosome, widening of nuclear vacuoles, erosion of the acrosome, and swelling of mitochondria1-3. These alterations could be the consequence of the rapid destruction of the

Mario Stefanini; Cesare De Martino; Luciano Zamboni

1967-01-01

94

Analytical transmission electron microscopy in minerals processing  

SciTech Connect

A review of the possibilities of performing microchemical analysis in thin sections using a combination of scanning transmission electron microscopy and energy dispersive spectroscopy of x-rays is given. Particular attention is paid to the factors that limit accurate analysis at the highest spatial resolution. As an example of the use of these techniques applied to a potential problem in minerals processing, the identification of pyrite and pyrrhotite particles in Illinois, Herrin number 6 coal is presented.

Fraser, H.L.; Hsieh, K.C.; Twigg, M.E.

1981-01-01

95

Transmission Electron Microscopy of Minerals and Rocks  

NASA Astrophysics Data System (ADS)

Of the many techniques that have been applied to the study of crystal defects, none has contributed more to our understanding of their nature and influence on the physical and chemical properties of crystalline materials than transmission electron microscopy (TEM). TEM is now used extensively by an increasing number of earth scientists for direct observation of defect microstructures in minerals and rocks. Transmission Electron Microscopy of Rocks and Minerals is an introduction to the principles of the technique and is the only book to date on the subject written specifically for geologists and mineralogists. The first part of the book deals with the essential physics of the transmission electron microscope and presents the basic theoretical background required for the interpretation of images and electron diffraction patterns. The final chapters are concerned with specific applications of TEM in mineralogy and deal with such topics as planar defects, intergrowths, radiation-induced defects, dislocations and deformation-induced microstructures. The examples cover a wide range of rock-forming minerals from crustal rocks to those in the lower mantle, and also take into account the role of defects in important mineralogical and geological processes.

McLaren, Alex C.

1991-04-01

96

A Quantitative Model of Ionospheric Electron Density.  

National Technical Information Service (NTIS)

This report summarizes work performed during the entire contract period. The general goal was to develop a quantitative global ionospheric electron density model that can be used to predict variations in the electron density. The model developed under thi...

W. P. Olson K. A. Pfitzer

1978-01-01

97

Contribution of Electron Microscopy of Materials Science to Society.  

National Technical Information Service (NTIS)

The examples discussed are just a few of very many that could be used to illustrate the impact of electron microscopy in materials upon society. Electron microscopy, materials science and engineering represent classic examples of demanding and interdiscip...

G. Thomas

1987-01-01

98

Scanning electron microscopy of lichen sclerosus*  

PubMed Central

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

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

2013-01-01

99

Microfluidic system for transmission electron microscopy  

SciTech Connect

We present a microfluidic system that maintains liquid flow in a specimen chamber for (scanning) transmission electron microscope ((S)TEM) imaging. The specimen chamber consists of two ultra-thin silicon nitride windows supported by silicon microchips. They are placed in a specimen holder that seals the sample from the vacuum in the electron microscope, and incorporates tubing to and from the sample connected to a syringe pump outside the microscope. Using results obtained from fluorescence microscopy of microspheres flowing through the system, an equation to characterize the liquid flow through the system was calibrated. Gold nanoparticles of diameters of 30 and 100 nm moving in liquid were imaged with a 200 kV STEM. It was concluded that despite strong influences from Brownian motion, and sensitivity to small changes in the depth of the bypass channel, the electron microscopy flow data matched the calculated flow speed within an order of magnitude. The system allows for rapid (within a minute) liquid exchange, which can potentially be used, for example, to investigate the response of specimens, e.g., eukaryotic-, or bacterial cells, to certain stimuli.

Ring, Elisabeth A [ORNL; De Jonge, Niels [ORNL

2010-01-01

100

Electron microscopy through micrometers thick water layers  

SciTech Connect

Scanning transmission electron microscopy can be used to image specimens in water layers of several micrometers thickness, sufficiently thick to contain eukaryotic cells. We determined the resolution obtained on gold nanoparticles above and below water layers with thicknesses ranging from 1.3 13 m. The best achieved resolution values were 1.4 nm and 9 nm, above 3.3 m and below 1.3 m of water, respectively. A theoretical model included probe broadening and Monte Carlo simulations were developed to describe the resolution as function of the sample parameters.

Peckys, Diana B [ORNL; Poirier-Demers, Nicolas [University of Sherbrooke; Drouin, Dominique [University of Sherbrooke; De Jonge, Niels [ORNL

2010-01-01

101

Quantitative phase microscopy and synthetic aperture tomography of live cells  

NASA Astrophysics Data System (ADS)

For more than a decade MIT's George R. Harrison Spectroscopy Laboratory has been developing quantitative phase microscopy (QPM) for biological study. Measurements of a point field were made in the mid 90s, then extended to the full 2D field, and recently, to 3D by using tomography. In the first part of this thesis improvements in the techniques of Fourier Phase Microscopy (FPM) and Hilbert Phase Microscopy (HPM) and their applications to characterize cells and tissues are reported. Tomographic phase microscopy (TPM) provides quantitative information and highly detailed structural information about a live cell, but in its current form it can only examine one cell at a time. Many biological applications including statistical analysis of a large collection of cells such as flow cytometry need a tomography technique that can measure many cells at a time. For the second part of this thesis we have developed a new tomography technique that can measure many cells continuously. In this study we demonstrate the new technique by translating a live cell across a focused beam. This beam is composed of many angular plane waves, and by applying a so-called synthetic aperture algorithm we retrieve individual wave components of the focused beam. We demonstrate for the first time that we can retrieve the field of the focused beam and synthesize any arbitrary angular plane wave. We then construct a 3D map of the variations of the refractive index in a live cell from a series of these synthesized angular plane waves. This new technique is the first step needed to analyze cells flowing through a beam to provide a high-throughput 3D refractive index tomograms that can be used as a new kind of statistical optical assay of living cells.

Lue, Niyom

102

Quantitative single-molecule imaging by confocal laser scanning microscopy  

PubMed Central

A new approach to quantitative single-molecule imaging by confocal laser scanning microscopy (CLSM) is presented. It relies on fluorescence intensity distribution to analyze the molecular occurrence statistics captured by digital imaging and enables direct determination of the number of fluorescent molecules and their diffusion rates without resorting to temporal or spatial autocorrelation analyses. Digital images of fluorescent molecules were recorded by using fast scanning and avalanche photodiode detectors. In this way the signal-to-background ratio was significantly improved, enabling direct quantitative imaging by CLSM. The potential of the proposed approach is demonstrated by using standard solutions of fluorescent dyes, fluorescently labeled DNA molecules, quantum dots, and the Enhanced Green Fluorescent Protein in solution and in live cells. The method was verified by using fluorescence correlation spectroscopy. The relevance for biological applications, in particular, for live cell imaging, is discussed.

Vukojevic, Vladana; Heidkamp, Marcus; Ming, Yu; Johansson, Bjorn; Terenius, Lars; Rigler, Rudolf

2008-01-01

103

Quantitative Phase Contrast Digital Holographic Microscopy in Biophotonics  

NASA Astrophysics Data System (ADS)

Label-free, non-contact, non-destructive, on-line (video repetition rate), high resolution, full field (no scanning), quantitative analysis of morphology and dynamic processes in living cells are required features in life science research and medical diagnostics. Digital Holography combined with microscopic imaging provides these features simultaneously. The modular integration of digital holographic microscopy (DHM) into commercial microscopes yields an axial resolution with interferometric resolution while the lateral resolution is diffraction limited. As amplitude and phase are available by numerical reconstruction from a single digital hologram subsequent automated focus correction is enabled. The evaluation of quantitative digital holographic phase contrast images permits also an effective detection of lateral object movements. Thus, 3D tracking is achieved. The applicability of DHM techniques for dynamic live cell analysis is demonstrated by results from tumor cells and human erythrocytes.

Kemper, Björn; Langehanenberg, Patrik; von Bally, Gert

2010-11-01

104

Nanometric crystal defects in transmission electron microscopy.  

PubMed

Transmission electron microscopy (TEM) is revisited in order to define methods for the identification of nanometric defects. Nanometric crystal defects play an important role as they influence, generally in a detrimental way, physical properties. For instance, radiation-induced damage in metals strongly degrades mechanical properties, rendering the material stronger but brittle. The difficulty in using TEM to identify the nature and size of such defects resides in their small size. TEM image simulations are deployed to explore limits and possible ways to improve on spatial resolution and contrast. The contrast of dislocation loops, cavities, and a stacking fault tetrahedra (SFT) are simulated in weak beam, interfering reflections (HRTEM), and scanned condensed electron probe (STEM) mode. Results indicate that STEM is a possible way to image small defects. In addition, a new objective aperture is proposed to improve resolution in diffraction contrast. It is investigated by simulations of the weak beam imaging of SFT and successfully applied in experimental observations. PMID:16646011

Schäublin, Robin

2006-05-01

105

Trends in low energy electron microscopy.  

PubMed

Low energy electron microscopy (LEEM) and spin polarized LEEM (SPLEEM) are two powerful in situ techniques for the study of surfaces, thin films and other surface-supported nanostructures. Their real-time imaging and complementary diffraction capabilities allow the study of structure, morphology, magnetism and dynamic processes with high spatial and temporal resolution. Progress in methods, instrumentation and understanding of novel contrast mechanisms that derive from the wave nature and spin degree of freedom of the electron continue to advance applications of LEEM and SPLEEM in these areas and beyond. We review here the basic imaging principles and recent developments that demonstrate the current capabilities of these techniques and suggest potential future directions. PMID:21389393

Altman, M S

2010-02-05

106

Electron Microscopy of Botrytis cinerea Conidia  

PubMed Central

Buckley, Patricia M. (University of California, Davis), Virginia E. Sjaholm, and N. F. Sommer. Electron microscopy of Botrytis cinerea conidia. J. Bacteriol. 91:2037–2044. 1966.—Sections of germinating and nongerminating Botrytis cinerea conidia were examined with an electron microscope. Uranyl acetate or lead citrate provided contrast between membranes and cytoplasm. Membrane-bounded, dense inclusions previously unreported in dormant spores were termed “storage bodies.” Whorled structures, spherules, granules, and membrane loops were seen within these inclusions. The various forms assumed by the enclosed materials closely resemble phospholipid inclusions described for other cells. It is suggested that the inclusions provide material for the assembly of membranous organelles during germination. Utilization of the stored material apparently results in extensive vacuolization in advanced germinants. Images

Buckley, Patricia M.; Sjaholm, Virginia E.; Sommer, N. F.

1966-01-01

107

Scanning electron microscopy studies of bacterial cultures  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

108

Integrated Electron Microscopy: Super-Duper Resolution  

PubMed Central

Since its inception, electron microscopy (EM) has revealed that cellular membranes are organized into structurally distinct subdomains, created by localized protein and lipid assemblies to perform specific complex cellular functions. Caveolae are membrane subdomains that function as signaling platforms, endocytic carriers, sensors of membrane tension, and mechanical stress, as well as in lipid homeostasis. They were first discovered almost 60 years ago by pioneering electron microscopists. While new and exciting developments in SUPER-resolution fluorescent light microscopy facilitate studies of the spatial organization of fluorescently labeled protein components, these techniques cannot reveal the underlying cellular structures. Thus, equally exciting are developments in EM: genetically encoded probes for protein localization at sub-10 nm resolution, more powerful instruments that allow imaging of larger cell volumes, and computational methods for reconstructing three-dimensional images. Used in combination, as done by Ludwig et al. in the current issue of PLOS Biology, these tools reveal high-resolution insights into the composition and organization of the caveolae coat and the formation of these specialized structures. Together, these advances are contributing to a resurgence in EM.

Krijnse Locker, Jacomine; Schmid, Sandra L.

2013-01-01

109

High-resolution transmission electron microscopy: the ultimate nanoanalytical technique.  

PubMed

To be able to determine the elemental composition and morphology of individual nanoparticles consisting of no more than a dozen or so atoms that weigh a few zeptograms (10(-21) g) is but one of the attainments of modern electron microscopy. With slightly larger specimens (embracing a few unit cells of the structure) their symmetry, crystallographic phase, unit-cell dimension, chemical composition and often the valence state (from parallel electron spectroscopic measurements) of the constituent atoms may also be determined using a scanning beam of electrons of ca. 0.5 nm diameter. Nowadays electron crystallography, which treats the digital data of electron diffraction (ED) and high-resolution transmission electron microscope (HRTEM) images of minute (ca. 10(-18)g) specimens in a quantitatively rigorous manner, solves hitherto unknown structures just as X-ray diffraction does with bulk single crystals. In addition, electron tomography (see cover photograph and its animation) enables a three-dimensional picture of the internal structure of minute objects, such as nanocatalysts in a single pore, as well as structural faults such as micro-fissures, to be constructed with a resolution of 1 nm from an angular series of two-dimensional (projected) images. Very recently (since this article was first written) a new meaning has been given to electron crystallography as a result of the spatio-temporal resolution of surface phenomena achieved on a femtosecond timescale. PMID:15154029

Thomas, John Meurig; Midgley, Paul A

2004-05-07

110

Quantitative analysis of live cells using digital holographic microscopy  

NASA Astrophysics Data System (ADS)

During the life time of a cell, it goes through changes to the plasma membrane as well as its internal structures especially distinctive during processes like cell division and death. Different types of microscope are used to fulfill the observation of the cell's variation. In our experiment, Vero cells have been investigated by using phase contrast microscopy and digital holographic microscopy (DHM). A comparison of the images obtained for cell division is presented here. The conventional phase contrast microscope provided a good imaging method in the real time analysis of cell division. The off-axis digital hologram recorded by the DHM system can be reconstructed to obtain both the intensity image and phase contrast image of the test object. These can be used for live cell imaging to provide multiple results from a single equipment setup. The DHM system, besides being a qualitative tool, is able to provide quantitative results and 3D images of the cell division process. The ability of DHM to provide quantitative analysis makes it an ideal tool for life science applications.

Lewis, Tan Rongwei; Qu, Weijuan; Chee, Oi Choo; Singh, Vijay Raj; Asundi, Anand

2009-12-01

111

A Quantitative Assessment of Electronic Commerce  

Microsoft Academic Search

This paper tries to assess quantitatively the role of electronic commerce in economic activity and in trade and tariff revenue collection. The share of value added that potentially lends itself to electronic trade represents around 30 percent of GDP, most importantly distribution, finance and business services. Electronic commerce is also likely to boost trade in many services sectors significantly. Despite

L. Schuknecht; R. Perez-Esteve

1999-01-01

112

Chromosome structure: improved immunolabeling for electron microscopy.  

PubMed

To structurally dissect mitotic chromosomes, we aim to position along the folded chromatin fiber proteins involved in long-range order, such as topoisomerase IIalpha (topoIIalpha) and condensin. Immuno-electron microscopy (EM) of thin-sectioned chromosomes is the method of choice toward this goal. A much-improved immunoprocedure that avoids problems associated with aldehyde fixation, such as chemical translinking and networking of chromatin fibers, is reported here. We show that ultraviolet irradiation of isolated nuclei or chromosomes facilitates high-level specific immunostaining, as established by fluorescence microscopy with a variety of antibodies and especially by immuno-EM. Ultrastructural localizations of topoIIalpha and condensin I component hBarren (hBar; hCAP-H) in mitotic chromosomes were studied by immuno-EM. We show that the micrographs of thin-sectioned chromosomes map topoIIalpha and hBar to the center of the chromosomal body where the chromatin fibers generally converge. This localization is defined by many clustered gold particles with only rare individual particles in the peripheral halo. The data obtained are consistent with the view that condensin and perhaps topoIIalpha tether chromatin to loops according to a scaffolding-type model. PMID:16175370

Maeshima, Kazuhiro; Eltsov, Michail; Laemmli, Ulrich K

2005-11-12

113

X-ray and electron microscopy of actinide materials  

Microsoft Academic Search

Actinide materials demonstrate a wide variety of interesting physical properties in both bulk and nanoscale form. To better understand these materials, a broad array of microscopy techniques have been employed, including transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), energy dispersive X-ray spectroscopy (EDXS), high-angle annular dark-field imaging (HAADF), scanning electron microscopy (SEM), wavelength dispersive X-ray spectroscopy (WDXS), electron back

Kevin T. Moore

2010-01-01

114

Scanning electron microscopy of molluscum contagiosum*  

PubMed Central

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

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

2013-01-01

115

Improved methods for high resolution electron microscopy  

SciTech Connect

Existing methods of making support films for high resolution transmission electron microscopy are investigated and novel methods are developed. Existing methods of fabricating fenestrated, metal reinforced specimen supports (microgrids) are evaluated for their potential to reduce beam induced movement of monolamellar crystals of C/sub 44/H/sub 90/ paraffin supported on thin carbon films. Improved methods of producing hydrophobic carbon films by vacuum evaporation, and improved methods of depositing well ordered monolamellar paraffin crystals on carbon films are developed. A novel technique for vacuum evaporation of metals is described which is used to reinforce microgrids. A technique is also developed to bond thin carbon films to microgrids with a polymer bonding agent. Unique biochemical methods are described to accomplish site specific covalent modification of membrane proteins. Protocols are given which covalently convert the carboxy terminus of papain cleaved bacteriorhodopsin to a free thiol. 53 refs., 19 figs., 1 tab.

Taylor, J.R.

1987-04-01

116

Scanning electron microscopy of removed intraocular lenses.  

PubMed

During a six-year period, 27 intraocular lenses (2%) were removed from a population of 1,794 implanted eyes. The frequency of and reasons for removal of the lenses, as well as patient information, dates of insertion and removal, types of surgery, and lens manufacturers, were recorded. Twelve of 15 lenses obtained for study were examined by scanning electron microscopy. These revealed poor finish quality, molding defects, and loop degradation. In the first four years the incidence of lens removal was approximately 3.8%. During the following three years, there was a dramatic reduction in the number of lenses removed, suggesting that increased experience and better lens design led to fewer lens removals. PMID:6874538

Siepser, S B; Kline, O R

1983-01-01

117

Development of Quantitative electron nano-diffraction  

Microsoft Academic Search

This thesis is a step towards development of quantitative parallel beam electron nano-diffraction (PBED). It is focused on the superstructure determination of zig-zag and zig-zig NaxCoO2 and analysis of charge distribution in the two polymorphs Nb12O29 using PBED. It has been shown that quantitative electron nano-diffraction (parallel beam) has the potential of solving superstructures as well as charge distribution by

V. Kumar

2009-01-01

118

Quantitative analysis of cardiomyocyte dynamics with optical coherence phase microscopy  

NASA Astrophysics Data System (ADS)

Spectral domain optical coherence microscopy (OCM) is an interferometric imaging technique for three-dimensional reconstruction of biological samples. Phase sensitive implementation of OCM has generally been in common path interferometer configuration to obtain high phase stability, which limits the numerical aperture of the imaging optics and the transverse resolution. Here, we describe the implementation of optical coherence phase microscope in asymmetric Linnik interferometer configuration, which provides phase stability of 0.5 milliradians along with high spatial resolution. Three-dimensional structural images and dynamic displacement images obtained from spontaneously active cardiomyocytes demonstrate that the phase information could potentially be used for quantitative analysis of contraction dynamics, spatially resolved to sub-cellular structures.

Ansari, Rehman; Aherrahrou, Redouane; Aherrahrou, Zouhair; Erdmann, Jeanette; Hüttmann, Gereon; Schweikard, Achim

2012-02-01

119

Fluorescence microscopy procedure for quantitation of yeasts in beverages.  

PubMed

Existing methods for quantitating yeasts in beverages include time-consuming plate counts that detect only living cells and hemacytometer counts that are reliable only at very high concentrations (e.g., 10(6) to 20 X 10(6) cells per ml). The new method described here involves the use of fluorescence microscopy with the fluorescent stain aniline blue to differentiate yeasts (and other fungi) from backgrounds for easy counting and also may be used in conjunction with membrane filtration to concentrate yeasts from liquids before cell enumeration. Recoveries averaged 91.5% for beverages spiked with levels of 500 to 600,000 organisms per ml. The correlation coefficient of count to spike level was 0.996. PMID:3767366

Koch, H A; Bandler, R; Gibson, R R

1986-09-01

120

Fluorescence microscopy procedure for quantitation of yeasts in beverages.  

PubMed Central

Existing methods for quantitating yeasts in beverages include time-consuming plate counts that detect only living cells and hemacytometer counts that are reliable only at very high concentrations (e.g., 10(6) to 20 X 10(6) cells per ml). The new method described here involves the use of fluorescence microscopy with the fluorescent stain aniline blue to differentiate yeasts (and other fungi) from backgrounds for easy counting and also may be used in conjunction with membrane filtration to concentrate yeasts from liquids before cell enumeration. Recoveries averaged 91.5% for beverages spiked with levels of 500 to 600,000 organisms per ml. The correlation coefficient of count to spike level was 0.996. Images

Koch, H A; Bandler, R; Gibson, R R

1986-01-01

121

Towards a quantitative analysis of magnetic force microscopy data matrices  

NASA Astrophysics Data System (ADS)

Fast and efficient software tools previously developed in image processing were adapted to the analysis of raw datasets consisting of multiple stacks of images taken on a sample interacting with a measuring instrument and submitted to the effect of an external parameter. Magnetic force microscopy (MFM), a follow-up of atomic force microscopy (AFM), was selected as a first testbed example. In MFM, a specifically developed ferromagnetic scanning tip probes the stray magnetic field generated from a ferromagnetic specimen. Raw scanning probe images taken on soft patterned magnetic materials and continuous thin films were used, together with synthetic patterns exploited to assess the absolute performance ability of the proposed texture analysis tools. In this case, the parameter affecting the sample-instrument interaction is the applied magnetic field. The application discussed here is just one among the many possible, including, e.g., real-time microscopy images (both optical and electronic) taken during heat treatments, phase transformations and so on. Basically any image exhibiting a texture with a characteristic spatial or angular dependence could be processed by the proposed method. Standard imaging tools such as texture mapping and novel data representation schemes such as texture analysis, feature extraction and classification are discussed. A magnetic texture stability diagram will be presented as an original output of the entropic analysis on MFM datasets.

Chiolerio, A.; Allia, P.

2012-08-01

122

Quantitative fluorescent speckle microscopy (QFSM) to measure actin dynamics.  

PubMed

Quantitative fluorescent speckle microscopy (QFSM) is a live-cell imaging method to analyze the dynamics of macromolecular assemblies with high spatial and temporal resolution. Its greatest successes were in the analysis of actin filament and adhesion dynamics in the context of cell migration and microtubule dynamics in interphase and the meiotic/mitotic spindle. Here, focus is on the former application to illustrate the procedures of FSM imaging and the computational image processing that extracts quantitative information from these experiments. QFSM is advantageous over other methods because it measures the movement and turnover kinetics of the actin filament (F-actin) network in living cells across the entire field of view. Experiments begin with the microinjection of fluorophore-labeled actin into cells, which generate a low ratio of fluorescently labeled to endogenously unlabeled actin monomers. Spinning disk confocal or wide-field imaging then visualizes fluorophore clusters (two to eight actin monomers) within the assembled F-actin network as speckles. QFSM software identifies and computationally tracks and utilizes the location, appearance, and disappearance of speckles to derive network flows and maps of the rate of filament assembly and disassembly. PMID:23042526

Mendoza, Michelle C; Besson, Sebastien; Danuser, Gaudenz

2012-10-01

123

Quantitative Fluorescent Speckle Microscopy (QFSM) to Measure Actin Dynamics  

PubMed Central

Quantitative Fluorescent Speckle Microscopy (QFSM) is a live cell imaging method to analyze the dynamics of macromolecular assemblies with high spatial and temporal resolution. Its greatest successes were in the analysis of actin filament and adhesion dynamics in the context of cell migration and microtubule dynamics in interphase and the meotic/mitotic spindle. Here, we focus on the former application to illustrate the procedures of FSM imaging and the computational image processing that extracts quantitative information from these experiments. QFSM is advantageous over other methods because it measures the movement and turnover kinetics of the actin filament (F-actin) network in living cells across the entire field of view. Experiments begin with microinjection of fluorophore-labeled actin into cells, which generate a low ratio of fluorescently-labeled:endogenous unlabeled actin monomers. Spinning disk confocal or wide-field imaging then visualizes fluorophore clusters (2–8 actin monomers) within the assembled F-actin network as speckles. QFSM software identifies and computationally tracks and utilizes the location, appearance, and disappearance of speckles to derive network flows and maps of the rate of filament assembly and disassembly.

Mendoza, Michelle C.; Besson, Sebastien; Danuser, Gaudenz

2012-01-01

124

Photon-induced near-field electron microscopy  

Microsoft Academic Search

In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved

Brett Barwick; David J. Flannigan; Ahmed H. Zewail

2009-01-01

125

Microwave energy fixation for electron microscopy.  

PubMed Central

We have demonstrated that microwave energy (MW) can be used in conjunction with chemical cross-linking agents in order to rapidly fix cell suspensions and tissue blocks for electron microscopy in 7-9 seconds. The optimal MW fixation method involved immersing tissues up to 1 cu cm in dilute aldehyde fixation and immediately irradiating the specimens in a conventional microwave oven for 9 seconds to 50 C. Ultrastructural preservation of samples irradiated by MW energy was comparable to that of the control samples immersed in aldehyde fixative for 2 hours at 25 C. Stereologic analysis showed that tissue blocks fixed by the MW fixation method did not cause organelles such as liver mitochondria and salivary gland granules to shrink or to swell. Potential applications for this new fixation technology include the investigation of rapid intracellular processes (eg, vesicular transport) and preservation of proteins that are difficult to demonstrate with routine fixation methods (eg, antigens and enzymes). Images Figure 4 Figure 5 Figure 2 Figure 3 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11

Login, G. R.; Dvorak, A. M.

1985-01-01

126

Imaging Cytoskeleton Components by Electron Microscopy  

PubMed Central

Summary The cytoskeleton is a complex of detergent-insoluble components of the cytoplasm playing critical roles in cell motility, shape generation, and mechanical properties of a cell. Fibrillar polymers-actin filaments, microtubules, and intermediate filaments- are major constituents of the cytoskeleton, which constantly change their organization during cellular activities. The actin cytoskeleton is especially polymorphic, as actin filaments can form multiple higher order assemblies performing different functions. Structural information about cytoskeleton organization is critical for understanding its functions and mechanisms underlying various forms of cellular activity. Because of the nanometer-scale thickness of cytoskeletal fibers, electron microscopy (EM) is a key tool to determine the structure of the cytoskeleton. This article describes application of rotary shadowing (or metal replica) EM for visualization of the cytoskeleton. The procedure is applicable to thin cultured cells growing on glass coverslips and consists of detergent extraction of cells to expose their cytoskeleton, chemical fixation to provide stability, ethanol dehydration and critical point drying to preserve three-dimensionality, rotary shadowing with platinum to create contrast, and carbon coating to stabilize replicas. This technique provides easily interpretable three-dimensional images, in which individual cytoskeletal fibers are clearly resolved, and individual proteins can be identified by immunogold labeling. More importantly, replica EM is easily compatible with live cell imaging, so that one can correlate the dynamics of a cell or its components, e.g., expressed fluorescent proteins, with high resolution structural organization of the cytoskeleton in the same cell.

Svitkina, Tatyana

2010-01-01

127

Quantitative Analysis of Autophagy using Advanced 3D Fluorescence Microscopy.  

PubMed

Prostate cancer is the leading form of malignancies among men in the U.S. While surgery carries a significant risk of impotence and incontinence, traditional chemotherapeutic approaches have been largely unsuccessful. Hormone therapy is effective at early stage, but often fails with the eventual development of hormone-refractory tumors. We have been interested in developing therapeutics targeting specific metabolic deficiency of tumor cells. We recently showed that prostate tumor cells specifically lack an enzyme (argininosuccinate synthase, or ASS) involved in the synthesis of the amino acid arginine(1). This condition causes the tumor cells to become dependent on exogenous arginine, and they undergo metabolic stress when free arginine is depleted by arginine deiminase (ADI)(1,10). Indeed, we have shown that human prostate cancer cells CWR22Rv1 are effectively killed by ADI with caspase-independent apoptosis and aggressive autophagy (or macroautophagy)(1,2,3). Autophagy is an evolutionarily-conserved process that allows cells to metabolize unwanted proteins by lysosomal breakdown during nutritional starvation(4,5). Although the essential components of this pathway are well-characterized(6,7,8,9), many aspects of the molecular mechanism are still unclear - in particular, what is the role of autophagy in the death-response of prostate cancer cells after ADI treatment? In order to address this question, we required an experimental method to measure the level and extent of autophagic response in cells - and since there are no known molecular markers that can accurately track this process, we chose to develop an imaging-based approach, using quantitative 3D fluorescence microscopy(11,12). Using CWR22Rv1 cells specifically-labeled with fluorescent probes for autophagosomes and lysosomes, we show that 3D image stacks acquired with either widefield deconvolution microscopy (and later, with super-resolution, structured-illumination microscopy) can clearly capture the early stages of autophagy induction. With commercially available digital image analysis applications, we can readily obtain statistical information about autophagosome and lysosome number, size, distribution, and degree of colocalization from any imaged cell. This information allows us to precisely track the progress of autophagy in living cells and enables our continued investigation into the role of autophagy in cancer chemotherapy. PMID:23665532

Changou, Chun A; Wolfson, Deanna L; Ahluwalia, Balpreet Singh; Bold, Richard J; Kung, Hsing-Jien; Chuang, Frank Y S

2013-05-03

128

National Center for Electron Microscopy user's guide. Revised.  

National Technical Information Service (NTIS)

The National Center for Electron Microscopy (NCEM) in the Materials and Chemical Sciences Division of the Lawrence Berkeley Laboratory is a high voltage electron microscope facility for ultra-high resolution or dynamic in-situ studies. This document provi...

U. Dahmen K. M. Krishnan R. Gronsky G. Thomas K. H. Westmacott

1990-01-01

129

Fully Hydrated Yeast Cells Imaged with Electron Microscopy  

PubMed Central

We demonstrate electron microscopy of fully hydrated eukaryotic cells with nanometer resolution. Living Schizosaccaromyces pombe cells were loaded in a microfluidic chamber and imaged in liquid with scanning transmission electron microscopy (STEM). The native intracellular (ultra)structures of wild-type cells and three different mutants were studied without prior labeling, fixation, or staining. The STEM images revealed various intracellular components that were identified on the basis of their shape, size, location, and mass density. The maximal achieved spatial resolution in this initial study was 32 ± 8 nm, an order of magnitude better than achievable with light microscopy on pristine cells. Light-microscopy images of the same samples were correlated with the corresponding electron-microscopy images. Achieving synergy between the capabilities of light and electron microscopy, we anticipate that liquid STEM will be broadly applied to explore the ultrastructure of live cells.

Peckys, Diana B.; Mazur, Peter; Gould, Kathleen L.; de Jonge, Niels

2011-01-01

130

Quantitative polarized light microscopy of unstained mammalian cochlear sections  

NASA Astrophysics Data System (ADS)

Hearing loss is the most common sensory deficit in the world, and most frequently it originates in the inner ear. Yet, the inner ear has been difficult to access for diagnosis because of its small size, delicate nature, complex three-dimensional anatomy, and encasement in the densest bone in the body. Evolving optical methods are promising to afford cellular diagnosis of pathologic changes in the inner ear. To appropriately interpret results from these emerging technologies, it is important to characterize optical properties of cochlear tissues. Here, we focus on that characterization using quantitative polarized light microscopy (qPLM) applied to unstained cochlear sections of the mouse, a common animal model of human hearing loss. We find that the most birefringent cochlear materials are collagen fibrils and myelin. Retardance of the otic capsule, the spiral ligament, and the basilar membrane are substantially higher than that of other cochlear structures. Retardance of the spiral ligament and the basilar membrane decrease from the cochlear base to the apex, compared with the more uniform retardance of other structures. The intricate structural details revealed by qPLM of unstained cochlear sections ex vivo strongly motivate future application of polarization-sensitive optical coherence tomography to human cochlea in vivo.

Kalwani, Neil M.; Ong, Cheng Ai; Lysaght, Andrew C.; Haward, Simon J.; McKinley, Gareth H.; Stankovic, Konstantina M.

2013-02-01

131

Axon tracking in serial block-face scanning electron microscopy  

Microsoft Academic Search

Electron microscopy is an important modality for the analysis of neuronal structures in neurobiology. We address the problem of tracking axons across large distances in volumes acquired by serial block-face scanning electron microscopy (SBFSEM). Tracking, for this application, is defined as the segmentation of an axon that spans a volume using similar features between slices. This is a challenging problem

Elizabeth Jurrus; Melissa Hardy; Tolga Tasdizen; P. Thomas Fletcher; Pavel Koshevoy; Chi-Bin Chien; Winfried Denk; Ross T. Whitaker

2009-01-01

132

Sequential scanning electron microscopy of a growing plant meristem  

Microsoft Academic Search

Summary A two-step replica technique has been developed for sequential study of the epidermal cell pattern of a living plant by scanning electron microscopy. This method is nondestructive, allows periodic high resolution observation of the same developing tissue, and can precede use of any destructive technique, such as transmission electron microscopy. The replicas can be trimmed allowing observation of occluded

M. H. Williams; P. B. Green

1988-01-01

133

Aberration-Coreected Electron Microscopy at Brookhaven National Laboratory  

SciTech Connect

The last decade witnessed the rapid development and implementation of aberration correction in electron optics, realizing a more-than-70-year-old dream of aberration-free electron microscopy with a spatial resolution below one angstrom [1-9]. With sophisticated aberration correctors, modern electron microscopes now can reveal local structural information unavailable with neutrons and x-rays, such as the local arrangement of atoms, order/disorder, electronic inhomogeneity, bonding states, spin configuration, quantum confinement, and symmetry breaking [10-17]. Aberration correction through multipole-based correctors, as well as the associated improved stability in accelerating voltage, lens supplies, and goniometers in electron microscopes now enables medium-voltage (200-300kV) microscopes to achieve image resolution at or below 0.1nm. Aberration correction not only improves the instrument's spatial resolution but, equally importantly, allows larger objective lens pole-piece gaps to be employed thus realizing the potential of the instrument as a nanoscale property-measurement tool. That is, while retaining high spatial resolution, we can use various sample stages to observe the materials response under various temperature, electric- and magnetic- fields, and atmospheric environments. Such capabilities afford tremendous opportunities to tackle challenging science and technology issues in physics, chemistry, materials science, and biology. The research goal of the electron microscopy group at the Dept. of Condensed Matter Physics and Materials Science and the Center for Functional Nanomaterials, as well as the Institute for Advanced Electron Microscopy, Brookhaven National Laboratory (BNL), is to elucidate the microscopic origin of the physical- and chemical-behavior of materials, and the role of individual, or groups of atoms, especially in their native functional environments. We plan to accomplish this by developing and implementing various quantitative electron microscopy techniques in strongly correlated electron systems and nanostructured materials. As a first step, with the support of Materials Science Division, Office of Basic Energy Science, US Department of Energy, and the New York State Office of Science, Technology, and Academic Research, recently we acquired three aberration-corrected electron microscopes from the three major microscope manufacturers, i.e., JEOL, Hitachi, and FEI. The Hitachi HD2700C is equipped with a probe corrector, the FEI Titan 80-300 has an imaging corrector, while the JEOL2200MCO has both. All the correctors are of the dual-hexapole type, designed and manufactured by CEOS GmbH based on the design due to Rose and Haider [3, 18]. All these three are one-of-a-kind in the US, designed for specialized capabilities in characterizing nanoscale structure. In this chapter, we review the performance of these state-of-the art instruments and the new challenges associated with the improved spatial resolution, including the environment requirements of the laboratory that hosts these instruments. Although each instrument we describe here has its own strengths and drawbacks, it is not our intention to rank them in terms of their performance, especially their spatial resolution in imaging.

Zhu,Y.; Wall, J.

2008-04-01

134

Electron Microscopy for Rapid Diagnosis of Emerging Infectious Agents1  

PubMed Central

Diagnostic electron microscopy has two advantages over enzyme-linked immunosorbent assay and nucleic acid amplification tests. After a simple and fast negative stain preparation, the undirected, “open view” of electron microscopy allows rapid morphologic identification and differential diagnosis of different agents contained in the specimen. Details for efficient sample collection, preparation, and particle enrichment are given. Applications of diagnostic electron microscopy in clinically or epidemiologically critical situations as well as in bioterrorist events are discussed. Electron microscopy can be applied to many body samples and can also hasten routine cell culture diagnosis. To exploit the potential of diagnostic electron microscopy fully, it should be quality controlled, applied as a frontline method, and be coordinated and run in parallel with other diagnostic techniques.

Gelderblom, Hans R.

2003-01-01

135

Quantitative Fluorescence Imaging with Laser Scanning Confocal Microscopy.  

National Technical Information Service (NTIS)

Scanning confocal microscopy (SCM) offers a dramatic instrumental advantage for fluorescence microscopy through discrimination against out-of-focus background fluorescence, through inherent resolution perpendicular to the plane of focus and improved in-pl...

K. S. Wells D. R. Sandison J. Strickler W. W. Webb

1990-01-01

136

Value of electron microscopy in the diagnosis of glomerular diseases.  

PubMed

To evaluate the contribution of electron microscopy to the final diagnosis of glomerulopathies, the authors established a prospective study during the first semester of 2006. A total of 52 kidney biopsies were performed with 3 samples for light microscopy, immunofluorescence, and electron microscopy. Among these renal biopsies, only 20 were examined with electron microscopy because the diagnosis made on the basis of conventional methods had remained unclear or doubtful. In 18 cases, electron microscopy was undertaken for the investigation of primary kidney disease. The 2 remaining cases were transplant biopsies. In this series of 20 patients, there were 3 children with an average age of 9 years and 17 adults with an average age of 35.5 years. Fifteen patients (75%) were nephrotic. The study revealed that electron microscopy was essential for diagnosis in 8 cases (40%) and was helpful in 12 cases (60%). In conclusion, the results showed that the ultrastructural study provides essential or helpful information in many cases of glomerular diseases, and therefore electron microscopy should be considered an important tool of diagnostic renal pathology. As was recommended, it is important to reserve renal tissue for ultrastructural study unless electron microscopy can be routinely used in all biopsies. Thus, this technique could be performed wherever a renal biopsy has to be ultrastructurally evaluated. PMID:20192700

Darouich, Sihem; Goucha, Rym Louzir; Jaafoura, Mohamed Habib; Moussa, Fatma Ben; Zekri, Semy; Maiz, Hédi Ben

2010-04-01

137

Silver nanoparticle-induced degranulation observed with quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

The use of AgNP is becoming more and more widespread in biomedical field. But compared with the promising bactericidal function, other physiological effects of AgNP on cells are relatively scant. In this research, we propose quantitative phase microscopy (QPM) as a new method to study the degranulation, and AgNP-induced RBL-2H3 cell degranulation is studied as well. Firstly, HeLa cells as the cell control and PBS as the solvent control, we measured the cell volume and cross section profile (x-z plane) with QPM. The results showed that the volume and cross section profile changed only the RBL-2H3 cells exposed to calcium ionophore A23187, which demonstrates the validity of QPM in degranulation research. Secondly, 50?g/mL of AgNP was used instead of A23187, and the measurement of cell volume and cross section profile was carried out again. RBL-2H3 cell volume increased immediately after AgNP was added, and cross section profile showed that the cell surface became granulated, but HeLa cell was lack of that effect. Phase images obviously indicated the RBL-2H3 cell deformation. Thirdly, stained with Fluo-3/AM, intracellular calcium Ca2+]i of single RBL-2H3 cell treated with AgNP was observed with fluorescent microscopy; incubated with AgNP for 20min, the supernatant of RBL-2H3 cells was collected and reacted with o-phthalaldehyde (OPA), then the fluorescent intensity of histamine-OPA complex was assayed with spectrofluorometer. The results of Ca2+]i and histamine increase showed that degranulation of AgNP-induced RBL-2H3 cell occurred. So, the cell volume was used as a parameter of degranulation in our study and AgNP-induced RBL-2H3 cells degranulation was confirmed by the cell volume increment, cross section profile change, and [Ca2+]i and histamine in supernatant increase.

Yang, Wenzhong; Lee, Seungrag; Lee, Jiyong; Bae, Yoonsung; Kim, Dugyoung

2010-02-01

138

Image formation modeling in cryo-electron microscopy.  

PubMed

Accurate modeling of image formation in cryo-electron microscopy is an important requirement for quantitative image interpretation and optimization of the data acquisition strategy. Here we present a forward model that accounts for the specimen's scattering properties, microscope optics, and detector response. The specimen interaction potential is calculated with the isolated atom superposition approximation (IASA) and extended with the influences of solvent's dielectric and ionic properties as well as the molecular electrostatic distribution. We account for an effective charge redistribution via the Poisson-Boltzmann approach and find that the IASA-based potential forms the dominant part of the interaction potential, as the contribution of the redistribution is less than 10%. The electron wave is propagated through the specimen by a multislice approach and the influence of the optics is included via the contrast transfer function. We incorporate the detective quantum efficiency of the camera due to the difference between signal and noise transfer characteristics, instead of using only the modulation transfer function. The full model was validated against experimental images of 20S proteasome, hemoglobin, and GroEL. The simulations adequately predict the effects of phase contrast, changes due to the integrated electron flux, thickness, inelastic scattering, detective quantum efficiency and acceleration voltage. We suggest that beam-induced specimen movements are relevant in the experiments whereas the influence of the solvent amorphousness can be neglected. All simulation parameters are based on physical principles and, when necessary, experimentally determined. PMID:23711417

Vulovi?, Miloš; Ravelli, Raimond B G; van Vliet, Lucas J; Koster, Abraham J; Lazi?, Ivan; Lücken, Uwe; Rullgård, Hans; Öktem, Ozan; Rieger, Bernd

2013-05-25

139

Silicon nitride windows for electron microscopy of whole cells.  

PubMed

Silicon microchips with thin, electron transparent silicon nitride windows provide a sample support that accommodates both light-, and electron microscopy of whole eukaryotic cells in vacuum or liquid, with minimum sample preparation steps. The windows are robust enough that cellular samples can be cultured directly onto them, with no addition of a supporting film, and there is no need to embed or section the sample, as is typically required in electron microscopy. By combining two microchips, a microfluidic chamber can be constructed for the imaging of samples in liquid in the electron microscope. We provide microchip design specifications, a fabrication outline, instructions on how to prepare the microchips for biological samples, and examples of images obtained using different light and electron microscopy modalities. The use of these microchips is particularly advantageous for correlative light and electron microscopy. PMID:21770941

Ring, E A; Peckys, D B; Dukes, M J; Baudoin, J P; de Jonge, N

2011-07-19

140

Silicon Nitride Windows for Electron Microscopy of Whole Cells  

PubMed Central

Summary Silicon microchips with thin electron transparent silicon nitride windows provide a sample support that accommodates both light-, and electron microscopy of whole eukaryotic cells in vacuum or liquid, with minimum sample preparation steps. The windows are robust enough that cellular samples can be cultured directly onto them, with no addition of a supporting film, and no need to embed or section the sample, as is typically required in electron microscopy. By combining two microchips, a microfluidic chamber can be constructed for the imaging of samples in liquid in the electron microscope. We provide microchip design specifications, a fabrication outline, instructions on how to prepare them for biological samples, and examples of images obtained using different light-, and electron microscopy modalities. The use of these microchips is particularly advantageous for correlative light-, and electron microscopy.

Ring, E. A.; Peckys, D. B.; Dukes, M. J.; Baudoin, J. P.; de Jonge, N.

2012-01-01

141

Quantitative metallography by electron backscattered diffraction.  

PubMed

Although electron backscattered diffraction (EBSD) in the scanning electron microscope is used mainly to investigate the relationship between local textures and microstructures, the technique has now developed to the stage where it requires serious consideration as a tool for routine quantitative characterization of microstructures. This paper examines the application of EBSD to the characterization of phase distributions, grain and subgrain structures and also textures. Comparisons are made with the standard methods of quantitative metallography and it is shown that in many cases EBSD can produce more accurate and detailed measurements than the standard methods and that the data may sometimes be obtained more rapidly. The factors which currently limit the use of EBSD for quantitative microstructural characterization, including the speed of data acquisition and the angular and spatial resolutions, are discussed, and future developments are considered. PMID:10460682

Humphreys

1999-09-01

142

Quantitative Analysis by Auger Electron Spectroscopy  

Microsoft Academic Search

A short review is presented of the theoretical background of a physical model for the quantification of Auger electron spectroscopy (AES) for surface analysis. The recent studies on the data-base for the inelastic mean free paths (IMFP) by Seah and Dench and systematic calculations of the backscattering factors (R) by Shimizu and Ichimura have now enabled standard quantitative corrections comparable

Ryuichi Shimizu

1983-01-01

143

Near-infrared branding efficiently correlates light and electron microscopy.  

PubMed

The correlation of light and electron microscopy of complex tissues remains a major challenge. Here we report near-infrared branding (NIRB), which facilitates such correlation by using a pulsed, near-infrared laser to create defined fiducial marks in three dimensions in fixed tissue. As these marks are fluorescent and can be photo-oxidized to generate electron contrast, they can guide re-identification of previously imaged structures as small as dendritic spines by electron microscopy. PMID:21642966

Bishop, Derron; Niki?, Ivana; Brinkoetter, Mary; Knecht, Sharmon; Potz, Stephanie; Kerschensteiner, Martin; Misgeld, Thomas

2011-06-05

144

Electron microscopy of heavy metal waste in cement matrices  

Microsoft Academic Search

Ordinary Portland cements mixed with various amounts of chromium metal in the form of nitrates (Cr(NO3)3), to simulate industrial waste, have been studied by electron microscopy techniques, i.e. scanning electron and scanning transmission electron microscopy. Trivalent chromium was found to be chemically incorporated in all hydrated cement phases, and appeared to substitute for silicon in calcium silicate hydrate (C-S-H), which

D. G. Ivey; R. B. Heimann; M. Neuwirth; S. Shumborski; D. Conrad; R. J. Mikula; W. W. Lam

1990-01-01

145

Microscopic analysis of DNA and DNA-protein assembly by transmission electron microscopy, scanning tunneling microscopy and scanning force microscopy.  

PubMed

To investigate DNA and DNA-protein assembly, nucleic acids were adsorbed to freshly cleaved mica in the presence of magnesium ions. The efficiency of DNA adhesion and the distribution of the molecules on the mica surface were checked by transmission electron microscopy. In addition, various kinds of DNA-protein interactions including DNA wrapping and DNA supercoiling were analyzed using electron microscopy. In parallel, this Mg2+/mica method can be applied (1) to analyze embedded DNA by scanning tunneling microscopy, (2) to visualize freeze-dried, metal coated DNA-protein complexes by tunneling microscopy, and (3) to image DNA or DNA-protein interaction in air or in liquid by scanning force microscopy. An advantage of such a correlative approach is that parallel imaging can reveal complementary information. The benefit of such a combined approach in analysis of protein-induced DNA bending is discussed. PMID:9601534

Müller-Reichert, T; Gross, H

1996-01-01

146

Generation of Electron beam probe in Scanning Electron Microscopy  

Microsoft Academic Search

The electron column consists of an electron gun, one object lens and two condenser lenses. The electron gun produces a source of electrons and accelerates these electrons to an energy in the range 1-30 keV. Electron lenses are used to reduce the diameter of this source of electrons and place a small, focused electron beam on the specimen. Electron probe

Sun-Jong Lim; Chang-Hong Lee

2008-01-01

147

Modern uses of electron microscopy for detection of viruses.  

PubMed

Electron microscopy, considered by some to be an old technique, is still on the forefront of both clinical viral diagnoses and viral ultrastructure and pathogenesis studies. In the diagnostic setting, it is particularly valuable in the surveillance of emerging diseases and potential bioterrorism viruses. In the research arena, modalities such as immunoelectron microscopy, cryo-electron microscopy, and electron tomography have demonstrated how viral structural components fit together, attach to cells, assimilate during replication, and associate with the cellular machinery during replication and egression. These studies provide information for treatment and vaccine strategies. PMID:19822888

Goldsmith, Cynthia S; Miller, Sara E

2009-10-01

148

Electron microscopy study of zeolite ZK-14; a synthetic chabazite  

NASA Astrophysics Data System (ADS)

The defect structure of zeolite (K+, TMA+) — ZK-14, a synthetic chabazite, has been studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM together with TEM bright field (BF) and dark field (DF) micrographs indicate that the hexagonal, platelet ZK-14 crystals are built up of crystalline blocks joined by twinning along (00.1). High resolution transmission electron microscopy (HRTEM) reveals faulting of the ideal AABBCC single 6-ring stacking sequence of ZK-14. This is consistent with an observed line broadening in its X-ray powder diffraction profile. Channel apertures are imaged, even for thick specimens.

Cartlidge, S.; Wessicken, R.; Nissen, H.-U.

1983-03-01

149

Near Field-Emission Scanning Electron Microscopy with Energy Analysis  

NASA Astrophysics Data System (ADS)

We report on new results about near field-emission scanning electron microscopy (NFESEM) which emphasize the potential of generating secondary electrons using a primary electron beam of low energy electrons. Based on scanning tunneling microscopy technology NFESEM uses a sharp W-tip as a cold field emitter, which scans the surface at constant distance, usually in the range of 5 to 40 nm. An applied voltage between tip and sample induces field emission at the tip. These primary electrons are then accelerated towards the target and successively scattered by its surface generating secondary electrons. The last ones, which carry information of the sample, are emitted and energy analyzed. Spatially resolved analysis of energy and polarization of secondary electrons may provide new insight into surface microscopy.

Zanin, Danilo Andrea; de Pietro, Lorenzo Giuseppe; Cabrera, Hugo; Thalmann, Peter; Redmann, Anna-Lena; Ramsperger, Urs; Pescia, Danilo; Erbudak, Mehmet

2013-03-01

150

In Situ Analytical Electron Microscopy for Probing Nanoscale Electrochemistry  

SciTech Connect

Oxides and their tailored structures are at the heart of electrochemical energy storage technologies and advances in understanding and controlling the dynamic behaviors in the complex oxides, particularly at the interfaces, during electrochemical processes will catalyze creative design concepts for new materials with enhanced and better-understood properties. Such knowledge is not accessible without new analytical tools. New innovative experimental techniques are needed for understanding the chemistry and structure of the bulk and interfaces, more importantly how they change with electrochemical processes in situ. Analytical Transmission Electron Microscopy (TEM) is used extensively to study electrode materials ex situ and is one of the most powerful tools to obtain structural, morphological, and compositional information at nanometer scale by combining imaging, diffraction and spectroscopy, e.g., EDS (energy dispersive X-ray spectrometry) and Electron Energy Loss Spectrometry (EELS). Determining the composition/structure evolution upon electrochemical cycling at the bulk and interfaces can be addressed by new electron microscopy technique with which one can observe, at the nanometer scale and in situ, the dynamic phenomena in the electrode materials. In electrochemical systems, for instance in a lithium ion battery (LIB), materials operate under conditions that are far from equilibrium, so that the materials studied ex situ may not capture the processes that occur in situ in a working battery. In situ electrochemical operation in the ultra-high vacuum column of a TEM has been pursued by two major strategies. In one strategy, a 'nano-battery' can be fabricated from an all-solid-state thin film battery using a focused ion beam (FIB). The electrolyte is either polymer based or ceramic based without any liquid component. As shown in Fig. 1a, the interfaces between the active electrode material/electrolyte can be clearly observed with TEM imaging, in contrast to the composite electrodes/electrolyte interfaces in conventional lithium ion batteries, depicted in Fig.1b, where quantitative interface characterization is extremely difficult if not impossible. A second strategy involves organic electrolyte, though this approach more closely resembles the actual operation conditions of a LIB, the extreme volatility In Situ Analytical Electron Microscopy for Probing Nanoscale Electrochemistry by Ying Shirley Meng, Thomas McGilvray, Ming-Che Yang, Danijel Gostovic, Feng Wang, Dongli Zeng, Yimei Zhu, and Jason Graetz of the organic electrolytes present significant challenges for designing an in situ cell that is suitable for the vacuum environment of the TEM. Significant progress has been made in the past few years on the development of in situ electron microscopy for probing nanoscale electrochemistry. In 2008, Brazier et al. reported the first cross-section observation of an all solid-state lithium ion nano-battery by TEM. In this study the FIB was used to make a 'nano-battery,' from an all solid-state battery prepared by pulsed laser deposition (PLD). In situ TEM observations were not possible at that time due to several key challenges such as the lack of a suitable biasing sample holder and vacuum transfer of sample. In 2010, Yamamoto et al. successfully observed changes of electric potential in an all-solid-state lithium ion battery in situ with electron holography (EH). The 2D potential distribution resulting from movement of lithium ions near the positive-electrode/electrolyte interface was quantified. More recently Huang et al. and Wang et al. reported the in situ observations of the electrochemical lithiation of a single SnO{sub 2} nanowire electrode in two different in situ setups. In their approach, a vacuum compatible ionic liquid is used as the electrolyte, eliminating the need for complicated membrane sealing to prevent the evaporation of carbonate based organic electrolyte into the TEM column. One main limitation of this approach is that EELS spectral imaging is not possible due to the high plasmon signal of the ionic li

Graetz J.; Meng, Y.S.; McGilvray, T.; Yang, M.-C.; Gostovic, D.; Wang, F.; Zeng, D.; Zhu, Y.

2011-10-31

151

The use of markers for correlative light electron microscopy.  

PubMed

Bioimaging: the visualisation, localisation and tracking of movement of specific molecules in cells using microscopy has become an increasing field of interest within life science research. For this, the availability of fluorescent and electron-dense markers for light and electron microscopy, respectively, is an essential tool to attach to the molecules of interest. In recent years, there has been an increasing effort to combine light and electron microscopy in a single experiment. Such correlative light electron microscopy (CLEM) experiments thus rely on using markers that are both fluorescent and electron dense. Unfortunately, there are very few markers that possess both these properties. Markers for light microscopy such as green fluorescent protein are generally not directly visible in the electron microscopy and vice versa for gold particles. Hence, there has been an intensive search for markers that are directly visible both in the light microscope and in the electron microscope. Here we discuss some of the strategies and pitfalls that are associated with the use of CLEM markers, which might serve as a "warning" that new probes should be extensively tested before use. We focus on the use of CLEM markers for the study of intracellular transport and specifically endocytosis. PMID:20524017

Brown, Edward; Verkade, Paul

2010-06-05

152

Scanning electron microscopy of acantholysis in pemphigus foliaceus*  

PubMed Central

We performed scanning electron microscopy of an inverted blister roof in a case of pemphigus foliaceus. The loss of intercellular adherence could be easily seen with low magnification. The acantholytic keratinocytes displayed an irregular and sometimes polygonal contour. Round cells, typically seen in light microscopy, were also observed. The examination of a blister roof allows ultrastructural documentation of the acantholytic changes.

de Almeida, Hiram Larangeira; Leitao, Aline Hatzenberger; Rossi, Gabriela; Rocha, Nara Moreira; Silva, Ricardo Marques e

2013-01-01

153

Some Applications of Microanalytical Electron Microscopy in Materials Research.  

National Technical Information Service (NTIS)

Electron microscopy has made extraordinary progress over the past 30 years and has become an indispensible tool for research in materials science. In this paper a review is given of some applications of microdiffraction and microanalysis in our current ma...

G. Thomas

1985-01-01

154

Outcome of the First Electron Microscopy Validation Task Force Meeting  

PubMed Central

This Meeting Review describes the proceedings and conclusions from the inaugural meeting of the Electron Microscopy Validation Task Force organized by the Unified Data Resource for 3DEM (http://www.emdatabank.org) and held at Rutgers University in New Brunswick, NJ on September 28 and 29, 2010. At the workshop, a group of scientists involved in collecting electron microscopy data, using the data to determine three-dimensional electron microscopy (3DEM) density maps, and building molecular models into the maps explored how to assess maps, models, and other data that are deposited into the Electron Microscopy Data Bank and Protein Data Bank public data archives. The specific recommendations resulting from the workshop aim to increase the impact of 3DEM in biology and medicine.

Henderson, Richard; Sali, Andrej; Baker, Matthew L.; Carragher, Bridget; Devkota, Batsal; Downing, Kenneth H.; Egelman, Edward H.; Feng, Zukang; Frank, Joachim; Grigorieff, Nikolaus; Jiang, Wen; Ludtke, Steven J.; Medalia, Ohad; Penczek, Pawel A.; Rosenthal, Peter B.; Rossmann, Michael G.; Schmid, Michael F.; Schroder, Gunnar F.; Steven, Alasdair C.; Stokes, David L.; Westbrook, John D.; Wriggers, Willy; Yang, Huanwang; Young, Jasmine; Berman, Helen M.; Chiu, Wah; Kleywegt, Gerard J.; Lawson, Catherine L.

2012-01-01

155

Microscopic World: A Demonstration of Electron Microscopy for Younger Students.  

National Technical Information Service (NTIS)

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 micros...

L. L. Horton

1992-01-01

156

EMMPDL: An Electron Microscopy and Microanalysis Public Domain Library.  

National Technical Information Service (NTIS)

As personal computers become more and more prolific it becomes inevitable that programs and/or generic subroutines useful in both electron microscopy and microanalysis are rewritten or redeveloped a great number of times for a range of different languages...

N. J. Zaluzec

1987-01-01

157

Examination of Polysulfide Sealants by Scanning Electron Microscopy.  

National Technical Information Service (NTIS)

A procedure was developed for the examination of polysulfide sealants by scanning electron microscopy. This procedure was applied to manganese dioxide and dichromate-cured elastomers. Calcium carbonate filler was identified in both types of sealants and t...

W. Mazurek V. M. Silva

1987-01-01

158

Transmission Electron Microscopy of Rapidly Solidified Du-5% W Alloy.  

National Technical Information Service (NTIS)

Rapidly solidified depleted uranium alloys containing 5% tungsten have been characterized. Transmission electron microscopy work on depleted uranium-tungsten alloys reveals that tungsten is precipitated out in the form of fine dispersion and that these di...

R. Batra

1991-01-01

159

Electron Microscopy of Elastomers Containing In-situ Precipitated Silica.  

National Technical Information Service (NTIS)

Transmission electron microscopy is used to characterize reinforcing silica particles precipitated as filler into networks of poly(dimethylsiloxane) by the hydrolysis of tetraethylorthosilicate. Particle diameters were typically 200 A, with relatively nar...

J. E. Mark Y. P. Ning J. Tang M. Y. Tang

1985-01-01

160

Axon Tracking in Serial Block-Face Scanning Electron Microscopy  

Microsoft Academic Search

Electron microscopy is an important modality for the analysis of neuronal structures in neurobiology. We address the problem of tracking axons across large distances in volumes acquired by Serial Block-Face Scanning Electron Microscopy (SBFSEM). This is a challenging problem due to the small cross- sectional size of axons and the low signal-to-noise ratio in SBF- SEM images. A carefully engineered

Elizabeth Jurrus; Tolga Tasdizen; Pavel Koshevoy; P. Thomas Fletcher; Melissa Hardy; Chi-Bin Chien; Winfried Denk; Ross Whitaker

2006-01-01

161

Transmission electron microscopy characterisation of 0-D nanomaterials  

NASA Astrophysics Data System (ADS)

When materials are scaled down to the nanometre level, a change in physical behaviour is frequently observed. In so-called 0-D nanomaterials (nanoparticles), these unique nanoscale properties are most abundant and are usually linked to either a change in (electronic) structure of the material or to the dominating influence of the particle surface at the nanometre scale. In this doctoral work the nanoscale properties of several nanoparticle systems have been studied using advanced transmission electron microscopy (TEM). Every material that was studied required for its solution a unique approach and a host of transmission electron microscopy techniques. The title of this doctoral work can be freely translated as "retrieving quantitatively the maximal and most accurate chemical, structural and morphological information from nanoparticles by advanced transmission electron microscopy, to uncover and explain their unique properties". Chapter 1 gives a brief general introduction to the world of nanomaterials and nanotechnology in general and more specifically to 0-D nanomaterials (nanoparticles). The unique properties and potential applications of these materials are described. The production of 0-D nanomaterials is not covered in this chapter, as this is an extremely broad field to cover in only a few pages. Instead, the production method for each of the materials is left to the detailed chapters that follow. In Chapter 2 the main transmission electron microscopy techniques used to characterise the materials in the further chapters are described together with the microscopes used to perform these techniques and their parameters of operation. Again, the sample-specific setups are listed in the detailed chapters that follow. Chapter 3 covers all work carried out on luminescent detonation nanodiamond powder for drug delivery and bio-medical imaging applications. Specific attention is paid to the morphology, surface chemistry and nitrogen incorporation of detonation nanodiamond particles cleaned by novel routes, and the possibility of production of luminescent N-V centres within the diamond nanoparticles is studied. Chapter 4 deals with self-arranged Co nanoparticle arrays, so-called superlattices. By closely studying the oxidation behaviour of such arrays, a new intrinsic property has been discovered: enhanced stability against oxidation of self-arranged cobalt nanoparticles. This intriguing physical behaviour of arranged cobalt nanoparticles has never been observed before. Chapter 5 describes and discusses all results obtained from TEM investigation of hybrid nanoporous-nanoparticle materials for advanced catalysis applications: first, the possibilities of TEM for the characterisation of the metal MOF material family; and second, the example of Au ZIF. Finally, in Chapter 6, assisted spray-pyrolysis generated ZnO nanoparticles are studied. The ZnO nanomaterial produced by a novel assisted spray pyrolysis method is compared to conventionally spray pyrolysed ZnO nanomaterials. The influence of assisted spray pyrolysis production on the size, morphology and optical properties (UV blocking capabilities) of the ZnO nanoparticles is studied for the case of citric-acid assisted spray pyrolysis.

Turner, Stuart Matthew

162

Advanced Correlative Light/Electron Microscopy: Current Methods and New Developments Using Tokuyasu Cryosections  

PubMed Central

Microscopy is an essential tool for analysis of cellular structures and function. With the advent of new fluorescent probes and super-resolution light microscopy techniques, the study of dynamic processes in living cells has been greatly facilitated. Fluorescence light microscopy provides analytical, quantitative, and three-dimensional (3D) data with emphasis on analysis of live cells using fluorescent markers. Sample preparation is easy and relatively inexpensive, and the use of appropriate tags provides the ability to track specific proteins of interest. Of course, only electron microscopy (EM) achieves the highest definition in terms of ultrastructure and protein labeling. To fill the gap between light microscopy and EM, correlative light and electron microscopy (CLEM) strategies have been developed. In particular, hybrid techniques based upon immuno-EM provide sensitive protein detection combined with high-resolution information on cell structures and protein localization. By adding the third dimension to EM with electron tomography (ET) combined with rapid freezing, CLEM techniques now provide additional tools for quantitative 3D analysis. Here, we overview the major methods applied and highlight the latest advances in the field of CLEM. We then focus on two selected techniques that use cryosections as substrate for combined biomolecular imaging. Finally, we provide a perspective of future developments in the field. (J Histochem Cytochem 57:1103–1112, 2009)

Cortese, Katia; Diaspro, Alberto; Tacchetti, Carlo

2009-01-01

163

Chromatic Confocal Electron Microscopy with a Finite Pinhole Size  

NASA Astrophysics Data System (ADS)

Scanning confocal electron microscopy (SCEM) is a new imaging mode in electron microscopy. Spherical aberration corrected electron microscope instruments fitted with two aberration correctors can be used in this mode which provides improved depth resolution and selectivity compared to optical sectioning in a conventional scanning transmission geometry. In this article, we consider the depth resolution and energy resolution in the confocal optical configuration for SCEM using inelastically scattered electrons with a finite pinhole size. We experimentally demonstrate energy-filtered optical sectioning in a double aberration-corrected instrument with uncorrected chromatic aberration without using a dedicated energy filter.

Wang, P.; Kirkland, A. I.; Nellist, P. D.

2012-07-01

164

Atmospheric scanning electron microscope for correlative microscopy.  

PubMed

The JEOL ClairScope is the first truly correlative scanning electron and optical microscope. An inverted scanning electron microscope (SEM) column allows electron images of wet samples to be obtained in ambient conditions in a biological culture dish, via a silicon nitride film window in the base. A standard inverted optical microscope positioned above the dish holder can be used to take reflected light and epifluorescence images of the same sample, under atmospheric conditions that permit biochemical modifications. For SEM, the open dish allows successive staining operations to be performed without moving the holder. The standard optical color camera used for fluorescence imaging can be exchanged for a high-sensitivity monochrome camera to detect low-intensity fluorescence signals, and also cathodoluminescence emission from nanophosphor particles. If these particles are applied to the sample at a suitable density, they can greatly assist the task of perfecting the correlation between the optical and electron images. PMID:22857935

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

2012-01-01

165

[Electron microscopy study of artificial vitreous gel].  

PubMed

Artificial gels prepared from Cu2+-ions and hyaluronic acid were studied in the electron microscope and compared with the native vitreous body. Additionally, the authors attempted to produce transparent gels from the native constituents of the vitreous body, namely collagen and hyaluronic acid. Mixing of solutions of these constituents formed no gels but white precipitates. The ultrastructure of these precipitates was also studied in the electron microscope. PMID:3723971

Ehgartner, E M; Schmut, O; Hofmann, H

1986-04-01

166

Scanning Electron and Phase-Contrast Microscopy of Bacterial Spores  

PubMed Central

The three-dimensional immages of free and intrasporangial spores produced by scanning electron microscopy show surface structures not visible by phase-contrast microscopy. Although fine surface detail is not elucidated by scanning electron microscopy, this technique does afford a definitive picture of the general shape of spores. Spores of Bacillus popilliae, B. lentimorbus, B. thuringiensis, B. alvei, B. cereus, and Sarcina ureae have varying patterns of surface ridge formation, whereas spores of B. larvae, B. subtilis, and B. licheniformis have relatively smooth surfaces. Images

Bulla, L. A.; Julian, G. St.; Rhodes, R. A.; Hesseltine, C. W.

1969-01-01

167

Electron Microscopy of Biological Materials at the Nanometer Scale  

NASA Astrophysics Data System (ADS)

Electron microscopy of biological matter uses three different imaging modalities: (a) electron crystallography, (b) single-particle analysis, and (c) electron tomography. Ideally, these imaging modalities are applied to frozen-hydrated samples to ensure an optimal preservation of the structures under scrutiny. Cryo-electron microscopy of biological matter has made important advances in the past decades. It has become a research tool that further expands the scope of structural research into unique areas of cell and molecular biology, and it could augment the materials research portfolio in the study of soft and hybrid materials. This review addresses how researchers using transmission electron microscopy can derive structural information at high spatial resolution from fully hydrated specimens, despite their sensitivity to ionizing radiation, despite the adverse conditions of high vacuum for samples that have to be kept in aqueous environments, and despite their low contrast resulting from weakly scattering building blocks.

Kourkoutis, Lena Fitting; Plitzko, Jürgen M.; Baumeister, Wolfgang

2012-08-01

168

High resolution electron spin resonance microscopy  

NASA Astrophysics Data System (ADS)

NMR microscopy is routinely employed in fields of science such as biology, botany, and materials science to observe magnetic parameters and transport phenomena in small scale structures. Despite extensive efforts, the resolution of this method is limited (>10?m for short acquisition times), and thus cannot answer many key questions in these fields. We show, through theoretical prediction and initial experiments, that ESR microscopy, although much less developed, can improve upon the resolution limits of NMR, and successfully undertake the 1?m resolution challenge. Our theoretical predictions demonstrate that existing ESR technology, along with advanced imaging probe design (resonator and gradient coils), using solutions of narrow linewidth radicals (the trityl family), should yield 64×64 pixels 2D images (with z slice selection) with a resolution of 1×1×10?m at ~60GHz in less than 1h of acquisition. Our initial imaging results, conducted by CW ESR at X-band, support these theoretical predictions and already improve upon the previously reported state-of-the-art for 2D ESR image resolution achieving ~10×10?m, in just several minutes of acquisition time. We analyze how future progress, which includes improved resonators, increased frequency of measurement, and advanced pulsed techniques, should achieve the goal of micron resolution.

Blank, Aharon; Dunnam, Curt R.; Borbat, Peter P.; Freed, Jack H.

2003-11-01

169

Multimodal dyes: toward correlative two-photon and electron microscopy  

NASA Astrophysics Data System (ADS)

Nowadays, many crucial biological questions involve the observation of biological samples at different scales. Thus, optical microscopy can be associated to magnetic nuclear imaging allowing access to data from the cellular to the organ level, or can be associated to electron microscopy to reach the sub cellular level. We will describe here the design, synthesis and characterization of new bimodal probes, which can be used as dye in two-photon excited microscopy (TPEM) and electron dense markers in scanning and transmission electron microscopy (EM). In a first part, we will describe new molecular dyes with small organic systems grafted on metal atoms (Pt, Au). Such systems show good twophoton induced fluorescence and two-photon images of HeLa cells will be presented. In a second part, we will present hybrid organic-inorganic fluorescent systems with diketopyrrolopyrole-based dye grafted on iron oxide-silica core shell nanoparticles by peptide bond. Such systems present high two-photon absorption cross sections and good fluorescence quantum yields. These nanoparticles are rapidly internalized in HeLa cells and high quality two-photon images were performed with low laser power. Then we will present our results on correlative light-electron microscopy were twophoton and electron microscopy (both scanning and transmission) images were obtained on the same biological sample.

Bolze, Frédéric; Ftouni, Hussein; Nicoud, Jean-François; Leoni, Piero; Schwab, Yannick; Rehspringer, Jean-Luc; Mafouana, Rodrigues R.

2013-03-01

170

Atmospheric pressure scanning transmission electron microscopy  

SciTech Connect

Scanning transmission electron microscope (STEM) images of gold nanoparticles (2.1 nm average diameter) at atmospheric pressure have been recorded through a 0.36 mm thick mixture of CO, O2 and He. This was accomplished using a reaction cell consisting of two electron-transparent silicon nitride membranes mounted on a specially designed specimen rod. Gas flow occurred through plastic tubing from the outside of the microscope to the specimen region and back. Gold nanoparticles of a full width half maximum diameter of 1.0 nm were visible above the background noise and the achieved resolution was 0.5 nm in accordance with calculations of the beam broadening.

De Jonge, Niels [ORNL; Veith, Gabriel M [ORNL; Bigelow, Wilbur C [ORNL

2010-01-01

171

Quantifying nanoscale order in amorphous materials via fluctuation electron microscopy  

NASA Astrophysics Data System (ADS)

Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function extracted from diffraction data appears entirely amorphous. The variable resolution form of the technique can reveal the characteristic decay length over which topological order persists in amorphous materials. By changing the resolution, a characteristic length is obtained without the need for a priori knowledge of the structure. However, it remains a formidable challenge to invert the FEM data into a quantitative description of the structure that is free from error due to experimental noise and quantitative in both size and volume fraction. Here, we quantify the FEM method by (i) forward simulating the FEM data from a family of high quality atomistic a-Si models, (ii) reexamining the statistical origins of contributions to the variance due to artifacts, and (iii) comparing the measured experimental data with model simulations. From simulations at a fixed resolution, we show that the variance V( k) is a complex function of the size and volume fraction of the ordered regions present in the amorphous matrix. However, the ratio of the variance peaks as a function of diffraction vector k affords the size of the ordered regions; and the magnitude of the variance affords a quantitative measure of the volume fraction. From comparison of measured characteristic length with model simulations, we are able to estimate the size and volume fraction of ordered regions. The use of the STEM mode of FEM offers significant advantages in identifying artifacts in the variances. Artifacts, caused by non-idealities in the sample unrelated to nanoscale order, can easily dominate the measured variance, producing erroneous results. We show that reexamination and correction of the contributions of artifacts to variance is necessary to obtain an accurate and quantitative description of the structure of amorphous materials. Using variable resolution FEM we are able to extract a characteristic length of ordered regions in two different amorphous silicon samples. Having eliminated the noise contribution to the variance, we show here the first demonstration of a consistent characteristic length at all values of k. The experimental results presented here are the first to be consistent with both FEM theory and simulations.

Bogle, Stephanie Nicole

172

Quantitative ellipsometric microscopy at the silicon-air interface  

SciTech Connect

Ellipsometric microscopy is a technique that combines the merits of ellipsometry and light microscopy, i.e., it allows noninvasive, label-free measurements of thin film thickness and refractive index at high lateral resolution. Here we give a detailed description of the technique including a complete calibration scheme and a model to correct for the instrumental polarization of the imaging optics. The performance of the instrument was studied experimentally. We found a lateral resolution of 1 {mu}m and an absolute height accuracy of 3 nm. The measured refractive indices were accurate to 2.3% and the height sensitivity of the instrument was smaller than 5 A. Another virtue of the instrument design besides its good performance is that it is in essence an extension of standard light microscopy and could be integrated into commercial microscopes.

Linke, F.; Merkel, R. [Institut fuer Schichten und Grenzflaechen, Institut 4: Biologische Schichten (ISG4), Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

2005-06-15

173

Electron Microscopy of Hydride Precipitation in Vanadium  

Microsoft Academic Search

Precipitation of hydride from the solid solution of vanadium-hydrogen containing a small amount of hydrogen was observed at temperatures ranging between 300 K and 77 K using the cold stage of a 500 kV electron microscope. Two types of precipitates were found at low temperatures. One has a cubic superstructure with a unit cell twice as large as that of

Toshinobu Chiba; Shigeo Takano

1971-01-01

174

Transmission electron microscopy of the bacterial nucleoid  

Microsoft Academic Search

Water-containing biological material cannot withstand the vacuum of the transmission electron microscope. The classical solution to this problem has been to dehydrate chemically fixed biological samples and then embed them in resin. During such treatment, the bacterial nucleoid is especially prone to aggregation, which affects its global shape and fine structure. Initial attempts to deal with aggregation by optimizing chemical

Mikhail Eltsov; Benoît Zuber

2006-01-01

175

Scanning Electron Microscopy Studies of Dental Enamel.  

National Technical Information Service (NTIS)

Samples of sound, untreated enamel and enamel subjected to a number of different treatment procedures were selected for this study, to determine the potential of the scanning electron micro-scope as applied to the study of dental tissue. Sound enamel spec...

S. Hoffman W. S. McEwan C. M. Drew

1968-01-01

176

Electron microscopy of undecalcified human bone  

Microsoft Academic Search

An alternative approach for the electron microscopical examination of undecalcified human bone was investigated. The method required bone to be chilled to -70 degrees C, sectioned at 10 microns in a special bone cryostat, and these sections to be fixed and embedded for ultrathin sectioning. Good preservation of bone cells was seen. The advantages of this method are that it

R A Dodds; I Shore; J Moss

1988-01-01

177

Snow crystal imaging using scanning electron microscopy: I. Precipitated snow  

Microsoft Academic Search

Low-temperature scanning electron microscopy (SEM) was used to observe precipitated snow crystals. The newly-fallen snow crystals were obtained in storms at Beltsville, Maryland, and at Bearden Mountain near Davis, West Virginia, USA. The snow samples were mounted on modified SEM stubs, frozen in liquid nitrogen, sputter coated with platinum, and imaged with an electron beam. Many types of precipitated snow

A. RANGO; W. P. WERGIN; E. F. ERBE

178

National Center for Electron Microscopy: User's Guide (Revised).  

National Technical Information Service (NTIS)

The National Center for Electron Microscopy (NCEM) in the Materials and Chemical Sciences Division of the Lawrence Berkeley Laboratory is a high voltage electron microscope facility for ultra-high resolution or dynamic in-situ studies. It is supported by ...

1989-01-01

179

Electron microscopy and diffraction of layered, superconducting intercalation complexes.  

PubMed

Several layered, transition metal dichalcogenide intercalation complexes with unique superconducting properties have been examined by high-resolution electron microscopy and electron diffraction. Details of the crystalline lattice and of the lattice imperfections have been directly resolved. The results can be correlated with the available x-ray diffraction and chemical data, and they confirm and extend the postulated models. PMID:17745743

Fernández-Morán, H; Ohstuki, M; Hibino, A; Hough, C

1971-10-29

180

The application of scanning electron microscopy to fractography  

Microsoft Academic Search

Many failures involve fracture, and determination of the fracture process is a key factor in understanding the failure. This is frequently accomplished by characterizing the topography of the fracture surface. Scanning electron microscopy has a prominent role in fractography due to three features of the scanning electron microscope (SEM): high resolution, great depth of field, and the ability to obtain

C. R. Brooks; B. L. McGill

1994-01-01

181

Microangiopathy in Chronic Venous Insufficiency: Quantitative Assessment by Capillary Microscopy  

Microsoft Academic Search

Background: patients with lipodermatosclerosis (LDS) due to chronic venous disease (CVD) of the lower limb show proliferation and convolution of their skin capillaries. There has been no previous attempt to quantify the severity of venous disease according to the extent of morphological change.Aim: to quantify capillary damage in patients with CVD using capillary microscopy.Method: 132 patients attending the vascular clinic

M. H. Howlader; P. D. Coleridge Smith

2003-01-01

182

Fibrin architecture in clots: A quantitative polarized light microscopy analysis  

Microsoft Academic Search

article i nfo Article history: Fibrin plays a vital structural role in thrombus integrity. Thus, the ability to assess fibrin architecture has a potential to provide insight into thrombosis and thrombolysis. Fibrin has an anisotropic molecular structure, which enables it to be seen with polarized light. Therefore, we aimed to determine if automated polarized light microscopy methods of quantifying two

Peter Whittaker; Karin Przyklenk

2009-01-01

183

Electron microscopy investigations of ferrous martensites  

Microsoft Academic Search

This paper is concerned with electron metallography of bcc or bet ferrous martensite in which particular attention is paid\\u000a to, the characterization of substructures., The transformation substructure is complex and new results are reported on multiple\\u000a {112} twinning. The factors controlling the martensitic substructure are evaluated and it is concluded that the strength and\\u000a deformation, characteristics of martensite are the

Gareth Thomas

1971-01-01

184

Simple ultramicro-pipette for electron microscopy  

Microsoft Academic Search

A design for an ultramicro-pipette which permits the controlled delivery of droplets down to 2 ? in diameter is described. After measurement by means of a screw-micrometer eyepiece, the droplets are deposited directly upon film-covered electron-microscope grids by means of a micro-manipulator. This technique allows particle counts of suspensions of submicroscopic particles to be made with greatly increased precision.

R. Hardy; J. R. Majer; S. Travers

1960-01-01

185

Total internal reflection holographic microscopy for quantitative phase characterization of cellular adhesion  

NASA Astrophysics Data System (ADS)

A new form of near-field microscopy is presented using digital holography for quantitative phase imagery and characterization of cell-substrate interfaces. This imaging technique, termed total internal reflection holographic microscopy (TIRHM), utilizes an evanescent wave phase shift from the presence of cellular organisms, membranes, adhesions, and tissue structures on a prism face in order to modulate an object beam wavefront in a digital holographic microscope. Quantitative phase images of live cellular specimens are presented.

Ash, William M., III; Clark, David; Lo, Chun-Min; Kim, Myung K.

2010-02-01

186

Novel Application of Fluorescence Lifetime and Fluorescence Microscopy Enables Quantitative Access to Subcellular Dynamics in Plant Cells  

PubMed Central

Background Optical and spectroscopic technologies working at subcellular resolution with quantitative output are required for a deeper understanding of molecular processes and mechanisms in living cells. Such technologies are prerequisite for the realisation of predictive biology at cellular and subcellular level. However, although established in the physical sciences, these techniques are rarely applied to cell biology in the plant sciences. Principal Findings Here, we present a combined application of one-chromophore fluorescence lifetime microscopy and wavelength-selective fluorescence microscopy to analyse the function of a GFP fusion of the Brassinosteroid Insensitive 1 Receptor (BRI1-GFP) with high spatial and temporal resolution in living Arabidopsis cells in their tissue environment. We show a rapid, brassinolide-induced cell wall expansion and a fast BR-regulated change in the BRI1-GFP fluorescence lifetime in the plasmamembrane in vivo. Both cell wall expansion and changes in fluorescence lifetime reflect early BR-induced and BRI1-dependent physiological or signalling processes. Our experiments also show the potential of one-chromophore fluorescence lifetime microscopy for the in vivo monitoring of the biochemical and biophysical subcellular environment using GFP fusion proteins as probes. Significance One-chromophore fluorescence lifetime microscopy, combined with wavelength-specific fluorescence microscopy, opens up new frontiers for in vivo dynamic and quantitative analysis of cellular processes at high resolution which are not addressable by pure imaging technologies or transmission electron microscopy.

Elgass, Kirstin; Caesar, Katharina; Schleifenbaum, Frank; Stierhof, York-Dieter; Meixner, Alfred J.; Harter, Klaus

2009-01-01

187

Quantitative WDS analysis using electron probe microanalyzer  

SciTech Connect

In this paper, the procedure for conducting quantitative elemental analysis by ZAF correction method using wavelength dispersive X-ray spectroscopy (WDS) in an electron probe microanalyzer (EPMA) is elaborated. Analysis of a thermal barrier coating (TBC) system formed on a Ni-based single crystal superalloy is presented as an example to illustrate the analysis of samples consisting of a large number of major and minor elements. The analysis was performed by known standards and measured peak-to-background intensity ratios. The procedure for using separate set of acquisition conditions for major and minor element analysis is explained and its importance is stressed.

Ul-Hamid, Anwar [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia)]. E-mail: anwar@kfupm.edu.sa; Tawancy, Hani M. [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia); Mohammed, Abdul-Rashid I. [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia); Al-Jaroudi, Said S. [Saudi Aramco, P.O. Box 65, Tanajib 31311 (Saudi Arabia); Abbas, Nureddin M. [Research Institute, King Fahd University of Petroleum and Minerals, P.O. Box 1073, Dhahran 31261 (Saudi Arabia)

2006-04-15

188

Phase retrieval microscopy for quantitative phase-contrast imaging  

NASA Astrophysics Data System (ADS)

We present an approach for quantitative phase contrast imaging and optical metrology. This technique uses a CCD for in-line hologram recording and the phase retrieval algorithm for hologram reconstruction. The obtained phase distribution is equal, module 2[pi], to the phase distribution of the surface of the object. An application to surface profilometry is presented and good measurement result has been achieved.

Zhang, Y. A. N.; Pedrini, Giancarlo; Osten, Wolfgang; Tiziani, Hans J.

189

Phase retrieval microscopy for quantitative phase-contrast imaging  

Microsoft Academic Search

We present an approach for quantitative phase contrast imaging and optical metrology. This technique uses a CCD for in-line hologram recording and the phase retrieval algorithm for hologram reconstruction. The obtained phase distribution is equal, module 2[pi], to the phase distribution of the surface of the object. An application to surface profilometry is presented and good measurement result has been

Y. A. N. Zhang; Giancarlo Pedrini; Wolfgang Osten; Hans J. Tiziani

2004-01-01

190

Quantitative microscopy and systems biology: seeing the whole picture  

Microsoft Academic Search

Understanding cellular function requires studying the spatially resolved dynamics of protein networks. From the isolated proteins\\u000a we can only learn about their individual properties, but by investigating their behavior in their natural environment, the\\u000a cell, we obtain information about the overall response properties of the network module in which they operate. Fluorescence\\u000a microscopy methods provide currently the only tools to

Peter J. Verveer; Philippe I. H. Bastiaens

2008-01-01

191

Use of digital micromirror devices in quantitative microscopy  

NASA Astrophysics Data System (ADS)

There are numerous modes of microscopy such as brightfield, darkfield, phase contrast, fluorescence, reflected light, confocal, etc. All of these forms of microscopy deliver illumination light in a controlled fashion to the object to be examined and collect as much light containing the desired information as possible. The majority of these methods use appropriately placed and formed diaphragms (iris, pin hole, annulus, etc.) and lenses to control both the incident angles of the illumination light and its intensity as well as the size and location of the illuminated area in the sample. Usually these diaphragms are a simple iris or annulus and are almost always static. The novel aspect of the system being presented is to replace these simple mechanical diaphragms with digital micro mirror devices (1DMDs made by Texas Instruments) to allow for more precise, flexible control over the transmission behavior of these optical planes. By placing DMDs in the same plane (actual or conjugate) as that of the field iris, illumination aperture iris (condenser diaphragm), objective lens aperture stop, and field stop, one has the ability to rapidly switch between brightfield, darkfield, confocal and reconstruction microscopy. In addition because of the intensity modulating features of DMDs, one can create a uniform illumination distributions in the sample or a non- uniform distribution.

Macaulay, Calum E.; Dlugan, Andrew

1998-04-01

192

Char porosity characterisation by scanning electron microscopy and image analysis  

Microsoft Academic Search

No significant change in either the morphotype composition or the macroporosity (pores>5?m) in the 0–30wt.% char burnout interval were revealed by reflected light microscopy or image analysis. Two high temperature char series from a Tertiary South American coal (C1) and a Permian Gondwana coal (C2) were therefore examined by scanning electron microscopy to provide information on the combustion process up

H. S Sørensen; P Rosenberg; H. I Petersen; L. H Sørensen

2000-01-01

193

A NEW EPOXY EMBEDMENT FOR ELECTRON MICROSCOPY  

PubMed Central

A new epoxy embedding mixture has been developed utilizing Maraglas 655 and Cardolite NC-513 with benzyldimethylamine (BDMA) as a curing agent. This epoxy mixture permits cellular preservation comparable to that obtained with Epon 812, ease of preparation of tissues, a wide range of miscibility, low viscosity, and, most important, ease of sectioning on a Porter-Blum microtome. In contrast to Epon-812-embedded tissues, Maraglas-Cardolite-embedded tissues can be sectioned in large dimensions with ease and consistent results without "chatter." No background granularity is detectable with high magnification study of Maraglas-Cardolite-embedded tissues. This epoxy is readily stained with lead hydroxide and is relatively stable in the electron beam.

Freeman, James A.; Spurlock, Ben O.

1962-01-01

194

First morphological characterization of 'Candidatus Mycoplasma turicensis' using electron microscopy  

PubMed Central

At least three haemotropic mycoplasmas have been recognized in cats: Mycoplasma haemofelis (Mhf), ‘Candidatus Mycoplasma haemominutum’ (CMhm) and ‘Candidatus M. turicensis’ (CMt). The latter was originally identified in a Swiss pet cat with haemolytic anaemia and shown to be prevalent in domestic cats and wild felids worldwide using molecular methods. So far, there has been no confirmatory morphological evidence of the existence of CMt presumably due to low blood loads during infection while CMhm has only been characterized by light microscopy with discrepant results. This study aimed to provide for the first time electron microscopic characteristics of CMt and CMhm and to compare them to Mhf. Blood samples from cats experimentally infected with CMt, CMhm and Mhf were used to determine copy numbers in blood by real-time PCR and for transmission and scanning electron microscopy. High resolution scanning electron microscopy revealed CMt and CMhm to be discoid-shaped organisms of 0.3 ?m in diameter attached to red blood cells (RBCs). In transmission electron microscopy of CMt, an oval organism of about 0.25 ?m with several intracellular electron dense structures was identified close to the surface of a RBC. CMhm and CMt exhibited similar morphology to Mhf but had a smaller diameter. This is the first study to provide morphological evidence of CMt thereby confirming its status as a distinct haemoplasma species, and to present electron microscopic features of CMhm.

Willi, Barbara; Museux, Kristina; Novacco, Marilisa; Schraner, Elisabeth M.; Wild, Peter; Groebel, Katrin; Ziegler, Urs; Wolf-Jackel, Godelind A.; Kessler, Yvonne; Geret, Catrina; Tasker, Severine; Lutz, Hans; Hofmann-Lehmann, Regina

2011-01-01

195

Imaging Hydrated Microbial Extracellular Polymers: Comparative Analysis by Electron Microscopy? †  

PubMed Central

Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigation of microscale associations. Electron microscopy has been used extensively for geomicrobial investigations, and although used bona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a direct comparative analysis of microbial interactions by conventional electron microscopy approaches with imaging at room temperature and a suite of cryogenic electron microscopy methods providing imaging in the close-to-natural hydrated state. In situ, we observed an irreversible transformation of the hydrated bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in their collapse into filamentous structures. Dehydration-induced polymer collapse can lead to inaccurate spatial relationships and hence could subsequently affect conclusions regarding the nature of interactions between microbial extracellular polymers and their environment.

Dohnalkova, Alice C.; Marshall, Matthew J.; Arey, Bruce W.; Williams, Kenneth H.; Buck, Edgar C.; Fredrickson, James K.

2011-01-01

196

Imaging hydrated microbial extracellular polymers: Comparative analysis by electron microscopy  

SciTech Connect

Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigating microscale associations. Electron microscopy has been used extensively for geomicrobial investigations and although used bona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a direct comparative analysis of microbial interactions using conventional electron microscopy approaches of imaging at room temperature and a suite of cryogenic electron microscopy methods providing imaging in the close-to-natural hydrated state. In situ, we observed an irreversible transformation of the hydrated bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in their collapse into filamentous structures. Dehydration-induced polymer collapse can lead to inaccurate spatial relationships and hence could subsequently affect conclusions regarding nature of interactions between microbial extracellular polymers and their environment.

Dohnalkova, A.C.; Marshall, M. J.; Arey, B. W.; Williams, K. H.; Buck, E. C.; Fredrickson, J. K.

2011-01-01

197

Quantitative Phase Imaging in Microscopy Using a Spatial Light Modulator  

Microsoft Academic Search

\\u000a In this chapter, we present a new method capable of recovery of the quantitative phase\\u000a information of microscopic samples. Essentially, a spatial light modulator (SLM)\\u000a and digital image processing are the basics to extract the sample’s phase distribution. The SLM\\u000a produces a set of misfocused images of the input sample at the CCD plane by displaying a set of lenses

Vicente Micó; Javier García; Luis Camacho; Zeev Zalevsky

198

Evaluations of carbon nanotube field emitters for electron microscopy  

NASA Astrophysics Data System (ADS)

Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I- V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability of CNT for electron microscopy. As a result, it is obtained that an emission area of MWNT is smaller than its tip surface area, and the emission area corresponds to a five-membered-ring with 2nd nearest six-membered-rings on the MWNT cap surface. Reduced brightness of MWNT is measured as at least 2.6×109 A/m 2 sr V. It is concluded that even a thick MWNT has enough brightness under a practical e-gun electrode configuration and suitable for electron microscopy.

Nakahara, Hitoshi; Kusano, Yoshikazu; Kono, Takumi; Saito, Yahachi

2009-11-01

199

The application of scanning electron microscopy to fractography  

SciTech Connect

Many failures involve fracture, and determination of the fracture process is a key factor in understanding the failure. This is frequently accomplished by characterizing the topography of the fracture surface. Scanning electron microscopy has a prominent role in fractography due to three features of the scanning electron microscope (SEM): high resolution, great depth of field, and the ability to obtain chemical information via analysis of the X-rays generated by the electrons. A qualitative treatment is presented of the interaction of electrons with a sample and the effect of the SEM operating parameters on image formation, quality, and X-ray analysis. Fractographs are presented to illustrate these features of scanning electron microscopy and to illustrate the limitations and precautions in obtaining fractographs and x-ray analyses. The review is concluded with examples of fracture surface features of metallic, ceramic, and polymeric materials.

Brooks, C.R.; McGill, B.L. (Univ. of Tennessee, Knoxville, TN (United States))

1994-10-01

200

Laboratory design for high-performance electron microscopy  

SciTech Connect

Proliferation of electron microscopes with field emission guns, imaging filters and hardware spherical aberration correctors (giving higher spatial and energy resolution) has resulted in the need to construct special laboratories. As resolutions improve, transmission electron microscopes (TEMs) and scanning transmission electron microscopes (STEMs) become more sensitive to ambient conditions. State-of-the-art electron microscopes require state-of-the-art environments, and this means careful design and implementation of microscope sites, from the microscope room to the building that surrounds it. Laboratories have been constructed to house high-sensitive instruments with resolutions ranging down to sub-Angstrom levels; we present the various design philosophies used for some of these laboratories and our experiences with them. Four facilities are described: the National Center for Electron Microscopy OAM Laboratory at LBNL; the FEGTEM Facility at the University of Sheffield; the Center for Integrative Molecular Biosciences at TSRI; and the Advanced Microscopy Laboratory at ORNL.

O'Keefe, Michael A.; Turner, John H.; Hetherington, Crispin J.D.; Cullis, A.G.; Carragher, Bridget; Jenkins, Ron; Milgrim, Julie; Milligan,Ronald A.; Potter, Clinton S.; Allard, Lawrence F.; Blom, Douglas A.; Degenhardt, Lynn; Sides, William H.

2004-04-23

201

Electron Microscopy and Electron Diffraction of Frozen, Hydrated Biological Specimens.  

National Technical Information Service (NTIS)

A method has been developed for the study in the electron microscope of frozen, unstained, hydrated biological specimens. Methodology is described for the preparation of frozen, sandwiched specimens and for their introduction into the electron microscope....

K. A. Taylor

1975-01-01

202

Low Temperature Electron Microscopy and Electron Diffraction of the Purple Membrane of Halobacterium Halobium.  

National Technical Information Service (NTIS)

The structure of the purple membrane of Halobacterium halobium was studied by high resolution electron microscopy and electron diffraction, primarily at low temperature. The handedness of the purple membrane diffraction pattern with respect to the cell me...

S. B. Hayward

1978-01-01

203

Digital holographic microscopy for quantitative cell dynamic evaluation during laser microsurgery  

PubMed Central

Digital holographic microscopy allows determination of dynamic changes in the optical thickness profile of a transparent object with subwavelength accuracy. Here, we report a quantitative phase laser microsurgery system for evaluation of cellular/ sub-cellular dynamic changes during laser micro-dissection. The proposed method takes advantage of the precise optical manipulation by the laser microbeam and quantitative phase imaging by digital holographic microscopy with high spatial and temporal resolution. This system will permit quantitative evaluation of the damage and/or the repair of the cell or cell organelles in real time.

Yu, Lingfeng; Mohanty, Samarendra; Zhang, Jun; Genc, Suzanne; Kim, Myung K.; Berns, Michael W.; Chen, Zhongping

2010-01-01

204

Structured illumination quantitative phase microscopy for enhanced resolution amplitude and phase imaging  

PubMed Central

Structured illumination microscopy (SIM) is an established microscopy technique typically used to image samples at resolutions beyond the diffraction limit. Until now, however, achieving sub-diffraction resolution has predominantly been limited to intensity-based imaging modalities. Here, we introduce an analogue to conventional SIM that allows sub-diffraction resolution, quantitative phase-contrast imaging of optically transparent objects. We demonstrate sub-diffraction resolution amplitude and quantitative-phase imaging of phantom targets and enhanced resolution quantitative-phase imaging of cells. We report a phase accuracy to within 5% and phase noise of 0.06 rad.

Chowdhury, Shwetadwip; Izatt, Joseph

2013-01-01

205

Transmission Electron Microscopy Characterization of Helium Bubbles in Aged Plutonium  

SciTech Connect

The self-irradiation damage generated by alpha decay of plutonium results in the formation of lattice defects, helium, and uranium atoms. Over time, microstructural evolution resulting from the self-irradiation may influence the physical and mechanical properties of the material. In order to assess microstructural changes, we have developed and applied procedures for the specimen preparation, handling, and transmission electron microscopy characterization of Pu alloys. These transmission electron microscopy investigations of Pu-Ga alloys ranging in age up to 42-years old reveal the presence of nanometer-sized helium bubbles. The number density of bubbles and the average size have been determined for eight different aged materials.

Schwartz, A J; Wall, M A; Zocco, T G; Blobaum, K M

2004-11-02

206

Semi-automated reconstruction of neural circuits using electron microscopy.  

PubMed

Reconstructing neuronal circuits at the level of synapses is a central problem in neuroscience, and the focus of the nascent field of connectomics. Previously used to reconstruct the C. elegans wiring diagram, serial-section transmission electron microscopy (ssTEM) is a proven technique for the task. However, to reconstruct more complex circuits, ssTEM will require the automation of image processing. We review progress in the processing of electron microscopy images and, in particular, a semi-automated reconstruction pipeline deployed at Janelia Farm. Drosophila circuits underlying identified behaviors are being reconstructed in the pipeline with the goal of generating a complete Drosophila connectome. PMID:20833533

Chklovskii, Dmitri B; Vitaladevuni, Shiv; Scheffer, Louis K

2010-09-15

207

Strain mapping technique for performance improvement of strained MOSFETs with scanning transmission electron microscopy  

Microsoft Academic Search

A new approach of strain mapping is proposed with scanning transmission electron microscopy and applied to strained MOSFETs for the first time. This technique is extended to quantitative measurement with sub-nano meter spatial resolution combining with nano-beam diffraction. As a result, two-dimensional strain mapping with sub-nano meter spatial resolution is obtained and actual strain at inversion layer was determined using

N. Nakanishi; S. Kudo; M. Kawakami; T. Hayashi; H. Oda; T. Uchida; Y. Miyagawa; K. Asai; K. Ohnishi; N. Hattori; Y. Hirose; T. Koyama; K. Asayama; E. Murakami

2008-01-01

208

Quantitative flaw characterization with scanning laser acoustic microscopy  

SciTech Connect

Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw. 15 references.

Generazio, E.R.; Roth, D.J.

1986-06-01

209

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

PubMed

The aim of this work was to assess the changes in the microstructure of hot-deformed specimens made of alloys containing 46-50 at.% Al, 2 at.% Cr and 2 at.% Nb (and alloying additions such as carbon and boron) with the aid of scanning electron microscopy and transmission electron microscopy techniques. After homogenization and heat treatment performed in order to make diverse lamellae thickness, the specimens were compressed at 1000 degrees C. Transmission electron microscopy examinations of specimens after the compression test revealed the presence of heavily deformed areas with a high density of dislocation. Deformation twins were also observed. Dynamically recrystallized grains were revealed. For alloys no. 2 and no. 3, the recovery and recrystallization processes were more extensive than for alloy no. 1. PMID:17059556

Chrapo?ski, J; Rodak, K

2006-09-01

210

Imaging doped silicon test structures using low energy electron microscopy.  

SciTech Connect

This document is the final SAND Report for the LDRD Project 105877 - 'Novel Diagnostic for Advanced Measurements of Semiconductor Devices Exposed to Adverse Environments' - funded through the Nanoscience to Microsystems investment area. Along with the continuous decrease in the feature size of semiconductor device structures comes a growing need for inspection tools with high spatial resolution and high sample throughput. Ideally, such tools should be able to characterize both the surface morphology and local conductivity associated with the structures. The imaging capabilities and wide availability of scanning electron microscopes (SEMs) make them an obvious choice for imaging device structures. Dopant contrast from pn junctions using secondary electrons in the SEM was first reported in 1967 and more recently starting in the mid-1990s. However, the serial acquisition process associated with scanning techniques places limits on the sample throughput. Significantly improved throughput is possible with the use of a parallel imaging scheme such as that found in photoelectron emission microscopy (PEEM) and low energy electron microscopy (LEEM). The application of PEEM and LEEM to device structures relies on contrast mechanisms that distinguish differences in dopant type and concentration. Interestingly, one of the first applications of PEEM was a study of the doping of semiconductors, which showed that the PEEM contrast was very sensitive to the doping level and that dopant concentrations as low as 10{sup 16} cm{sup -3} could be detected. More recent PEEM investigations of Schottky contacts were reported in the late 1990s by Giesen et al., followed by a series of papers in the early 2000s addressing doping contrast in PEEM by Ballarotto and co-workers and Frank and co-workers. In contrast to PEEM, comparatively little has been done to identify contrast mechanisms and assess the capabilities of LEEM for imaging semiconductor device strictures. The one exception is the work of Mankos et al., who evaluated the impact of high-throughput requirements on the LEEM designs and demonstrated new applications of imaging modes with a tilted electron beam. To assess its potential as a semiconductor device imaging tool and to identify contrast mechanisms, we used LEEM to investigate doped Si test structures. In section 2, Imaging Oxide-Covered Doped Si Structures Using LEEM, we show that the LEEM technique is able to provide reasonably high contrast images across lateral pn junctions. The observed contrast is attributed to a work function difference ({Delta}{phi}) between the p- and n-type regions. However, because the doped regions were buried under a thermal oxide ({approx}3.5 nm thick), e-beam charging during imaging prevented quantitative measurements of {Delta}{phi}. As part of this project, we also investigated a series of similar test structures in which the thermal oxide was removed by a chemical etch. With the oxide removed, we obtained intensity-versus-voltage (I-V) curves through the transition from mirror to LEEM mode and determined the relative positions of the vacuum cutoffs for the differently doped regions. Although the details are not discussed in this report, the relative position in voltage of the vacuum cutoffs are a direct measure of the work function difference ({Delta}{phi}) between the p- and n-doped regions.

Nakakura, Craig Yoshimi; Anderson, Meredith Lynn; Kellogg, Gary Lee

2010-01-01

211

Photoemission electron microscopy beamline at the Synchrotron Light Research Institute  

NASA Astrophysics Data System (ADS)

Photoemission electron microscopy end station is installed at Beamline 3.2b of Siam Photon Laboratory of the Synchrotron Light Research Institute in Thailand. The system has been tested for sample imaging using synchrotron, a UV lamp and an electron gun as sources with successful results. Multi-disciplinary research at the PEEM end station is reported in this paper. Arc discharge problem which have been found during the experiments is also discussed.

Euaruksakul, C.; Jearanaikoon, N.; Bussayaporn, W.; Kamonsutthipaijit, N.; Photongkam, P.; Tunmee, S.; Songsiriritthigul, P.

2013-03-01

212

Photoemission electron microscopy of individual single-walled carbon nanotubes  

Microsoft Academic Search

Individual suspended single-walled carbon nanotubes were observed by means of C 1s and secondary electron photoemission electron microscopy. No band bending was observed in the images, suggesting that the depletion width near the catalytic Fe\\/nanotube or substrate Si\\/nanotube contact is comparable to the spatial resolution of 40nm or less. Work function differences between the nanotubes were clearly observed in secondary

Satoru Suzuki; Yoshio Watanabe; Yoshikazu Homma; Shin-ya Fukuba; Andrea Locatelli; Stefan Heun

2005-01-01

213

Diffusion of chloroaluminum phthalocyanine on MoS2 surface detected by photoemission electron microscopy and metastable electron emission microscopy  

NASA Astrophysics Data System (ADS)

Diffusion of a large organic semiconductor molecule, chloroaluminum phthalocyanine (ClAlPc), on a cleaved MoS2 surface was detected using photoemission electron microscopy (PEEM) and metastable electron emission microscopy (MEEM). The PEEM and MEEM images showed that a micropattern of ClAlPc ultrathin film prepared on the MoS2 surface by vacuum deposition shrinks with time and finally disappears even at room temperature at which the molecules do not evaporate. The results indicate that control of molecular diffusion is necessary for the preparation of stable micro or nanostructure of organic thin films.

Yasufuku, H.; Ibe, T.; Okumura, M.; Kera, S.; Okudaira, K. K.; Harada, Y.; Ueno, N.

2001-07-01

214

Scanning electron microscopy of Setaria cervi adult male worms.  

PubMed

Scanning electron microscopy studies of adult Setaria cervi male worms showed the presence of horn-like lateral appendages and characteristic striated bands on the ventral side of the tail. All other features were indistinguishable from other members of the genus Setaria. PMID:2040560

Almeida, A J; Deobhankar, K P; Bhopale, M K; Zaman, V; Renapurkar, D M

1991-02-01

215

Subliming Ice Surfaces: Freeze-Etch Electron Microscopy  

Microsoft Academic Search

Vacuum sublimation of oriented single crystals of ice at temperatures from -110 to -60 degrees Celsius was studied by electron microscopy with the freeze-etch technique. Sublimation etches the ice surface to produce pits and asperities and above -85 degrees Celsius causes extreme surface roughening. The etch pits are ascribed to surface dislocations, and the extreme roughening is ascribed to the

J. Gordon Davy; Daniel Branton

1970-01-01

216

Lorentz electron microscopy of rare-earth permanent magnets  

Microsoft Academic Search

Purpose of this work is to determine the relationship of the microstructure with the magnetic domain structure to clarify the origin of the high-coercive fields in these permanent magnet materials Sm (Co, Fe, Cu, Zr)\\/sub x\\/. Lorentz electron microscopy has been used to image the domain walls and study their interactions with crystalline defects.

G. C. Hadjipanayis; L. L. Horton

1983-01-01

217

Electron microscopy and diffraction of aluminium oxide whiskers  

Microsoft Academic Search

Whiskers of ?-Al2O3 have been grown by the condensation and oxidation of aluminium on an alumina substrate, and examined by transmission electron microscopy and diffraction. Unbroken whiskers invariably terminate in a small globule of aluminium and have a ‘drumstick’ form. The most perfect whiskers are ribbons with their principal surfaces parallel to the (0001) planes; the majority of these have

D. J. Barber

1964-01-01

218

Detection of viruses in avian faeces by direct electron microscopy  

Microsoft Academic Search

A total of 151 specimens of turkey and chicken faeces and intestinal contents were examined for the presence of viruses by electron microscopy. Viruses were detected in 48 of these specimens (32%). The most frequently observed viruses were rotaviruses and enterovirus?like particles. Rotavirus infection was associated with outbreaks of diarrhoea in turkeys, but symptomless rotavirus infection was seen in broiler

M. S. McNulty; W. L. Curran; D. Todd; J. B. McFerran

1979-01-01

219

Electron Microscopy and Analysis Group Conference 2011 (EMAG 2011)  

Microsoft Academic Search

The biennial EMAG conference has established a strong reputation as a key event for the national and international electron microscopy community. In 2011 the meeting was held at The University of Birmingham, and I must first take this opportunity of thanking Birmingham for hosting the conference and for the excellent support we received from the local organisers. As a committee,

Guenter Moebus; Thomas Walther; Rik Brydson; Dogan Ozkaya; Ian MacLaren; Steve Donnelly; Pete Nellist; Ziyou Li; Richard Baker; YuLung Chiu

2012-01-01

220

Collaboration at the Nanoscale: Exploring Viral Genetics with Electron Microscopy  

ERIC Educational Resources Information Center

|The Maine Science Corps is a project sponsored by the National Science Foundation's (NSF) Graduate Teaching Fellows in K-12 Education (GK-12 ) program. Through this program, the University of Southern Maine's (USM) virology and transmission electron microscopy (TEM) research group provides high school teachers and students in rural areas with…

Duboise, S. Monroe; Moulton, Karen D.; Jamison, Jennifer L.

2009-01-01

221

Quantifying Nanoscale Order in Amorphous Materials via Fluctuation Electron Microscopy  

ERIC Educational Resources Information Center

|Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function…

Bogle, Stephanie Nicole

2009-01-01

222

Electron microscopy of oligodendroglia in severe mental illness  

Microsoft Academic Search

Qualitative electron microscopy was performed to verify whether brain pathology in schizophrenia and bipolar disorder is associated with alterations of oligodendroglial cells and myelinated fibers. Ultrastructural signs of apoptosis and necrosis of oligodendroglial cells were found in the prefrontal area 10 and the caudate nucleus in both schizophrenia and bipolar disorder. Damage of myelin sheath lamellae, with the formation of

Natalya Uranova; Diana Orlovskaya; Olga Vikhreva; Ivetta Zimina; Natalya Kolomeets; Victor Vostrikov; Valentina Rachmanova

2001-01-01

223

Metals on BN Studied by High Resolution Transmission Electron Microscopy  

NASA Astrophysics Data System (ADS)

Metal impurities, gold and nickel, have been deliberately introduced into boron-nitride (BN) sheets. The structural and topographic properties of doped BN have been studied by aberration corrected scanning transmission electron microscopy (STEM). Analysis revealed that metal atoms cluster preferentially in/on contaminated areas. The metal coverage on BN is almost the same for the same evaporated amount of 1 Å.

Bangert, U.; Zan, R.; Ramasse, Q.; Jalil, Rashid; Riaz, Ibstam; Novoselov, K. S.

2012-07-01

224

Transmission electron microscopy of polymer blends and block copolymers  

Microsoft Academic Search

Transmission electron microscopy (TEM) of soft matter is a field that warrants further investigation. Developments in sample preparation, imaging and spectroscopic techniques could lead to novel experiments that may further our understanding of the structure and the role structure plays in the functionality of various organic materials. Unlike most hard materials, TEM of organic molecules is limited by the amount

Enrique Daniel Gomez

2007-01-01

225

Imaging of plant microtubules with high resolution scanning electron microscopy  

Microsoft Academic Search

Summary High resolution scanning electron microscopy was used to obtain images of cortical microtubules and associated structures in onion root tips. Specimens were prepared using a modified quick-freeze deep-etch technique utilising cytosolic extraction with saponin and conductive staining with osmium.

P. A. Vesk; D. G. Rayns; M. Vesk

1994-01-01

226

Transmission Electron Microscopy (TEM) investigations of ancient Egyptian cosmetic powders  

Microsoft Academic Search

The processing technologies available during the time of ancient Egypt are of present concern to the field of Archaeology and Egyptology. Materials characterization is the best tool for establishing the processing history of archaeological objects. In this study, transmission electron microscopy (TEM) is used, in addition to other techniques, for phase identification and study of the microstructure and characteristic defect

C. Deeb; P. Walter; J. Castaing; P. Penhoud; P. Veyssière

2004-01-01

227

DICHOTOMOUS SAMPLERS MODIFIED FOR USE WITH ELECTRON MICROSCOPY  

EPA Science Inventory

Large sulfate artifacts up to 2 um in diameter were observed by scanning electron microscopy for the fine particle fraction collected in dichotomous samplers. he artifacts were attributed to small liquid particles that piled up on the filter, coalesced, and later dried as larger ...

228

STAINING OF TISSUE SECTIONS FOR ELECTRON MICROSCOPY WITH HEAVY METALS  

Microsoft Academic Search

ABS>Heavy metals may be incorporated from solution into tissue sections ; for electron microscopy. The resulting increase in density of the tissue ; provides greatly enhanced contrast with minimal distortion. Relative densities ; of various structures are found to depend on the heavy metal ions present and on ; the conditions of staining. Certain hitherto unobserved details are revealed and

M. L. Watson

1958-01-01

229

Study of Aluminium Brazes Using Hot Stage Scanning Electron Microscopy.  

National Technical Information Service (NTIS)

Hot stage scanning electron microscopy was used to study the behavior of aluminum vacuum brazes. The techniques was employed to observe the surface changes which a braze experiences on heating and to observe the formation of bonds between a braze and a wo...

B. Mcgurran M. G. Nicholas

1983-01-01

230

Ultradeep, ultramafic mantle xenoliths: transmission electron microscopy preliminary results  

Microsoft Academic Search

The defect microstructure of ultradeep garnets from the Jagersfontein kimberlite pipe (South Africa) was investigated by transmission electron microscopy. These crystals exhibit a high density of dislocations, most of which form well-organized and regularly spaced subgrain boundaries. Free dislocations are also detected; most of them have a Burgers vector 1\\/2 (shortest lattice repeat), but a few Burgers vectors are also

N. Doukhan; V. Sautter; J. C. Doukhan

1994-01-01

231

Pathogenesis of Monilethrix: Computer Stereography and Electron Microscopy  

Microsoft Academic Search

The plucked hairs and biopsied hair follicles of the scalp were obtained from a female patient with monilethrix. By scanning electron microscopy, the plucked hairs showed a typical moniliform feature composed of alternated nodes and inter- nodes. By computer stereography, reconstructed three-dimensional models of in vivo hair structures showed that the diameter of hair shaft was partially reduced in the

Masaaki Ito; Ken Hashimoto; Kaoru Katsuumi; Yoshio Sato

1990-01-01

232

Karnovsky-osmium as a primary fixative for electron microscopy  

NASA Astrophysics Data System (ADS)

A combined Karnovsky-osmium tetroxide primary fixative is proposed for transmission electron microscopy. This fixative, hypothetically, seems to overcome the drawbacks of sequential fixation techniques. Evaluation of this combined fixative reveals very acceptable fixation of hepatocytes, lymphocytes, and fibroblasts, as well as various organelles within these cells.

Buchanan, G. M.

1983-09-01

233

Imaging Hydrated Microbial Extracellular Polymers: Comparative Analysis by Electron Microscopy  

Microsoft Academic Search

Microbe-mineral and -metal interactions represent a major intersection between the biosphere and geosphere but require high-resolution imaging and analytical tools for investigating microscale associations. Electron microscopy has been used extensively for geomicrobial investigations and although used bona fide, the traditional methods of sample preparation do not preserve the native morphology of microbiological components, especially extracellular polymers. Herein, we present a

Alice Dohnalkova; Matthew J. Marshall; Bruce W. Arey; Kenneth H. Williams; Edgar C. Buck; Jim K. Fredrickson

2011-01-01

234

An Introduction to Energy-Filtered Transmission Electron Microscopy  

Microsoft Academic Search

This article introduces the topic of energy-filtered transmission electron microscopy (EFTEM). It reviews the technique combining theory with a number of applications from materials science to highlight the progress made in the subject. Examples of EFTEM of catalysts are also reviewed with a discussion of how the technique could be used to study many more catalyst structures in the future.

P. J. Thomas; P. A. Midgley

2002-01-01

235

Transmission electron microscopy investigation of auto catalyst and cobalt germanide  

Microsoft Academic Search

The modern ceria-zirconia based catalysts are used in automobiles to reduce exhaust pollutants. Cobalt germanides have potential applications as electrical contacts in the future Ge-based semiconductor devices. In this thesis, transmission electron microscopy (TEM) techniques were used to study the atomic scale interactions between metallic nanostructures and crystalline substrates in the two material systems mentioned above. The model catalyst samples

Haiping Sun

2005-01-01

236

Depth profiling of integrated circuits with thermal wave electron microscopy  

Microsoft Academic Search

Nondestructive depth profiling of integrated circuits was performed with thermal wave electron microscopy at a 640 kHz modulation frequency. Images were obtained at both a shallow penetration (near surface) and a deep penetration (subsurface) phase setting. It is the deep penetration image that provides new data and the capability for the nondestructive detection of subsurface flaws in integrated circuits. It

A. Rosencwaig

1980-01-01

237

LOW-TEMPERATURE SCANNING ELECTRON MICROSCOPY OF ARTIFICIAL SNOW  

Technology Transfer Automated Retrieval System (TEKTRAN)

Low temperature scanning electron microscopy (LTSEM) has been used to observe and characterize fresh and metamorphosed naturally formed snow crystals1. These crystals form in the atmosphere by a process known as vapor deposition, in which molecules of water vapor (gas) bind to form a crystal (solid...

238

Asbestos fibres in bronchoalveolar lavage fluid from asbestos workers: examination by electron microscopy.  

PubMed Central

The uncoated and coated fibre load in bronchoalveolar lavage (BAL) fluid was assessed using light microscopy, scanning electron microscopy, and x ray microanalysis in 15 subjects with previous, unprotected exposure to asbestos, including three with clinical and radiological evidence of asbestosis, and in 13 urban dwelling control subjects with no known occupational exposure to asbestos. The mean ferruginous body count per ml BAL fluid in asbestos exposed subjects as determined by light microscopy was 52 (range 0-333). No ferruginous bodies were detected in control subjects. The mean fibre count per ml BAL fluid in asbestos exposed subjects as determined by electron microscopy was 793 (133-3700), significantly greater than 239 (44-544) in controls (p less than 0.05). Electron microscopic counts correlated with duration of previous exposure to asbestos (r = 0.47, p less than 0.05) and with percentage neutrophil counts (r = 0.53, p less than 0.025). There was no relation between electron microscopic fibre counts and light microscopic ferruginous body counts. In 11 asbestos exposed cases x ray microanalysis confirmed the presence of asbestos and in six the asbestos fibre type was clearly identified. Of five subjects showing no asbestos bodies by light microscopy, all showed fibres by electron microscopy, and in three cases the presence of asbestos was confirmed by microanalysis. Among control subjects, fibres were either large organic fibres or smaller particles which microanalysis showed were not asbestos. In only one control case were a few fibres identified which were confirmed as asbestos fibres on microanalysis. Electron microscopic examination of BAL fluid may confirm past exposure to asbestos and probably gives a crude quantitative estimate of asbestos load. Images

Gellert, A R; Kitajewska, J Y; Uthayakumar, S; Kirkham, J B; Rudd, R M

1986-01-01

239

Asbestos fibres in bronchoalveolar lavage fluid from asbestos workers: examination by electron microscopy.  

PubMed

The uncoated and coated fibre load in bronchoalveolar lavage (BAL) fluid was assessed using light microscopy, scanning electron microscopy, and x ray microanalysis in 15 subjects with previous, unprotected exposure to asbestos, including three with clinical and radiological evidence of asbestosis, and in 13 urban dwelling control subjects with no known occupational exposure to asbestos. The mean ferruginous body count per ml BAL fluid in asbestos exposed subjects as determined by light microscopy was 52 (range 0-333). No ferruginous bodies were detected in control subjects. The mean fibre count per ml BAL fluid in asbestos exposed subjects as determined by electron microscopy was 793 (133-3700), significantly greater than 239 (44-544) in controls (p less than 0.05). Electron microscopic counts correlated with duration of previous exposure to asbestos (r = 0.47, p less than 0.05) and with percentage neutrophil counts (r = 0.53, p less than 0.025). There was no relation between electron microscopic fibre counts and light microscopic ferruginous body counts. In 11 asbestos exposed cases x ray microanalysis confirmed the presence of asbestos and in six the asbestos fibre type was clearly identified. Of five subjects showing no asbestos bodies by light microscopy, all showed fibres by electron microscopy, and in three cases the presence of asbestos was confirmed by microanalysis. Among control subjects, fibres were either large organic fibres or smaller particles which microanalysis showed were not asbestos. In only one control case were a few fibres identified which were confirmed as asbestos fibres on microanalysis. Electron microscopic examination of BAL fluid may confirm past exposure to asbestos and probably gives a crude quantitative estimate of asbestos load. PMID:3947579

Gellert, A R; Kitajewska, J Y; Uthayakumar, S; Kirkham, J B; Rudd, R M

1986-03-01

240

Critical evaluation of quantitative colocalization analysis in confocal fluorescence microscopy.  

PubMed

Spatial colocalization of fluorescently labeled proteins can reveal valuable information about proteinprotein interactions. Compared to qualitative visual interpretation of dual color images, quantitative colocalization analysis (QCA) provides more objective evaluations to the degree of colocalization. However, the finite resolution power of microscopes and the spatial patterns of intracellular structures may compromise the reliability of many classical QCA methods. In this paper, we discuss the strength and weakness of some mostly used QCA methods. By studying their applications on computer-simulated images and biological images, we show that classical pixel intensity based QCA methods are often vulnerable to coincidental overlapping among resolution elements (resel) distributions and thus not suitable to images with high molecular density or with low resolution. Also, many QCA methods can mistakenly regard long range correlation as colocalization due to protein localization in intracellular structures. The newly developed protein-protein index (PPI) approach is able to reduce the influence from resel overlapping and spatial intracellular pattern compared to previous methods, significantly improving the reliability of QCA. PMID:22392274

Wu, Yong; Zinchuk, Vadim; Grossenbacher-Zinchuk, Olga; Stefani, Enrico

2012-03-06

241

Quantitative phase imaging of electron waves using selected-area diffraction  

NASA Astrophysics Data System (ADS)

A method for quantitative phase imaging of electron waves was developed based on diffractive imaging. Phase images over field of views of more than 100 nm were reconstructed from pairs of a selected-area diffraction pattern and a transmission electron microscopy image. The illumination wave field was reconstructed uniformly with a phase fluctuation of less than 0.1 rad and a spatial resolution of 2-3 nm. The phase image for wedge-shaped silicon was converted to a thickness map, which agreed quantitatively with electron energy-loss spectroscopy. The present method is also valid for arbitrary-shaped samples even if dynamical diffraction effects are significant.

Yamasaki, J.; Ohta, K.; Morishita, S.; Tanaka, N.

2012-12-01

242

High-resolution low-dose scanning transmission electron microscopy  

PubMed Central

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

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

2010-01-01

243

Enhanced imaging in low dose electron microscopy using electron counting.  

PubMed

We compare the direct electron imaging performance at 120keV of a monolithic active pixel sensor (MAPS) operated in a conventional integrating mode with the performance obtained when operated in a single event counting mode. For the combination of sensor and incident electron energy used here, we propose a heuristic approach with which to process the single event images in which each event is renormalised to have an integrated weight of unity. Using this approach we find enhancements in the Nyquist frequency modulation transfer function (MTF) and detective quantum efficiency (DQE) over the corresponding integrating mode values by factors of 8 and 3, respectively. PMID:19647366

McMullan, G; Clark, A T; Turchetta, R; Faruqi, A R

2009-07-15

244

Enhanced imaging in low dose electron microscopy using electron counting  

PubMed Central

We compare the direct electron imaging performance at 120 keV of a monolithic active pixel sensor (MAPS) operated in a conventional integrating mode with the performance obtained when operated in a single event counting mode. For the combination of sensor and incident electron energy used here, we propose a heuristic approach with which to process the single event images in which each event is renormalised to have an integrated weight of unity. Using this approach we find enhancements in the Nyquist frequency modulation transfer function (MTF) and detective quantum efficiency (DQE) over the corresponding integrating mode values by factors of 8 and 3, respectively.

McMullan, G.; Clark, A.T.; Turchetta, R.; Faruqi, A.R.

2009-01-01

245

The intermediate size direct detection detector for electron microscopy  

NASA Astrophysics Data System (ADS)

In a longstanding effort to overcome limits of film and the charge coupled device (CCD) systems in electron microscopy, we have developed a radiation-tolerant system that can withstand direct electron bombardment. A prototype Direct Detection Device (DDD) detector based on an Active Pixel Sensor (APS) has delivered unprecedented performance with an excellent signal-to-noise ratio (approximately 5/1 for a single incident electron in the range of 200-400 keV) and a very high spatial resolution. This intermediate size prototype features a 512×550 pixel format of 5?m pitch. The detector response to uniform beam illumination and to single electron hits is reported. Radiation tolerance with high-energy electron exposure is also impressive, especially with cooling to -15 °C. Stable performance has been demonstrated, even after a total dose of 3.3×106 electrons/pixel. The characteristics of this new detector have exciting implications for transmission electron microscopy, especially for cryo-EM as applied to biological macromolecules.

Jin, Liang; Milazzo, Anna-Clare; Kleinfelder, Stuart; Li, Shengdong; Leblanc, Philippe; Duttweiler, Fred; Bouwer, James C.; Peltier, Steve T.; Ellisman, Mark; Xuong, Nguyen-Huu

2007-03-01

246

Correlated Light and Electron Microscopy/Electron Tomography of Mitochondria In Situ  

PubMed Central

Three-dimensional light microscopy and three-dimensional electron microscopy (electron tomography) separately provide very powerful tools to study cellular structure and physiology, including the structure and physiology of mitochondria. Fluorescence microscopy allows one to study processes in live cells with specific labels and stains that follow the movement of labeled proteins and changes within cellular compartments but does not have sufficient resolution to define the ultrastructure of intracellular organelles such as mitochondria. Electron microscopy and electron tomography provide the highest resolution currently available to study mitochondrial ultrastructure but cannot follow processes in living cells. We describe the combination of these two techniques in which fluorescence confocal microscopy is used to study structural and physiologic changes in mitochondria within apoptotic HeLa cells to define the apoptotic timeframe. Cells can then be selected at various stages of the apoptotic timeframe for examination at higher resolution by electron microscopy and electron tomography. This is a form of “virtual” 4-dimensional electron microscopy that has revealed interesting structural changes in the mitochondria of HeLa cells during apoptosis. The same techniques can be applied, with modification, to study other dynamic processes within cells in other experimental contexts.

Perkins, Guy A.; Sun, Mei G.; Frey, Terrence G.

2009-01-01

247

Detective quantum efficiency of electron area detectors in electron microscopy.  

PubMed

Recent progress in detector design has created the need for a careful side-by-side comparison of the modulation transfer function (MTF) and resolution-dependent detective quantum efficiency (DQE) of existing electron detectors with those of detectors based on new technology. We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the Medipix2 hybrid pixel detector, and an experimental direct electron monolithic active pixel sensor (MAPS) detector. Film and CCD performance was measured at 120 and 300 keV, while results are presented for the Medipix2 at 120 keV and for the MAPS detector at 300 keV. In the case of film, the effects of electron backscattering from both the holder and the plastic support have been investigated. We also show that part of the response of the emulsion in film comes from light generated in the plastic support. Computer simulations of film and the MAPS detector have been carried out and show good agreement with experiment. The agreement enables us to conclude that the DQE of a backthinned direct electron MAPS detector is likely to be equal to, or better than, that of film at 300 keV. PMID:19497671

McMullan, G; Chen, S; Henderson, R; Faruqi, A R

2009-05-07

248

Detective quantum efficiency of electron area detectors in electron microscopy  

PubMed Central

Recent progress in detector design has created the need for a careful side-by-side comparison of the modulation transfer function (MTF) and resolution-dependent detective quantum efficiency (DQE) of existing electron detectors with those of detectors based on new technology. We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the Medipix2 hybrid pixel detector, and an experimental direct electron monolithic active pixel sensor (MAPS) detector. Film and CCD performance was measured at 120 and 300 keV, while results are presented for the Medipix2 at 120 keV and for the MAPS detector at 300 keV. In the case of film, the effects of electron backscattering from both the holder and the plastic support have been investigated. We also show that part of the response of the emulsion in film comes from light generated in the plastic support. Computer simulations of film and the MAPS detector have been carried out and show good agreement with experiment. The agreement enables us to conclude that the DQE of a backthinned direct electron MAPS detector is likely to be equal to, or better than, that of film at 300 keV.

McMullan, G.; Chen, S.; Henderson, R.; Faruqi, A.R.

2009-01-01

249

Studying atomic structures by aberration-corrected transmission electron microscopy.  

PubMed

Seventy-five years after its invention, transmission electron microscopy has taken a great step forward with the introduction of aberration-corrected electron optics. An entirely new generation of instruments enables studies in condensed-matter physics and materials science to be performed at atomic-scale resolution. These new possibilities are meeting the growing demand of nanosciences and nanotechnology for the atomic-scale characterization of materials, nanosynthesized products and devices, and the validation of expected functions. Equipped with electron-energy filters and electron-energy-loss spectrometers, the new instruments allow studies not only of structure but also of elemental composition and chemical bonding. The energy resolution is about 100 milli-electron volts, and the accuracy of spatial measurements has reached a few picometers. However, understanding the results is generally not straightforward and only possible with extensive quantum-mechanical computer calculations. PMID:18653874

Urban, Knut W

2008-07-25

250

Human enamel structure studied by high resolution electron microscopy  

SciTech Connect

Human enamel structural features are characterized by high resolution electron microscopy. The human enamel consists of polycrystals with a structure similar to Ca10(PO4)6(OH)2. This article describes the structural features of human enamel crystal at atomic and nanometer level. Besides the structural description, a great number of high resolution images are included. Research into the carious process in human enamel is very important for human beings. This article firstly describes the initiation of caries in enamel crystal at atomic and unit-cell level and secondly describes the further steps of caries with structural and chemical demineralization. The demineralization in fact, is the origin of caries in human enamel. The remineralization of carious areas in human enamel has drawn more and more attention as its potential application is realized. This process has been revealed by high resolution electron microscopy in detail in this article. On the other hand, the radiation effects on the structure of human enamel are also characterized by high resolution electron microscopy. In order to reveal this phenomenon clearly, a great number of electron micrographs have been shown, and a physical mechanism is proposed. 26 references.

Wen, S.L. (Shanghai Institute of Ceramics, Academia Sinica (China))

1989-01-01

251

Quantitative Comparison of Spot Detection Methods in Live-Cell Fluorescence Microscopy Imaging  

Microsoft Academic Search

In live-cell fluorescence microscopy imaging, quantitative analysis of biological image data generally involves the detection of many subresolution objects, appearing as diffraction-limited spots. Due to acquisition limitations, the signal-to-noise ratio (SNR) can be ex- tremely low, making automated spot detection a very challenging task. In this paper, we quantitatively evaluate the performance of the most frequently used supervised and unsupervised

Ihor Smal; Marco Loog; Wiro J. Niessen; Erik H. W. Meijering

2009-01-01

252

Energy levels of few-electron quantum dots imaged and characterized by atomic force microscopy  

PubMed Central

Strong confinement of charges in few-electron systems such as in atoms, molecules, and quantum dots leads to a spectrum of discrete energy levels often shared by several degenerate states. Because the electronic structure is key to understanding their chemical properties, methods that probe these energy levels in situ are important. We show how electrostatic force detection using atomic force microscopy reveals the electronic structure of individual and coupled self-assembled quantum dots. An electron addition spectrum results from a change in cantilever resonance frequency and dissipation when an electron tunnels on/off a dot. The spectra show clear level degeneracies in isolated quantum dots, supported by the quantitative measurement of predicted temperature-dependent shifts of Coulomb blockade peaks. Scanning the surface shows that several quantum dots may reside on what topographically appears to be just one. Relative coupling strengths can be estimated from these images of grouped coupled dots.

Cockins, Lynda; Miyahara, Yoichi; Bennett, Steven D.; Clerk, Aashish A.; Studenikin, Sergei; Poole, Philip; Sachrajda, Andrew; Grutter, Peter

2010-01-01

253

Detective quantum efficiency of electron area detectors in electron microscopy  

Microsoft Academic Search

Recent progress in detector design has created the need for a careful side-by-side comparison of the modulation transfer function (MTF) and resolution-dependent detective quantum efficiency (DQE) of existing electron detectors with those of detectors based on new technology. We present MTF and DQE measurements for four types of detector: Kodak SO-163 film, TVIPS 224 charge coupled device (CCD) detector, the

G. McMullan; S. Chen; R. Henderson; A. R. Faruqi

2009-01-01

254

Life cycle of phytoreoviruses visualized by electron microscopy and tomography  

PubMed Central

Rice dwarf virus and Rice gall dwarf virus, members of the genus Phytoreovirus in the family Reoviridae,are known as agents of rice disease, because their spread results in substantial economic damage in many Asian countries. These viruses are transmitted via insect vectors, and they multiply both in the plants and in the insect vectors. Structural information about the viruses and their interactions with cellular components in the life cycle are essential for understanding viral infection and replication mechanisms. The life cycle of the viruses involves various cellular events such as cell entry, synthesis of viral genome and proteins, assembly of viral components, viral egress from infected cells, and intra- and intercellular transports. This review focuses on the major events underlying the life cycle of phytoreoviruses, which has been visualized by various electron microscopy (EM) imaging techniques, including cryo-electron microscopy and tomography, and demonstrates the advantage of the advanced EM imaging techniques to investigate the viral infection and replication mechanisms.

Miyazaki, Naoyuki; Nakagawa, Atsushi; Iwasaki, Kenji

2013-01-01

255

Electron microscopy of legionella and legionella-infected cells.  

PubMed

Those investigators who study the morphology of Legionella and Legionella-infected cells have greatly benefited from the superior resolution afforded by electron microscopy (EM). It can also be said with confidence that EM will continue to reveal as yet to be discovered features of this fascinating intracellular pathogen. In this chapter we detail our practical experience in the application of three transmission electron microscopy (TEM) techniques to the study of Legionella: conventional ultrastructural analysis, immuno-gold labeling, and negative staining. Each of these techniques has particular, well-defined applications, which are discussed in the context of our in-house developed methods. We invite researchers to try the methods given here in the study of Legionella, and adopt TEM as part of their research tools arsenal. PMID:23150403

Faulkner, Gary; Garduño, Rafael A

2013-01-01

256

Scanning electron microscopy of pulmonary alveolar capillary vessels  

PubMed Central

The pattern of subepithelial vessels in pulmonary alveoli of rabbits has been studied using scanning electron microscopy. Alveolar capillaries form a network of interconnecting vascular rings, most of which surround the periphery of type II cells of the alveolar epithelium. Individual capillaries contributing to the formation of adjacent rings follow a corrugated course with angulations located on the sites of junction with other capillaries completing the rings; the capillaries are covered by type I epithelial cells which also extend into and form the alveolar lining at the peripheral area of the interstices of the capillary network. Single type II cells form the alveolar lining at the centre of vascular rings. The pattern of pulmonary alveolar capillaries revealed by scanning electron microscopy is thus similar to that postulated by Weibel (1963) on the basis of transmission microscopic studies. Images

Alexander, I. G. S.; Ritchie, B. C.; Maloney, J. E.

1973-01-01

257

Electron microscopy of taste buds of the rat  

Microsoft Academic Search

The taste buds of the circumvallate papillae have been examined by electron microscopy in OsO4-fixed, PTA stained material or after KMnO4 fixation. The microvilli of the receptor cells have terminal dilatations which presumably give an increased surface area for transduction. The extracellular spaces at the necks of the receptor cells near the bases of the microvilli are interrupted by closed

E. G. Gray; K. C. Watkins

1965-01-01

258

Diabetic choroidal and iris vasculature scanning electron microscopy findings  

Microsoft Academic Search

Scanning Electron Microscopy (SEM) was used to study vascular casts of twenty-four autopsy eyes taken from patients with long-standing insulin-dependent Diabetes Mellitus. These casts were compared to casts of ten ‘normal’ autopsy eyes from patients without a history of diabetes or other vascular disease. The SEM findings in the choroidal vessels of the diabetic eyes included: increased tortuosity, focal vascular

Andrzej W. Fryczkowski; Barton L. Hodes; Jonathan Walker I

1989-01-01

259

Nodular amyloidosis: differentiation from colloid milium by electron microscopy.  

PubMed

Nodular amyloidosis is a primary cutaneous amyloidosis characterized by the deposition of amyloid L-type fibril proteins in the dermis. Clinical history and routine histology may not be sufficient to differentiate nodular amyloidosis from colloid milium. We present a case of a 45-year-old man with nodular amyloidosis, whose diagnosis was confirmed by the characteristic appearance of filaments on electron microscopy. PMID:19542924

Lai, Kimberly W; Lambert, Emily; Coleman, Stephen; Scott, Glynis; Mercurio, Mary Gail

2009-07-01

260

Intracellular localisation of phytochrome in oat coleoptiles by electron microscopy  

Microsoft Academic Search

We have analysed the intracellular localisation of phytochrome in oat coleoptile cells by electron microscopy and confirm and extend light-microscopical findings of previous authors. We used indirect immuno-labeling with polyclonal antibodies against 60-KDa phytochrome from etiolated oat seedlings, and a gold-coupled second antibody, on ultrathin sections of LR-white-embedded material. In dark-grown seedlings, phytochrome-labeling is distributed diffusely throughout the cytoplasm. Organelles

V. Speth; V. Otto; E. Schäfer

1986-01-01

261

Molybdenum nitride nanoparticles — high-resolution transmission electron microscopy study  

Microsoft Academic Search

The structure and size of molybdenum nitride nanoparticles were investigated using high-resolution transmission electron microscopy (HRTEM). Typical sizes of the particles were between 3 and 5 nm and they were mostly clustered together. High-resolution lattice imaging shows that the particles are single crystalline in nature and defect free. Two different phases of molybdenum nitride, ?-Mo2N (cubic) and ?-MoN (hexagonal) were identified.

J. Chaudhuri; L. Nyakiti; R. Lee; Y. Ma; P. Li; Q. L. Cui; L. H. Shen

2007-01-01

262

Preparation of disk foils for transmission electron microscopy  

Microsoft Academic Search

A method involving copper plating, mechanical lapping, electrolytic thinning, spark machining and perforating is described for the preparation of self-supporting disk foils of silicon-iron for transmission electron microscopy. Disk foils are most useful when the internal structure of metal specimens must be examined near free surfaces. They have the advantage that many distortion-free transparent areas can be observed in one

K R Carson; W J McG Tegart

1965-01-01

263

Probing the Plasma Membrane Structure of Immune Cells Through the Analysis of Membrane Sheets by Electron Microscopy  

PubMed Central

This chapter describes a method to generate plasma membrane sheets that are large enough to visualize the membrane architecture and perform quantitative analyses of protein distributions. This procedure places the sheets on electron microscopy grids, parallel to the imaging plane of the microscope, where they can be characterized by transmission electron microscopy. The basic principle of the technique is that cells are broken open (“ripped”) through mechanical forces applied by the separation of two opposing surfaces sandwiching the cell, with one of the surfaces coated onto an EM grid. The exposed inner membrane surfaces can then be visualized with electron dense stains and specific proteins can be detected with gold conjugated probes.

Lillemeier, Bjorn F.; Davis, Mark M.

2013-01-01

264

Fixation methods for electron microscopy of human and other liver  

PubMed Central

For an electron microscopic study of the liver, expertise and complicated, time-consuming processing of hepatic tissues and cells is needed. The interpretation of electron microscopy (EM) images requires knowledge of the liver fine structure and experience with the numerous artifacts in fixation, embedding, sectioning, contrast staining and microscopic imaging. Hence, the aim of this paper is to present a detailed summary of different methods for the preparation of hepatic cells and tissue, for the purpose of preserving long-standing expertise and to encourage new investigators and clinicians to include EM studies of liver cells and tissue in their projects.

Wisse, Eddie; Braet, Filip; Duimel, Hans; Vreuls, Celien; Koek, Ger; Olde Damink, Steven WM; van den Broek, Maartje AJ; De Geest, Bart; Dejong, Cees HC; Tateno, Chise; Frederik, Peter

2010-01-01

265

Scanning Transmission Electron Microscopy of Metal-Graphene Interaction  

NASA Astrophysics Data System (ADS)

Metal impurities, gold, chromium and titanium, have been deliberately introduced into graphene. The structural and topographic properties of doped graphene have then been studied by using conventional transmission electron and aberration corrected scanning transmission electron microscopy. Analysis revealed that metal atoms cluster preferentially in/on contaminated areas. Contrarily to observations that gold atoms do not adhere to clean patches of monolayer graphene, chromium and titanium were found to be more reactive with clean monolayer graphene, and the coverage was higher than for gold for the same evaporated amount.

Zan, R.; Bangert, U.; Ramasse, Q.; Novoselov, K. S.

2012-07-01

266

Assessment of Mechanical Durability Properties of Rock Materials Using Quantitative Microscopy and Image Analysis.  

National Technical Information Service (NTIS)

This report presents a project that focuses on the assessment of mechanical durability properties using quantitative microscopy. The project was financed by SGU under grant 03-1174/98. The aim has been to develop methods for assessment and presentation of...

J. E. Lindqvist U. Akesson K. Malaga B. Schouenborg M. Goeransson

2004-01-01

267

The importance of cantilever mechanics in the quantitative interpretation of Kelvin Probe Force Microscopy  

Microsoft Academic Search

A realistic interpretation of the measured contact potential difference (CPD) in Kelvin Probe Force Microscopy (KPFM) is crucial in order to extract quantitative information. Thus far, simulations of KPFM have treated the cantilever as a rigid object. We present a technique to simulate KPFM measurements by simulating a realistic three dimensional probe above a planar sample. We study three methods

Kevin J. Satzinger; Keith A. Brown; R. M. Westervelt

2011-01-01

268

Protein adsorption dynamics in cation-exchange chromatography quantitatively studied by confocal laser scanning microscopy  

Microsoft Academic Search

A self-contained research system based on the technique of confocal laser scanning microscopy (CLSM) was put up to quantitatively analyze the dynamics of protein adsorption to porous cation exchanger by mathematical modeling. Bovine serum albumin adsorption to the cation exchanger SP Sepharose FF was performed by batch adsorption and micro-flow cell in which protein concentration in single absorbent was visualized

Kun Yang; Shu Bai; Yan Sun

2008-01-01

269

Color metallography and electron microscopy techniques applied to the characterization of 413.0 aluminum alloys.  

PubMed

The influence on alloy 413.0 of the refinement and modification of its microstructure was analyzed by means of several microscopy techniques, as well as the effect of the application of high pressure during solidification. For each treatment and solidification pressure condition employed, the most suitable microscopy techniques for identifying and characterizing the phases present were investigated. Color metallography and electron microscopy techniques were applied to the qualitative microstructural analysis. Volume fraction and grain size of the primary ?-Al were characterized by quantitative metallographic techniques. The results show that the effect caused by applying high pressure during solidification of the alloy is more pronounced than that caused by modification and refinement of the microstructure when it solidifies at atmospheric pressure. Furthermore, it has been shown that, for Al-Si alloy characterization, when aiming to characterize the primary ?-Al phase, optical color metallography observed under crossed polarized light plus a sensitive tint filter is the most suitable technique. When the goal is to characterize the eutectic Si, the use of optical color metallography or electron microscopy is equally valid. The characterization of iron-rich intermetallic compounds should preferably be performed by means of backscattered electron imaging. PMID:23701972

Vander Voort, George; Asensio-Lozano, Juan; Suárez-Peña, Beatriz

2013-05-24

270

Investigation of the structure of nanocrystalline refractory oxides by X-ray diffraction, electron microscopy, and atomic force microscopy  

Microsoft Academic Search

The structures of nanocrystalline fibrous powders of refractory oxides have been investigated by different methods: determination\\u000a of coherent-scattering regions, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic-force\\u000a microscopy (AFM). The sizes of nanograins of different crystalline phases of refractory metal oxides have been determined\\u000a during the formation of these nanograins and the dynamics of their growth during heat

T. M. Ulyanova; L. V. Titova; S. V. Medichenko; Yu. G. Zonov; T. E. Konstantinova; V. A. Glazunova; A. S. Doroshkevich; T. A. Kuznetsova

2006-01-01

271

Interactions of elastic and rigid vesicles with human skin in vitro: electron microscopy and two-photon excitation microscopy  

Microsoft Academic Search

Interactions between vesicle formulations and human skin were studied, in vitro, in relation to their composition and elasticity. The skin ultrastructure was investigated using transmission electron microscopy (TEM), freeze-fracture electron microscopy (FFEM) and two-photon fluorescence microscopy (TPE). The main difference between the vesicle formulations was their elasticity. Elastic vesicle formulations contained bilayer forming surfactants\\/lipids and single-chain surfactant octaoxyethylenelaurate-ester (PEG-8-L), whereas

Benedicte A. I. van den Bergh; Jurrien Vroom; Hans Gerritsen; Hans E. Junginger; Joke A. Bouwstra

1999-01-01

272

Molecular and Cellular Quantitative Microscopy: theoretical investigations, technological developments and applications to neurobiology  

NASA Astrophysics Data System (ADS)

This PhD project aims at the development and evaluation of microscopy techniques for the quantitative detection of molecular interactions and cellular features. The primarily investigated techniques are F?rster Resonance Energy Transfer imaging and Fluorescence Lifetime Imaging Microscopy. These techniques have the capability to quantitatively probe the biochemical environment of fluorophores. An automated microscope capable of unsupervised operation has been developed that enables the investigation of molecular and cellular properties at high throughput levels and the analysis of cellular heterogeneity. State-of-the-art Förster Resonance Energy Transfer imaging, Fluorescence Lifetime Imaging Microscopy, Confocal Laser Scanning Microscopy and the newly developed tools have been combined with cellular and molecular biology techniques for the investigation of protein-protein interactions, oligomerization and post-translational modifications of ?-Synuclein and Tau, two proteins involved in Parkinson’s and Alzheimer’s disease, respectively. The high inter-disciplinarity of this project required the merging of the expertise of both the Molecular Biophysics Group at the Debye Institute - Utrecht University and the Cell Biophysics Group at the European Neuroscience Institute - G?ttingen University. This project was conducted also with the support and the collaboration of the Center for the Molecular Physiology of the Brain (Göttingen), particularly with the groups associated with the Molecular Quantitative Microscopy and Parkinson’s Disease and Aggregopathies areas. This work demonstrates that molecular and cellular quantitative microscopy can be used in combination with high-throughput screening as a powerful tool for the investigation of the molecular mechanisms of complex biological phenomena like those occurring in neurodegenerative diseases.

Esposito, Alessandro

2006-05-01

273

High-resolution environmental transmission electron microscopy: modeling and experimental verification.  

PubMed

Quantitative modeling for high-resolution (phase contrast) gas cell environmental transmission electron microscopy (ETEM) imaging is presented in this paper. Concepts of pre-specimen scattering object (PreSO) and post-specimen scattering object (PoSO) are introduced to explain electron scattering caused by gas and window membranes associated with the gas environmental cell (E-cell). PreSO preserves the structural phase information and the effect can be evaluated by averaging the contrast transfer functions (CTFs) over random electron scattering. PoSO is treated as information loss and the unscattered electrons play a major role in determining the ETEM image quality. The theoretical model is compared and matched well with our systematic gas ETEM experimental results under various gas pressures. Extension of our approach to the aberration-corrected ETEM is discussed. PMID:23427290

Suzuki, Makoto; Yaguchi, Toshie; Zhang, Xiao Feng

2013-02-20

274

Correlative cryo-electron tomography and optical microscopy of cells.  

PubMed

The biological processes occurring in a cell are complex and dynamic, and to achieve a comprehensive understanding of the molecular mechanisms underlying these processes, both temporal and spatial information is required. While cryo-electron tomography (cryoET) provides three-dimensional (3D) still pictures of near-native state cells and organelles at molecular resolution, fluorescence light microscopy (fLM) offers movies of dynamic cellular processes in living cells. Combining and integrating these two commonly used imaging modalities (termed correlative microscopy) provides a powerful means to not only expand the imaging scale and resolution but also to complement the dynamic information available from optical microscopy with the molecular-level, 3D ultrastructure detail provided by cryoET. As such, a correlative approach performed on a given specimen can provide high resolution snapshots of dynamic cellular events. In this article, I review recent advances in correlative light microscopy and cryoET and discuss major findings made available by applying this method. PMID:23962486

Zhang, Peijun

2013-08-17

275

TOPICAL REVIEW: Low energy electron point source microscopy: beyond imaging  

NASA Astrophysics Data System (ADS)

Low energy electron point source (LEEPS) microscopy has the capability to record in-line holograms at very high magnifications with a fairly simple set-up. After the holograms are numerically reconstructed, structural features with the size of about 2 nm can be resolved. The achievement of an even higher resolution has been predicted. However, a number of obstacles are known to impede the realization of this goal, for example the presence of electric fields around the imaged object, electrostatic charging or radiation induced processes. This topical review gives an overview of the achievements as well as the difficulties in the efforts to shift the resolution limit of LEEPS microscopy towards the atomic level. A special emphasis is laid on the high sensitivity of low energy electrons to electrical fields, which limits the structural determination of the imaged objects. On the other hand, the investigation of the electrical field around objects of known structure is very useful for other tasks and LEEPS microscopy can be extended beyond the task of imaging. The determination of the electrical resistance of individual nanowires can be achieved by a proper analysis of the corresponding LEEPS micrographs. This conductivity imaging may be a very useful application for LEEPS microscopes.

Beyer, André; Gölzhäuser, Armin

2010-09-01

276

Subparticle Ultrafast Spectrum Imaging in 4D Electron Microscopy  

NASA Astrophysics Data System (ADS)

Single-particle imaging of structures has become a powerful methodology in nanoscience and molecular and cell biology. We report the development of subparticle imaging with space, time, and energy resolutions of nanometers, femtoseconds, and millielectron volts, respectively. By using scanning electron probes across optically excited nanoparticles and interfaces, we simultaneously constructed energy-time and space-time maps. Spectrum images were then obtained for the nanoscale dielectric fields, with the energy resolution set by the photon rather than the electron, as demonstrated here with two examples (silver nanoparticles and the metallic copper-vacuum interface). This development thus combines the high spatial resolution of electron microscopy with the high energy resolution of optical techniques and ultrafast temporal response, opening the door to various applications in elemental analysis as well as mapping of interfaces and plasmonics.

Yurtsever, Aycan; van der Veen, Renske M.; Zewail, Ahmed H.

2012-01-01

277

Scanning and Transmission Electron Microscopy of 'Rickettsia rickettsii' Propagated in Cell Culture.  

National Technical Information Service (NTIS)

Scanning electron microscopy utilizing critical-point drying and transmission electron microscopy employing air-dried agar pseudoreplicas and critical-point dried carbon replicas were used to study the surface of Rickettsia rickettsii propagated in cell c...

C. E. Pedersen J. D. Gangemi S. J. Gourlay A. F. Hegyeli

1976-01-01

278

New immunolatex spheres: visual markers of antigens on lymphocytes for scanning electron microscopy  

PubMed Central

New immunochemical reagents consisting of antibodies bound to small latex spheres were used as visual markers for the detection and localization of cell surface antigens by scanning electron microscopy. Cross-linked latex spheres of various sizes from 300 to 3,4000 A in diameter were synthesized by aqueous emulsion copolymerization of methacrylate derivatives containing hydroxyl and carboxyl functional groups. Proteins and other molecules containing primary amino groups were covalently bonded to the acrylic spheres under a variety of mild conditions by the aqueous carbodiimide, cyanogen bromide, and glutaraldehyde methods. For use in the indirect immunochemical-labeling technique, goat antibodies directed against rabbit immunoglobulins were bonded to the spheres. These immunolatex reagents were shown to bind only to cells (red blood and lymphocytes) which had previously been sensitized with rabbit antibodies against cell surface antigens. Mouse spleen lymphocytes with exposed immunoglobulins on their surface (B cells) were labeled with these spheres and distinguished from unlabeled or T lymphocytes by scanning electron microscopy. The distribution of Ig receptors on lymphocytes was also studied using the spheres as visual markers. When lymphocytes were fixed with glutaraldehyde and subsequently labeled with the immunolatex reagents, a random distribution was observed by scanning electron microscopy; a patchy distribution was observed when unfixed lymphocytes were used. These results are consistent with studies using ferritin-labeled antibodies (S. De Petris and M. Raff. 1973. Nature [Lond.]. 241:257.) and support the view that Ig receptors on lymphocytes undergo translational diffusion. In addition to serving as visual markers for scanning electron microscopy, these latex spheres tagged with fluorescent or radioactive molecules have applications as highly sensitive markers for fluorescent microscopy and as reagents for quantitative studies of cell surface antigens and other receptors.

1975-01-01

279

Total internal reflection holographic microscopy (TIRHM) for quantitative phase characterization of cell-substrate adhesion  

NASA Astrophysics Data System (ADS)

Total Internal Reflection Holographic Microscopy (TIRHM) combines near-field microscopy with digital holography to produce a new form of near-field phase microscopy. Using a prism in TIR as a near-field imager, the presence of microscopic organisms, cell-substrate interfaces, and adhesions, causes relative refractive index (RRI) and frustrated TIR (f-TIR) to modulate the object beam's evanescent wave phase front. Quantitative phase images of test specimens such as Amoeba proteus, Dictyostelium Discoideum and cells such as SKOV-3 ovarian cancer and 3T3 fibroblasts are produced without the need to introduce stains or fluorophores. The angular spectrum method of digital holography to compensate for tilt anamorphism due to the inclined TIR plane is also discussed. The results of this work conclusively demonstrate, for the first time, the integration of near-field microscopy with digital holography. The cellular images presented show a correlation between the physical extent of the Amoeba proteus plasma membrane and the adhesions that are quantitatively profiled by phase cross-sectioning of the holographic images obtained by digital holography. With its ability to quantitatively characterise cellular adhesion and motility, it is anticipated that TIRHM can be a tool for characterizing and combating cancer metastasis, as well as improving our understanding of morphogenesis and embryogenesis itself.

Ash, William Mason, III

280

Scanning electron microscopy of the human endometrium in pill users.  

PubMed

20 premenstrual endometrial biopsies were examined in 20 fertile women using combined conventional oral contraceptive pills (Anoviar-1) for periods from 1-15 years using both SEM and light microscopy. 3 types of endometria were detected. These were irregular secretory, suppressed, and atrophic endometria. Using scanning electron microscopy, the 1st type showed few ciliated cells with weak cilia as well as collapsed nonciliated cells. The 2nd type showed nonciliated cells with few signs of secretion. The 3rd showed rarely ciliated cells, flat secretory cells with no signs of secretion. The longer the duration of pill use, the more atrophic changes there were. Focal glandular proliferation was also detected. PMID:3632471

Nayel, S A; Gawad, A A; Sibai, F A; Ghanem, A A; Ollo, M M; Shams, A T; Hebaish, N A

1987-06-01

281

Electron microscopy: essentials for viral structure, morphogenesis and rapid diagnosis.  

PubMed

Electron microscopy (EM) should be used in the front line for detection of agents in emergencies and bioterrorism, on accounts of its speed and accuracy. However, the number of EM diagnostic laboratories has decreased considerably and an increasing number of people encounter difficulties with EM results. Therefore, the research on viral structure and morphologyant in EM diagnostic practice. EM has several technological advantages, and should be a fundamental tool in clinical diagnosis of viruses, particularly when agents are unknown or unsuspected. In this article, we review the historical contribution of EM to virology, and its use in virus differentiation, localization of specific virus antigens, virus-cell interaction, and viral morphogenesis. It is essential that EM investigations are based on clinical and comprehensive pathogenesis data from light or confocal microscopy. Furthermore, avoidance of artifacts or false results is necessary to exploit fully the advantages while minimizing its limitations. PMID:23633074

Zhang, Ying; Hung, Tao; Song, Jingdong; He, Jinsheng

2013-05-01

282

Ultrahigh Voltage Electron Microscopy Links Neuroanatomy and Neuroscience/Neuroendocrinology  

PubMed Central

The three-dimensional (3D) analysis of anatomical ultrastructures is extremely important in most fields of biological research. Although it is very difficult to perform 3D image analysis on exact serial sets of ultrathin sections, 3D reconstruction from serial ultrathin sections can generally be used to obtain 3D information. However, this technique can only be applied to small areas of a specimen because of technical and physical difficulties. We used ultrahigh voltage electron microscopy (UHVEM) to overcome these difficulties and to study the chemical neuroanatomy of 3D ultrastructures. This methodology, which links UHVEM and light microscopy, is a useful and powerful tool for studying molecular and/or chemical neuroanatomy at the ultrastructural level.

Sakamoto, Hirotaka; Kawata, Mitsuhiro

2012-01-01

283

Pars plana incisions of four patients: histopathology and electron microscopy.  

PubMed Central

The pathology of pars plana incisions of four patients is described: three with light microscopy and one with light and electron microscopy. Two eyes were removed because of choroidal melanoma, immediately and 8 days after vitrectomy and transvitreous retinal biopsy. Considerable disruption of tissues surrounding the pars plana incisions was observed. Vitreous was incarcerated in the wounds, which healed with granulation tissue. One eye was examined 4 months after vitrectomy for diabetic retinopathy and a failed pars plana filtering operation. It contained fibrovascular ingrowth from all the incisions, infiltrating the vitreous base with granulation tissue and causing vitreous haemorrhage and retinal detachment. One eye was removed 1 year after vitrectomy for anterior hyaloidal fibrovascular proliferation and early phthisis. The wound had fibrous ingrowth histologically and evidence of active fibroplasia. Images

Koch, F H; Kreiger, A E; Spitznas, M; Glasgow, B; Foos, R Y; Yoshizumi, M O

1995-01-01

284

High-resolution electron microscopy of advanced materials  

SciTech Connect

This final report chronicles a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The High-Resolution Electron Microscopy Facility has doubled in size and tripled in quality since the beginning of the three-year period. The facility now includes a field-emission scanning electron microscope, a 100 kV field-emission scanning transmission electron microscope (FE-STEM), a 300 kV field-emission high-resolution transmission electron microscope (FE-HRTEM), and a 300 kV analytical transmission electron microscope. A new orientation imaging microscope is being installed. X-ray energy dispersive spectrometers for chemical analysis are available on all four microscopes; parallel electron energy loss spectrometers are operational on the FE-STEM and FE-HRTEM. These systems enable evaluation of local atomic bonding, as well as chemical composition in nanometer-scale regions. The FE-HRTEM has a point-to-point resolution of 1.6 {angstrom}, but the resolution can be pushed to its information limit of 1 {angstrom} by computer reconstruction of a focal series of images. HRTEM has been used to image the atomic structure of defects such as dislocations, grain boundaries, and interfaces in a variety of materials from superconductors and ferroelectrics to structural ceramics and intermetallics.

Mitchell, T.E.; Kung, H.H.; Sickafus, K.E.; Gray, G.T. III; Field, R.D.; Smith, J.F. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

1997-11-01

285

Direct quantification of ordering at a solid-liquid interface using aberration corrected transmission electron microscopy.  

PubMed

We have used aberration corrected in situ transmission electron microscopy to study the interface between liquid Al and different sapphire facet planes, including quantitative analysis of the degree of residual contrast delocalization, ensuring that the experimental contrast perturbations can be associated with density perturbations in the liquid. The results confirm that the liquid is ordered at the interface, and the degree of ordering varies as a function of the sapphire facet planes, with a decreasing degree of order according to (0006) >(1210) >(1012) ? (1014). PMID:23473172

Gandman, Maria; Kauffmann, Yaron; Koch, Christoph T; Kaplan, Wayne D

2013-02-20

286

Visualizing Gold Nanoparticle Uptake in Live Cells with Liquid Scanning Transmission Electron Microscopy  

PubMed Central

The intracellular uptake of 30 nm diameter gold nanoparticles (Au-NPs) was studied at the nanoscale in pristine eukaryotic cells. Live COS-7 cells were maintained in a microfluidic chamber and imaged using scanning transmission electron microscopy. A quantitative image analysis showed that Au-NPs bound to the membranes of vesicles, possibly lysosomes, and occupied 67% of the available surface area. The vesicles accumulated to form a micrometer-sized cluster after 24 h of incubation. Two clusters were analyzed and found to consist of 117 ± 9 and 164 ± 4 NP-filled vesicles.

2011-01-01

287

Scanning electron microscopy and energy dispersive analysis: applications in the field of cultural heritage.  

PubMed

Scanning electron microscopy has been extensively used for the material characterization of objects of artistic and archaeological importance, especially in combination with energy dispersive X-ray microanalysis (SEM/EDX). The advantages and limitations of SEM/EDX are presented in a few case studies: analysis of pigments in cross-sections of paint layers, quantitative analysis of archaeological glass from the Roman period excavated in Ephesos/Turkey, and investigations on glasses with medieval composition concerning their weathering stability and degradation phenomena. PMID:17031630

Schreiner, Manfred; Melcher, Michael; Uhlir, Katharina

2006-10-10

288

The origins and evolution of freeze-etch electron microscopy.  

PubMed

The introduction of the Balzers freeze-fracture machine by Moor in 1961 had a much greater impact on the advancement of electron microscopy than he could have imagined. Devised originally to circumvent the dangers of classical thin-section techniques, as well as to provide unique en face views of cell membranes, freeze-fracturing proved to be crucial for developing modern concepts of how biological membranes are organized and proved that membranes are bilayers of lipids within which proteins float and self-assemble. Later, when freeze-fracturing was combined with methods for freezing cells that avoided the fixation and cryoprotection steps that Moor still had to use to prepare the samples for his original invention, it became a means for capturing membrane dynamics on the millisecond time-scale, thus allowing a deeper understanding of the functions of biological membranes in living cells as well as their static ultrastructure. Finally, the realization that unfixed, non-cryoprotected samples could be deeply vacuum-etched or even freeze-dried after freeze-fracturing opened up a whole new way to image all the other molecular components of cells besides their membranes and also provided a powerful means to image the interactions of all the cytoplasmic components with the various membranes of the cell. The purpose of this review is to outline the history of these technical developments, to describe how they are being used in electron microscopy today and to suggest how they can be improved in order to further their utility for biological electron microscopy in the future. PMID:21844598

Heuser, John E

2011-01-01

289

An electron microscopy investigation of tin-molybdenum oxides  

NASA Astrophysics Data System (ADS)

Tin-molybdenum oxides prepared by the calcination of precipitates at high temperatures have been investigated by electron microscopy. The solids, which adopt the rutile-related tin(IV) oxide-type structure, are composed of crystalline particles containing planar defects, some of which have been characterized as twin boundaries. Although molybdenum has been found to be concentrated at these planar faults the examination of pure tin(IV) oxide prepared by similar methods shows that their formation is not dependent on the presence of molybdenum. It is suggested that molybdenum segregates to the twin boundaries during the calcination process to accommodate itself in more favorable coordination.

Berry, Frank J.; Hallett, Christopher; Loretto, Michael H.

1985-07-01

290

Catching HIV 'in the act' with 3D electron microscopy.  

PubMed

The development of a safe, effective vaccine to prevent HIV infection is a key step for controlling the disease on a global scale. However, many aspects of HIV biology make vaccine design problematic, including the sequence diversity and structural variability of the surface envelope glycoproteins and the poor accessibility of neutralization-sensitive epitopes on the virus. In this review, we discuss recent progress in understanding HIV in a structural context using emerging tools in 3D electron microscopy, and outline how some of these advances could be important for a better understanding of mechanisms of viral entry and for vaccine design. PMID:23850373

Earl, Lesley A; Lifson, Jeffrey D; Subramaniam, Sriram

2013-07-11

291

Microstructural studies of dental amalgams using analytical transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Dental amalgams have been used for centuries as major restorative materials for decaying teeth. Amalgams are prepared by mixing alloy particles which contain Ag, Sn, and Cu as the major constituent elements with liquid Hg. The study of microstructure is essential in understanding the setting reactions and improving the properties of amalgams. Until the work reported in this dissertation, optical microscopy (OM), scanning electron microscopy (SEM), and x-ray diffractometry (XRD) were used commonly to analyze amalgam microstructures. No previous systematic transmission electron microscopy (TEM) study has been performed due to sample preparation difficulties and composite structure of dental amalgams. The goal of this research was to carry out detailed microstructural and compositional studies of dental amalgams. This was accomplished using the enhanced spatial resolution of the TEM and its associated microanalytical techniques, namely, scanning transmission electron microscopy (STEM), x-ray energy dispersive spectroscopy (XEDS) and micro-microdiffraction (mumuD). A new method was developed for thinning amalgam samples to electron transparency using the "wedge technique." Velvalloy, a low-Cu amalgam, and Tytin, a high-Cu amalgam, were the two amalgams characterized. Velvalloy is composed of a Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) matrix surrounding unreacted Agsb3Sn (gamma) particles. In addition, hitherto uncharacterized reaction layers between Agsb3Sn(gamma)/Agsb2Hgsb3\\ (gammasb2)\\ and\\ Agsb2Hgsb3\\ (gammasb1)/HgSnsb{7-9}\\ (gammasb2) were observed and analyzed. An Ag-Hg-Sn (betasb1) phase was clearly identified for the first time. In Tytin, the matrix consists of Agsb2Hgsb3\\ (gammasb1) grains. Fine precipitates of Cusb6Snsb5\\ (etasp') are embedded inside the gammasb1 and at the grain boundaries. These precipitates are responsible for the improved creep resistance of Tytin compared to Velvalloy. The additional Cu has completely eliminated the gammasb2 phase which is the weakest component of amalgams. Ag-Hg-Sn (betasb1) and large grains of Cusb6Snsb5\\ (etasp') are found adjacent to the unreacted alloy particles. Tytin alloy particles contain Cusb3Sn\\ (epsilon) precipitates in a matrix of Agsb3Sn (gamma) and Agsb4Sn\\ (beta). SEM was used to correlate the TEM findings in the context of the general microstructure. The results are in good agreement with those published in the literature. The microstructural details reported here, many of which were not previously available, will help provide insight into the deformation mechanisms of dental amalgams.

Hooghan, Tejpal Kaur

292

[Scanning electron microscopy with corrosive preparations in pathology].  

PubMed

Methodical aspects of scanning electron microscopy of corrosion preparations (SEMCP) are described on the basis of the authors' own data and those from the literature. A critical analysis of the currently used injection masses and the results obtained by SEMCP is given. New data are emphasized, introduced into pathological morphology after the adoption of SEMCP. Relief formations of casts of the blood and lymph vessels in health and disease are classified. The prospects of and main approaches to the use of SEMCP in pathological morphology are discussed. PMID:7073513

Karaganov, Ia L; Mironov, A A; Mironov, V A

1982-01-01

293

Photonic near-field imaging in multiphoton photoemission electron microscopy  

NASA Astrophysics Data System (ADS)

We report the observation of optical near fields in a photonic waveguide of conductive indium tin oxide (ITO) using multiphoton photoemission electron microscopy (PEEM). Nonlinear two-photon photoelectron emission is enhanced at field maxima created by interference between incident 410-nm and coherently excited guided photonic waves, providing strong phase contrast. Guided modes are observed under both transverse magnetic field (TM) and transverse electric field (TE) polarized illuminations and are consistent with classical electromagnetic theory. Implications on the role of multiphoton PEEM in optical near-field imaging are discussed.

Fitzgerald, J. P. S.; Word, R. C.; Saliba, S. D.; Könenkamp, R.

2013-05-01

294

Depth profiling of integrated circuits with thermal wave electron microscopy  

NASA Astrophysics Data System (ADS)

Nondestructive depth profiling of integrated circuits was performed with thermal wave electron microscopy at a 640 kHz modulation frequency. Images were obtained at both a shallow penetration (near surface) and a deep penetration (subsurface) phase setting. It is the deep penetration image that provides new data and the capability for the nondestructive detection of subsurface flaws in integrated circuits. It is possible, with a knowledge of the thermal properties of the circuit elements, to measure at what depth a flaw or defect occurs.

Rosencwaig, A.

1980-11-01

295

Analytical electron microscopy study of radioactive ceramic waste form  

SciTech Connect

A ceramic waste form has been developed to immobilize the halide high-level waste stream from electrometallurgical treatment of spent nuclear fuel. Analytical electron microscopy studies, using both scanning and transmission instruments, have been performed to characterize the microstructure of this material. The microstructure consists primarily of sodalite granules (containing the bulk of the halides) bonded together with glass. The results of these studies are discussed in detail. Insight into the waste form fabrication process developed as a result of these studies is also discussed.

O'Holleran, T. P.; Sinkler, W.; Moschetti, T. L.; Johnson, S. G.; Goff, K. M.

1999-11-11

296

Correlative Fluorescence Microscopy and Scanning Transmission Electron Microscopy of Quantum Dot Labeled Proteins in Whole Cells in Liquid  

PubMed Central

Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7 × 12 nm were visible in a 5 ?m thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs.

Dukes, Madeline J.; Peckys, Diana B.; de Jonge, Niels

2010-01-01

297

Subsurface characterization of carbon nanotubes in polymer composites via quantitative electric force microscopy.  

PubMed

Subsurface characterization of carbon nanotubes (CNTs) dispersed in free-standing polymer composite films was achieved via quantitative electric force microscopy (EFM). The effects of relative humidity, EFM probe geometry, tip-sample distance and bias voltage on the EFM contrast were studied. Non-parabolic voltage dependence of the EFM signal of subsurface CNTs in polymer composites was observed and a new mechanism was proposed taking consideration of capacitive coupling as well as coulombic coupling. We anticipate that this quantitative EFM technique will be a useful tool for non-destructive subsurface characterization of high dielectric constant nanostructures in low dielectric constant matrices. PMID:20453284

Zhao, Minhua; Gu, Xiaohong; Lowther, Sharon E; Park, Cheol; Jean, Y C; Nguyen, Tinh

2010-05-07

298

Subsurface characterization of carbon nanotubes in polymer composites via quantitative electric force microscopy  

NASA Astrophysics Data System (ADS)

Subsurface characterization of carbon nanotubes (CNTs) dispersed in free-standing polymer composite films was achieved via quantitative electric force microscopy (EFM). The effects of relative humidity, EFM probe geometry, tip-sample distance and bias voltage on the EFM contrast were studied. Non-parabolic voltage dependence of the EFM signal of subsurface CNTs in polymer composites was observed and a new mechanism was proposed taking consideration of capacitive coupling as well as coulombic coupling. We anticipate that this quantitative EFM technique will be a useful tool for non-destructive subsurface characterization of high dielectric constant nanostructures in low dielectric constant matrices.

Zhao, Minhua; Gu, Xiaohong; Lowther, Sharon E.; Park, Cheol; Jean, Y. C.; Nguyen, Tinh

2010-06-01

299

Development of a multifunctional surface analysis system based on a nanometer scale scanning electron beam: Combination of ultrahigh vacuum-scanning electron microscopy, scanning reflection electron microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy  

Microsoft Academic Search

We have developed a multifunctional surface analysis system based on a scanning electron beam for nanofabrication and characterization of surface reactions for fabrication processes. The system performs scanning electron microscopy (SEM), scanning reflection electron microscopy (SREM), Auger electron spectroscopy (AES), and x-ray photoelectron spectroscopy. Nanometer scale resolution is obtained for ultrahigh vacuum (UHV)-SEM while the mechanical pumping instruments are operated.

Heiji Watanabe; Masakazu Ichikawa

1996-01-01

300

High sensitivity piezomagnetic force microscopy for quantitative probing of magnetic materials at the nanoscale.  

PubMed

Accurate scanning probing of magnetic materials at the nanoscale is essential for developing and characterizing magnetic nanostructures, yet quantitative analysis is difficult using the state of the art magnetic force microscopy, and has limited spatial resolution and sensitivity. In this communication, we develop a novel piezomagnetic force microscopy (PmFM) technique, with the imaging principle based on the detection of magnetostrictive response excited by an external magnetic field. In combination with the dual AC resonance tracking (DART) technique, the contact stiffness and energy dissipation of the samples can be simultaneously mapped along with the PmFM phase and amplitude, enabling quantitative probing of magnetic materials and structures at the nanoscale with high sensitivity and spatial resolution. PmFM has been applied to probe magnetic soft discs and cobalt ferrite thin films, demonstrating it as a powerful tool for a wide range of magnetic materials. PMID:23720016

Chen, Qian Nataly; Ma, Feiyue; Xie, Shuhong; Liu, Yuanming; Proksch, Roger; Li, Jiangyu

2013-05-29

301

Biomechanics of DNA structures visualized by 4D electron microscopy  

PubMed Central

We present a technique for in situ visualization of the biomechanics of DNA structural networks using 4D electron microscopy. Vibrational oscillations of the DNA structure are excited mechanically through a short burst of substrate vibrations triggered by a laser pulse. Subsequently, the motion is probed with electron pulses to observe the impulse response of the specimen in space and time. From the frequency and amplitude of the observed oscillations, we determine the normal modes and eigenfrequencies of the structures involved. Moreover, by selective “nano-cutting” at a given point in the network, it was possible to obtain Young’s modulus, and hence the stiffness, of the DNA filament at that position. This experimental approach enables nanoscale mechanics studies of macromolecules and should find applications in other domains of biological networks such as origamis.

Lorenz, Ulrich J.; Zewail, Ahmed H.

2013-01-01

302

Some applications of microanalytical electron microscopy in materials research  

SciTech Connect

Electron microscopy has made extraordinary progress over the past 30 years and has become an indispensible tool for research in materials science. In this paper a review is given of some applications of microdiffraction and microanalysis in our current materials science research projects at the University of California, Berkeley. The topics discussed include: (1) The problem of solute atom partitioning in steels; this includes the difficulties of measuring carbon contents and methods of utilizing diffraction, lattice imaging, energy dispersive x-ray (EDXS) and electron energy loss (EELS) spectroscopies and atom probe analysis will be illustrated. (2) Utilization of CBED and EDXS techniques in zirconia ceramics research. (3) Applications of CBED to the study of el-Fe2O3 particles used in magnetic recording systems. (4) Applications of CBED and EDXS to rare earth permanent magnets. (5) Channelling enhanced microanalysis. 50 refs., 21 figs.

Thomas, G.

1985-10-01

303

Self-reference extended depth-of-field quantitative phase microscopy  

Microsoft Academic Search

This paper describes a novel quantitative phase microscopy based on a simple self-referencing scheme using Michelson interferometry. In order to achieve the homogeneous reference field for accurate phase measurement, the imaging field-of-view (FOV) is split onto the sample and homogenous background areas. The reference field can be generated by rotating the relative position of the sample and homogenous background in

Jaeduck Jang; Chae Yun Bae; Je-Kyun Park; Jong Chul Ye

2010-01-01

304

Developments in cell biology for quantitative immunoelectron microscopy based on thin sections: a review  

Microsoft Academic Search

Quantitative immunoelectron microscopy uses ultrathin sections and gold particle labelling to determine distributions of molecules\\u000a across cell compartments. Here, we review a portfolio of new methods for comparing labelling distributions between different\\u000a compartments in one study group (method 1) and between the same compartments in two or more groups (method 2). Specimen samples\\u000a are selected unbiasedly and then observed and

Terry M. Mayhew; John M. Lucocq

2008-01-01

305

Quantitative analysis on collagen morphology in aging skin based on multiphoton microscopy  

Microsoft Academic Search

Multiphoton microscopy was employed for monitoring the structure changes of mouse dermis collagen in the intrinsic- or the extrinsic-age-related processes in vivo. The characteristics of textures in different aging skins were uncovered by fast Fourier transform in which the orientation index and bundle packing of collagen were quantitatively analyzed. Some significant differences in collagen-related changes are found in different aging

Shulian Wu; Hui Li; Hongqin Yang; Xiaoman Zhang; Zhifang Li; Shufei Xu

2011-01-01

306

Golgi apparatus analyzed by cryo-electron microscopy.  

PubMed

In 1898, the Golgi apparatus was discovered by light microscopy, and since the 1950s, the ultrastructure composition is known by electron microscopic investigation. The complex three-dimensional morphology fascinated researchers and was sometimes even the driving force to develop novel visualization techniques. However, the highly dynamic membrane systems of Golgi apparatus are delicate and prone to fixation artifacts. Therefore, the understanding of Golgi morphology and its function has been improved significantly with the development of better preparation methods. Nowadays, cryo-fixation is the method of choice to arrest instantly all dynamic and physiological processes inside cells, tissues, and small organisms. Embedded in amorphous ice, such samples can be further processed by freeze substitution or directly analyzed in their fully hydrated state by cryo-electron microscopy and tomography. Even though the overall morphology of vitrified Golgi stacks is comparable to well-prepared and resin-embedded samples, previously unknown structural details can be observed solely based on their native density. At this point, any further improvement of sample preparation would gain novel insights, perhaps not in terms of general morphology, but on fine structural details of this dynamic organelle. PMID:23954988

Han, Hong-Mei; Bouchet-Marquis, Cedric; Huebinger, Jan; Grabenbauer, Markus

2013-08-18

307

Cytoplasmic Microtubular Images in Glutaraldehyde-Fixed Tissue Culture Cells by Electron Microscopy and by Immunofluorescence Microscopy  

Microsoft Academic Search

Electron microscopy and indirect immunofluorescence microscopy using monospecific tubulin antibodies were performed in parallel on glutaraldehyde-fixed tissue culture cells without osmium fixation. In order to reduce the excess aldehyde groups of the strongly crosslinked cellular matrix, which normally interfere with subsequent immunofluorescence microscopy, a mild NaBH4 treatment was introduced during or after the dehydration steps. Cells processed through the NaBH4

Klaus Weber; Peter C. Rathke; Mary Osborn

1978-01-01

308

Quantitative Analysis by Derivative Electronic Spectroscopy  

Microsoft Academic Search

Absorption and emission spectroscopy in the ultraviolet and visible regions, apart from being the earliest physical techniques of analysis, have great utility in solving a variety of structural and analytical problems [l-41. However, in many cases the quantitative determination of individual components in a mixture by UV-VIS spectroscopy becomes very difficult owing to the spectral similarities and overlapping of weak

L. Dixit; S. Ram

1985-01-01

309

Electron microscopy investigations of nanoparticles for cancer diagnostic applications  

NASA Astrophysics Data System (ADS)

This dissertation concerns electron microscopy characterization of magnetic (MNP) and surface enhanced Raman scattering (SERS) nanoparticles for in-vitro cancer diagnostic applications. Electron microscopy is an essential characterization tool owing to its (sub) nanometer spatial resolution. Structural information about the nanoparticles can be obtained using transmission electron microscopy (TEM), which can in turn be correlated to their physical characteristics. The scanning electron microscope (SEM) has excellent depth of field and can be effectively utilized to obtain high resolution information about nanoparticles binding onto cell surfaces. Part One of this thesis focuses on MNPs for bio-sensing and detection applications. As a preliminary study, chemically-synthesized, commercially-available iron oxide nanoparticles were compared against their laboratory-synthesized counterparts to assess their suitability for this application. The motivation for this initial study came about due to the lack of published data on commercially available iron oxide nanoparticles. TEM studies show that the latter are "beads" composed of multiple iron oxide cores encapsulated by a polymer shell, with large standard deviations in core diameter. Laboratory-synthesized iron oxide nanoparticles, on the other hand, are single core particles with small variations in diameter and therefore are expected to be better candidates for the required application. A key limitation in iron oxide nanoparticles is their relatively weak magnetic signals. The development of high moment Synthetic Anti-Ferromagnetic (SAF) nanoparticles aims to overcome this issue. SAFs are a novel class of MNPs fabricated using nanoimprint lithography, direct deposition of multilayer structure and final suspension into liquid medium (water). TEM analyses of cross-section specimens reveal that the SAFs possess characteristics similar to those of sputtered magnetic multilayer thin films. Their layered structure is preserved after a chemical etch. Magnetic measurements show a slight decrease in magnetic moment after ion milling. From TEM characterization, the introduction of oxygen into the copper release layer, prior the film deposition process, can effectively control the topography of the oxidized-copper grains and, consequently, lead to the production of SAF nanoparticles with flatter layers. Size distribution studies performed on SAFs fabricated using self-assembled stamps show that it is possible to produce monodisperse nanoparticles with diameters from 70 nm up. Part Two of the dissertation describes structural characterization experiments performed on Composite Organic-Inorganic Nanoparticles (COINs), which are a novel type of SERS nanoclusters formed by aggregating silver nanoparticles with Raman molecules, and then encapsulating them with an organic coating that stabilizes the aggregates and promotes subsequent functionalization with antibodies. Part Three of this dissertation focuses on the development and application of electron microscopy-based techniques to characterize the nanomaterial-biology interactions, to assess how, or indeed whether, nanoparticles are attaching to the cancer cells. The technique of negative staining was applied to simultaneously visualize inorganic nanoparticles and their biofunctionalized entities under the TEM and to verify the successful functionalization of nanoparticles with antibodies. The interpretation of the negatively-stained COINs was consistent with the EFTEM data. Next, the localization and characterization of CD54-functionalized COINs on the apicolateral portions of U937 leukemia cell lines was determined using TEM, SEM and Scanning Auger Microscopy. The analyses show that CD54 antigens are localized at a specific region on U937 leukemia cell surfaces. SEM imaging and SER spectroscopy correlation studies of different antibody-conjugated COINs attached onto different cancer cell lines show a direct correlation between the number of COINs binding to cells and the corresponding SER intensity. Finally, TEM was used to l

Koh, Ai Leen

310

The influence of foliation on the fragility of granitic rocks, image analysis and quantitative microscopy  

Microsoft Academic Search

Fabric-dependent anisotropy is important in understanding the mechanical behaviour of foliated rocks because the foliation creates mechanically weak discontinuities. Using optical microscopy, a foliation index (FIX) was calculated for a group of granitic rocks in southern Sweden that displays a range of textures from foliated to nonfoliated. Image analysis from scanning electron microscope with backscattered detector (SEM\\/BSE) images was used

Urban Åkesson; Jimmy Stigh; Jan Erik Lindqvist; Mattias Göransson

2003-01-01

311

Quantitative analysis of electron spectroscopic imaging series  

Microsoft Academic Search

We have developed new methods to quantify the data acquired by electron spectroscopic imaging (ESI) which are based on recording series of energy filtered images across inner shell loss edges or in the low loss region. From the series of ESI images, electron energy loss (EEL) spectra can be extracted for any given image area, i.e. each individual pixel or

J Mayer; U Eigenthaler; J. M Plitzko; F Dettenwanger

1997-01-01

312

Application of Electron Microscopy and Atomic Force Microscopy Techniques to the Ultrastructural Studies of DNA Complexes with Synthetic Oligopeptide  

Microsoft Academic Search

This paper presents the results of studies of DNA complexes with synthetic oligopeptide trivaline (TVP) by electron microscopy and atomic force microscopy (AFM). The AFM images of circular DNA complexes with TVP were obtained on traditionally used for AFM supporting substrate-mica as well as on alternative surface -modified highly ordered pyrolytic graphite (HOPG). Results show that elaborated methodical ways of

Larissa P. Martinkina; Dmitry V. Klinov; Victor V. Demin; Yuri Yu. Vengerov

313

Quantitative aspects of digital microscopy applied to cellular localization of heparin in smooth muscle cells  

NASA Astrophysics Data System (ADS)

High Resolution digital acquisition allows a great deal of flexibility in the types of questions that can be directed to microscopic samples. To eliminate subjective bias and provide quantitative results we have approached microscopy with an automated digital format. This mode can return quantitative data at high resolution over large fields. The digital format makes accessible data including [data segmentation]: multispectral colocalization, seeding and connectivity, particle size and shape distribution and population analysis. We have begun a program to investigate this approach using the confocal microscope. Scanning larger fields-of-view at lower spatial resolutions (e.g., low magnification objective) defines large maps that allow alignment of high spatial resolution (diffraction limited) sampling. The [objective] selection of the field-of-view with low spatial resolution reduces the subjective nature of the selection of a 'typical staining pattern'. High resolution digital scanning in three dimensions contribute both to the 'objective' nature of the analysis and allow for quantitation of characteristics not historically available/accessible. The complex carbohydrate heparin is implicated in tumor growth and wound healing by affecting angiogenesis, cell proliferation and motility. The internal localization of heparin within vascular cells appears to be a good predictor of the sensitivity of those cells to the action of heparin. Cells resistant to the antiproliferative action of heparin are able to sequester the heparin in large vacuoles whereas those cells sensitive to the carbohydrate do not exhibit these structures. We have applied our approach to QUANTITATIVE DIGITAL MICROSCOPY to the analysis of intracellular heparin distribution.

Johnston, Richard F.; Hanzel, David K.; Stack, Bob; Brandley, Brian; Castellot, John

1995-04-01

314

Identifying hexagonal boron nitride monolayers by transmission electron microscopy.  

PubMed

Multislice simulations in the transmission electron microscope (TEM) were used to examine changes in annular-dark-field scanning TEM (ADF-STEM) images, conventional bright-field TEM (BF-CTEM) images, and selected-area electron diffraction (SAED) patterns as atomically thin hexagonal boron nitride (h-BN) samples are tilted up to 500 mrad off of the [0001] zone axis. For monolayer h-BN the contrast of ADF-STEM images and SAED patterns does not change with tilt in this range, while the contrast of BF-CTEM images does change; h-BN multilayer contrast varies strongly with tilt for ADF-STEM imaging, BF-CTEM imaging, and SAED. These results indicate that tilt series analysis in ADF-STEM image mode or SAED mode should permit identification of h-BN monolayers from raw TEM data as well as from quantitative post-processing. PMID:22640966

Odlyzko, Michael L; Mkhoyan, K Andre

2012-06-01

315

Quantitative Vibrational Imaging by Hyperspectral Stimulated Raman Scattering Microscopy and Multivariate Curve Resolution Analysis  

PubMed Central

Spectroscopic imaging has been an increasingly critical approach for unveiling specific molecules in biological environments. Towards this goal, we demonstrate hyperspectral stimulated Raman loss (SRL) imaging by intra-pulse spectral scanning through a femtosecond pulse shaper. The hyperspectral stack of SRL images is further analyzed by a multivariate curve resolution (MCR) method to reconstruct quantitative concentration images for each individual component and retrieve the corresponding vibrational Raman spectra. Using these methods, we demonstrate quantitative mapping of dimethyl sulfoxide concentration in aqueous solutions and in fat tissue. Moreover, MCR is performed on SRL images of breast cancer cells to generate maps of principal chemical components along with their respective vibrational spectra. These results show the great capability and potential of hyperspectral SRL microscopy for quantitative imaging of complicated biomolecule mixtures through resolving overlapped Raman bands.

Zhang, Delong; Wang, Ping; Slipchenko, Mikhail N.; Ben-Amotz, Dor; Weiner, Andrew M.; Cheng, Ji-Xin

2013-01-01

316

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

Microsoft Academic Search

In this protocol, we describe a 3D imaging technique known as 'volume electron microscopy' or 'focused ion beam scanning electron microscopy (FIB\\/SEM)' applied to biological tissues. A scanning electron microscope equipped with a focused gallium ion beam, used to sequentially mill away the sample surface, and a backscattered electron (BSE) detector, used to image the milled surfaces, generates a large

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

2011-01-01

317

Characterization of protein immobilization on nanoporous gold using atomic force microscopy and scanning electron microscopy  

NASA Astrophysics Data System (ADS)

Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize a highly efficient approach for protein immobilization on NPG using N-hydroxysuccinimide (NHS) ester functionalized self-assembled monolayers on NPG with pore sizes in the range of tens of nanometres. Comparison of coupling under static versus flow conditions suggests that BSA (Bovine Serum Albumin) and IgG (Immunoglobulin G) can only be immobilized onto the interior surfaces of free standing NPG monoliths with good coverage under flow conditions. AFM is used to examine protein coverage on both the exterior and interior of protein modified NPG. Access to the interior surface of NPG for AFM imaging is achieved using a special procedure for cleaving NPG. AFM is also used to examine BSA immobilized on rough gold surfaces as a comparative study. In principle, the general approach described should be applicable to many enzymes, proteins and protein complexes since both pore sizes and functional groups present on the NPG surfaces are controllable.Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize a highly efficient approach for protein immobilization on NPG using N-hydroxysuccinimide (NHS) ester functionalized self-assembled monolayers on NPG with pore sizes in the range of tens of nanometres. Comparison of coupling under static versus flow conditions suggests that BSA (Bovine Serum Albumin) and IgG (Immunoglobulin G) can only be immobilized onto the interior surfaces of free standing NPG monoliths with good coverage under flow conditions. AFM is used to examine protein coverage on both the exterior and interior of protein modified NPG. Access to the interior surface of NPG for AFM imaging is achieved using a special procedure for cleaving NPG. AFM is also used to examine BSA immobilized on rough gold surfaces as a comparative study. In principle, the general approach described should be applicable to many enzymes, proteins and protein complexes since both pore sizes and functional groups present on the NPG surfaces are controllable. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10427f

Tan, Yih Horng; Schallom, John R.; Ganesh, N. Vijaya; Fujikawa, Kohki; Demchenko, Alexei V.; Stine, Keith J.

2011-08-01

318

Three-Dimensional Scanning Transmission Electron Microscopy of Biological Specimens  

PubMed Central

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

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

2010-01-01

319

Three-dimensional scanning transmission electron microscopy of biological specimens  

SciTech Connect

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

De Jonge, Niels [ORNL; Sougrat, Rachid [ORNL; Northan, Brian [Media Cybernetics, Inc.; Pennycook, Stephen J [ORNL

2010-01-01

320

Light collection efficiency and light transport in backscattered electron scintillator detectors in scanning electron microscopy.  

PubMed

Experimentally, scintillator detectors used in scanning electron microscopy (SEM) to record backscattered electrons (BSE) show a noticeable difference in detection efficiency in different parts of their active zones due to light losses transport in the optical part of the detector. A model is proposed that calculates the local efficiency of the active parts of scintillator detectors of arbitrary shapes. The results of these calculations for various designs are presented. PMID:11587323

Filippov, M N; Rau, E I; Sennov, R A; Boyde, A; Howell, P G

321

High-resolution microscopy of plasmon field distributions by scanning tunneling luminescence and photoemission electron microscopies  

NASA Astrophysics Data System (ADS)

The exploitation of plasmon resonances to promote the interaction between conjugated molecules and optical fields motivates intensive research. The objectives are to understand the mechanisms of plasmon-mediated interactions, and to realize molecularly- or atomically-precise metal nanostructures, combining field enhancements and optical antenna effects. In this review paper, we present examples of plasmonic-field mappings based on scanning tunneling microscope (STM)-induced light emission or multiphoton photoemission (PEEM), two techniques among those which offer today's best spatial resolutions for plasmon microscopy. An unfamiliar property of the junction of an STM is its ability to behave as a highly localized source of light. It can be exploited to probe optoelectronic properties, in particular plasmonic fields, with ultimate subnanometer spatial resolution, an advantage balanced by a sometimes delicate deconvolution of local-probe influence. Alternatively, local-probe disadvantages can be overcome by imaging the photoemitted electrons, using well-established electron optics. This allows obtaining two-dimensional intensity maps reflecting the unperturbed distribution of the optical near field. This approach provides full field spectroscopic images with a routine spatial resolution of the order of 20 nm (down to 5 nm with recent aberration corrected instruments).

Douillard, Ludovic; Charra, Fabrice

2012-10-01

322

Electron microscopy of viruses and virus-cell interactions.  

PubMed

Electron microscopy is a powerful tool to visualize viruses in diagnostic as well as in research settings for investigating viral structure and virus-cell interactions. Here, a simple but efficient method is described for demonstrating viruses by negative staining, and its limit is discussed. A prerequisite to obtain reliable information on virus-cell interactions is excellent preservation of cellular and viral ultrastructure. The crux is that during fixation and embedding, by applying conventional protocols about 50% of the lipids are lost, which results in loss of integrity of cell membranes. To achieve good preservation of cellular architectures, good contrast, and both high spatial and temporal resolution, methods for freezing, freeze-substitution, and freeze-etching are described and their applicability discussed mostly taking complicated built herpes viruses as examples. PMID:18617049

Wild, Peter

2008-01-01

323

Waveguide characterization with multi-photon photoemission electron microscopy  

NASA Astrophysics Data System (ADS)

Multi-photon photoemission electron microscopy (PEEM) images surface interactions of visible light with matter, showing electromagnetic (EM) waves that propagate at or near the surface. Images are interferometric, showing where incident and surface waves are in-phase (bright) and out-of-phase (dark), with strong contrast between regions of high and low rates of photoelectron emission. Interferogram analysis can determine the amplitude, wavelength, phase evolution, and propagation decay length of the surface waves. Most multi-photon PEEM studies focus on surface plasmon polaritons. We show that this technique can also be applied to conducting thin-film waveguides, measuring the properties of confined EM waves in a two-mode slab waveguide made of indium tin oxide on glass, which are consistent with waveguide theory. This research was funded by the US Department of Energy Basic Science Office under contract DE-FG02-10ER46406.

Fitzgerald, J. P. S.; Word, Robert C.; Saliba, Sebastian; Koenenkamp, Rolf

2012-10-01

324

Transmission Electron Microscopy (TEM) investigations of ancient Egyptian cosmetic powders  

NASA Astrophysics Data System (ADS)

The processing technologies available during the time of ancient Egypt are of present concern to the field of Archaeology and Egyptology. Materials characterization is the best tool for establishing the processing history of archaeological objects. In this study, transmission electron microscopy (TEM) is used, in addition to other techniques, for phase identification and study of the microstructure and characteristic defect structures in ancient Egyptian cosmetic powders. These powders generally consist of a mix of Pb-containing mineral phases: galena (PbS), cerussite (PbCO3), and phosgenite (Pb2Cl2CO3), among others. Modern materials are fabricated according to recipes found in ancient texts to mimic the processing of ancient times and to compare with the archaeological specimens. In particular, a comparison between the dislocation structures of PbS crystals deformed in the laboratory and PbS from archaeological specimens from the collections of the Louvre Museum is presented .

Deeb, C.; Walter, P.; Castaing, J.; Penhoud, P.; Veyssière, P.

325

Performance of asbestos fibre counting laboratories by transmission electron microscopy.  

PubMed

In France, the owners of buildings have been obliged since February 1996 to ascertain whether asbestos has been incorporated into surfacing materials, insulation products or false ceilings. In certain circumstances, there is also a requirement to measure the airborne asbestos fibre concentration. Three years (1996-1998) of asbestos fibre count reporting are evaluated for the proficiency testing scheme organized in France to evaluate the performance of laboratories using an indirect-transfer transmission electron microscopy procedure to measure the airborne asbestos fibre concentration. Each year eight filters are distributed to each participating laboratory. These filters are obtained by filtering a suspension containing chrysotile or amphibole fibres. In 1996, 36% of the laboratories were rated 1 (the best performers; i.e. those providing counts close to the reference value). Performance improved appreciably in the last round where 85% of the laboratories were rated 1. PMID:11137700

Kauffer, E; Martine, M; Grzebyk, M; Vigneron, J C; Sandino, J P

2001-01-01

326

Scanning electron microscopy fractography analysis of fractured hollow implants.  

PubMed

Fracture of the implant is one of the possible complications affecting dental implants; it is a rare event but of great clinical relevance. The aim of the present study was to perform a scanning electron microscopy (SEM) fractography evaluation of 7 International Team for oral Implantology (ITI) hollow implants removed because of fracture. The most common clinical risk factors, such as malocclusion, bruxism, and cantilevers on the prosthesis, were absent. Seven fractured ITI hollow implants were retrieved from 5 patients and were analyzed with the use of SEM. SEM analysis showed typical signs of a cleavage-type fracture. Fractures could be due to an association of multiple factors such as fatigue, inner defects, material electrochemical problems, and tensocorrosion. PMID:20426587

Sbordone, Ludovico; Traini, Tonino; Caputi, Sergio; Scarano, Antonio; Bortolaia, Claudia; Piattelli, Adriano

2010-01-01

327

Cryo-electron microscopy of vitrified chromosomes in situ.  

PubMed Central

Chromosomes of metaphase-arrested Chinese hamster ovary (CHO) and HeLa cells were examined in situ, unfixed and unstained, by cryo-electron microscopy. In hydrated, vitrified cryo-sections, chromosomes exhibit a characteristic homogeneous, grainy texture, which, on optical diffraction, gives rise to a broad reflection corresponding to 11 nm. No superstructure or periodic order is discernible. These observations suggest that the chromosome is formed by the compact association of 11 nm filaments, or portions thereof, interacting in a manner akin to the molecules of a liquid. Some implications of the liquid model of chromosome structure are discussed. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4 and 5. Fig. 6.

McDowall, A W; Smith, J M; Dubochet, J

1986-01-01

328

Near field and exit wave computations for electron microscopy.  

PubMed

The partial wave phase shift formalism of atomic scattering is applied to compute exit wave functions for isolated Au and Si atoms under both plane wave and focused probe illumination. Connections between the far field and near field (exit) waves are clarified. This approach treats the Coulomb singularity properly though at 100keV large numbers of phase shifts are required. In principle any form of incident wave can be handled so it may provide a means for testing traditional scattering theories used in electron microscopy. By applying the analysis to an atom embedded in a constant potential rather than free space, exit spheres of radius half the interatomic spacing can be used. PMID:23726769

Howie, A

2013-05-14

329

Degradation of solar coatings observed by scanning electron microscopy  

SciTech Connect

To study the degradation of absorptive coatings used in solar energy systems and thereby aid the development of durability-related test methods for these coatings, scanning electron microscopy (SEM) studies were performed on three solar coating systems and substrates. The coating systems studied were urethane topcoat over epoxy primer on zinc phosphate-treated steel, polyvinylidene fluoride over epoxy primer on galvanized steel, and epoxy topcoat over phenolic butyrate primer on anodized aluminum. The first system was subjected to both exposure to condensing moisture and adhesion tests, the other two systems to high humidity at elevated temperature. The findings show that moisture is a primary factor affecting the durability of the coatings and that SEM is a valuable tool in studying degradation. In addition, the technique of metallographic polishing of galvanized steel with alcohol as a suspension medium is shown to produce microstructure free of metallographic defects.

Post, M.A.; Ballard, D.

1980-05-01

330

Chondrite thermal histories - Clues from electron microscopy of orthopyroxene  

NASA Astrophysics Data System (ADS)

Optically 'striated' orthopyroxenes in two ordinary chondrites, Allegan (H5) and Quenggouk (H4), are compared with shock-affected orthopyroxenes in Saint-Severin (LL6) and Ambapur Nagla (H5) by high-voltage transmission electron microscopy. The striated orthopyroxenes have very many, thin, evenly distributed lamellae of clinopyroxene. They are undeformed and also lack evidence of partial inversion from clinopyroxene to orthopyroxene. Striated orthopyroxene does not seem to be a reliable indicator of prograde metamorphism. Instead, it is interpreted as inverted protopyroxene, produced during the cooling of chondrules at slower rates than the rapid quenching of Type 3 chondrules. The conclusions are consistent with retrograde models for the evolution of H-group chondrites, in which the higher petrologic types are attributed to retarded cooling due to accretionary processes leading to the growth of the parent body.

Ashworth, J. R.

1980-01-01

331

Noise characteristics of the gas ionization cascade used in low vacuum scanning electron microscopy  

SciTech Connect

The noise characteristics of gas cascade amplified electron signals in low vacuum scanning electron microscopy (LVSEM) are described and analyzed. We derive expressions for each component contributing to the total noise culminating in a predictive, quantitative model that can be used for optimization of LVSEM operating parameters. Signal and noise behavior is characterized experimentally and used to validate the model. Under most operating conditions, the noise is dominated by the excess noise generated in the gas amplification cascade. At high gains, the excess noise increases proportionally with gain such that the signal-to-noise ratio is constant. The effects of several instrument operating parameters, including working distance, gas pressure, beam current, and detector bias, are condensed and presented in the form of a master curve.

Tileli, Vasiliki; Thiel, Bradley L. [College of Nanoscale Science and Engineering, University at Albany-SUNY, 257 Fuller Road, Albany, New York 12203 (United States); Knowles, W. Ralph; Toth, Milos [FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, Oregon 97124 (United States)

2009-07-01

332

Quantitative Lifetime Unmixing of Multiexponentially Decaying Fluorophores Using Single-Frequency Fluorescence Lifetime Imaging Microscopy  

PubMed Central

Fluorescence lifetime imaging microscopy (FLIM) is a quantitative microscopy technique for imaging nanosecond decay times of fluorophores. In the case of frequency-domain FLIM, several methods have been described to resolve the relative abundance of two fluorescent species with different fluorescence decay times. Thus far, single-frequency FLIM methods generally have been limited to quantifying two species with monoexponential decay. However, multiexponential decays are the norm rather than the exception, especially for fluorescent proteins and biological samples. Here, we describe a novel method for determining the fractional contribution in each pixel of an image of a sample containing two (multiexponentially) decaying species using single-frequency FLIM. We demonstrate that this technique allows the unmixing of binary mixtures of two spectrally identical cyan or green fluorescent proteins, each with multiexponential decay. Furthermore, because of their spectral identity, quantitative images of the relative molecular abundance of these fluorescent proteins can be generated that are independent of the microscope light path. The method is rigorously tested using samples of known composition and applied to live cell microscopy using cells expressing multiple (multiexponentially decaying) fluorescent proteins.

Kremers, Gert-Jan; van Munster, Erik B.; Goedhart, Joachim; Gadella, Theodorus W. J.

2008-01-01

333

Progress towards critical dimension low vacuum scanning electron microscopy  

NASA Astrophysics Data System (ADS)

Low vacuum scanning electron microscopy (LVSEM) is proposed and evaluated for next generation Critical Dimension (CD) metrology. Its ability to control charging artifacts and hydrocarbon contamination in order to obtain high signal-to-noise ratio, high resolution image data from insulating materials make the technology an excellent match for the increased use of high-k dielectrics and shrinking feature size in the semiconductor industry. The presence of a gas in the LVSEM chamber means that the probe characteristics and secondary electron amplification, detection, and signal-to-noise ratio differ significantly from conventional high vacuum tools. In order for low vacuum CD approaches to be viable, all of the processes must be understood and described to the degree of accuracy currently available on high vacuum systems. Consequently, the focus of this thesis is to determine an analytic form of the signal-to-noise ratio for two detector configurations: the simplified steady-state cascade system operating in the well defined Townsend's discharge region, and the high resolution, low vacuum immersion lens secondary electron detector, for which the physical amplification process has not been studied in the past. A physically realistic and ultimately predictive model, which could potentially be incorporated in CD simulation codes such as NIST's MONSEL, is developed. Its effectiveness is verified with experimental data acquired as a function of gas pressure for all important operating parameters, such as electron beam energy and current, detector bias, cascade distance, and gas type, and its capability for optimization of the imaging conditions is discussed. Noise characteristics are also analyzed using Monte Carlo gain histograms and pure statistical methods.

Tileli, Vasiliki

334

Quantitative Theory for Electron-Atom Scattering  

NASA Astrophysics Data System (ADS)

The aim of this work is to develop a general approach to electron and photon impact ionization. This approach should *be non-perturbative, *not be restricted to simple systems, *be straightforward to systematically improve, *be computationally efficient, *treat symmetric problems symmetrically. R operator formalism The concept of an R-matrix has been extended to a general coordinate hyperspace by the introduction of an R-operator, [1]. We have developed an approach to electron-atom scattering within the context of the R-operator formalism. Results will be presented for the Temkin-Poet problem [2, 3] as well as for e-H collisions. [1] R. K. Nesbet, Phys. Rev. B, 30, 4230, 1984 [2] A.Temkin, Phys. Rev. A, 126, 130, 1962 [3] R. Poet, J. Phys. B, 13,2995,1980

Whelan, Colm T.; Nesbet, Robert K.; Martinez, Jason.

2006-05-01

335

Quantitative segmentation of fluorescence microscopy images of heterogeneous tissue: Approach for tuning algorithm parameters  

NASA Astrophysics Data System (ADS)

The combination of fluorescent contrast agents with microscopy is a powerful technique to obtain real time images of tissue histology without the need for fixing, sectioning, and staining. The potential of this technology lies in the identification of robust methods for image segmentation and quantitation, particularly in heterogeneous tissues. Our solution is to apply sparse decomposition (SD) to monochrome images of fluorescently-stained microanatomy to segment and quantify distinct tissue types. The clinical utility of our approach is demonstrated by imaging excised margins in a cohort of mice after surgical resection of a sarcoma. Representative images of excised margins were used to optimize the formulation of SD and tune parameters associated with the algorithm. Our results demonstrate that SD is a robust solution that can advance vital fluorescence microscopy as a clinically significant technology.

Mueller, Jenna L.; Harmany, Zachary T.; Mito, Jeffrey K.; Kennedy, Stephanie A.; Kim, Yongbaek; Dodd, Leslie; Geradts, Joseph; Kirsch, David G.; Willett, Rebecca M.; Brown, J. Quincy; Ramanujam, Nimmi

2013-02-01

336

Influence of sample preparation and identification of subcelluar structures in quantitative holographic phase contrast microscopy  

NASA Astrophysics Data System (ADS)

Digital holographic microscopy (DHM) provides label-free quantitative phase contrast with low demands on sample preparation. Nevertheless, for DHM measurements on fixed cells the mounting medium has to be considered while the phase contrast of living cells may be influenced by the used buffer solution. To quantify these effects, the maximum cell caused phase contrast and the visibility of the nucleoli were analyzed. A second aim of the study was to identify subcellular components in DHM phase contrast images. Therefore, comparative investigations using bright field imaging, DHM and fluorescence microscopy with 4',6- Diamidino-2-phenylindol (DAPI) staining were performed. DAPI-staining visualizes cell components containing DNA. The obtained results demonstrate exemplarily for two tumor cell lines that from DHM phase contrast images of fixed cells in phosphate buffer saline (PBS) cell thickness values are obtained which are comparable to living cells. Furthermore, it is shown that in many cases nucleus components can be identified only by DHM phase contrast.

Kemper, Björn; Schmidt, Lisa; Przibilla, Sabine; Rommel, Christina; Vollmer, Angelika; Ketelhut, Steffi; Schnekenburger, Jürgen; von Bally, Gert

2010-04-01

337

Thin dielectric film thickness determination by advanced transmission electron microscopy  

SciTech Connect

High Resolution Transmission Electron Microscopy (HR-TEM) has been used as the ultimate method of thickness measurement for thin films. The appearance of phase contrast interference patterns in HR-TEM images has long been confused as the appearance of a crystal lattice by non-specialists. Relatively easy to interpret crystal lattice images are now directly observed with the introduction of annular dark field detectors for scanning TEM (STEM). With the recent development of reliable lattice image processing software that creates crystal structure images from phase contrast data, HR-TEM can also provide crystal lattice images. The resolution of both methods was steadily improved reaching now into the sub Angstrom region. Improvements in electron lens and image analysis software are increasing the spatial resolution of both methods. Optimum resolution for STEM requires that the probe beam be highly localized. In STEM, beam localization is enhanced by selection of the correct aperture. When STEM measurement is done using a highly localized probe beam, HR-TEM and STEM measurement of the thickness of silicon oxynitride films agree within experimental error. In this paper, the optimum conditions for HR-TEM and STEM measurement are discussed along with a method for repeatable film thickness determination. The impact of sample thickness is also discussed. The key result in this paper is the proposal of a reproducible method for film thickness determination.

Diebold, A.C.; Foran, B.; Kisielowski, C.; Muller, D.; Pennycook, S.; Principe, E.; Stemmer, S.

2003-09-01

338

H-pilus assembly kinetics determined by electron microscopy.  

PubMed

The kinetics of pilus outgrowth were examined for Escherichia coli containing pDT1942, a TnlacZ insertion derivative of the IncHI1 plasmid R27, which was derepressed for transfer. IncHI1 plasmids are thermosensitive for transfer. The pili specified by pDT1942 were examined by transmission electron microscopy after the pilus had been labeled with the H-pilus-specific bacteriophage Hgal, which had been inactivated with RNase A. H pili were extended by extrusion from the cell surface and not by the addition of pilin subunits to the pilus tip. After pili were removed by vortexing, the outgrowth of full-length pili (2 microns long) required 20 min. H pili expressed at the transfer optimal temperature (27 degrees C) remained stable after incubation at the transfer inhibitory temperature (37 degrees C), but the formation of mating aggregates was inhibited at 37 degrees C. Within 1 min of exposure of the host cell to a heat stimulus of 50 degrees C, pili vanished. Pili were observed in straight and flexible forms with a field emission scanning electron microscope, which may indicate a dynamic role for the pilus in conjugation. PMID:8096837

Maher, D; Sherburne, R; Taylor, D E

1993-04-01

339

Cryomesh: a new substrate for cryo-electron microscopy.  

PubMed

Here we evaluate a new grid substrate developed by ProtoChips Inc. (Raleigh, NC) for cryo-transmission electron microscopy. The new grids are fabricated from doped silicon carbide using processes adapted from the semiconductor industry. A major motivating purpose in the development of these grids was to increase the low-temperature conductivity of the substrate, a characteristic that is thought to affect the appearance of beam-induced movement (BIM) in transmission electron microscope (TEM) images of biological specimens. BIM degrades the quality of data and is especially severe when frozen biological specimens are tilted in the microscope. Our results show that this new substrate does indeed have a significant impact on reducing the appearance and severity of beam-induced movement in TEM images of tilted cryo-preserved samples. Furthermore, while we have not been able to ascertain the exact causes underlying the BIM phenomenon, we have evidence that the rigidity and flatness of these grids may play a major role in its reduction. This improvement in the reliability of imaging at tilt has a significant impact on using data collection methods such as random conical tilt or orthogonal tilt reconstruction with cryo-preserved samples. Reduction in BIM also has the potential for improving the resolution of three-dimensional cryo-reconstructions in general. PMID:20082728

Yoshioka, Craig; Carragher, Bridget; Potter, Clinton S

2010-02-01

340

Preparation of macromolecular complexes for cryo-electron microscopy  

PubMed Central

This protocol describes the preparation of frozen-hydrated single-particle specimens of macromolecular complexes. First, it describes how to create a grid surface coated with holey carbon by first inducing holes in a Formvar film to act as a template for the holey carbon that is stable under cryo-electron microscopy (cryo-EM) conditions and is sample-friendly. The protocol then describes the steps required to deposit the homogeneous sample on the grid and to plunge-freeze the grid into liquid ethane at the temperature of liquid nitrogen, so that it is suitable for cryo-EM visualization. It takes 4–5 h to make several hundred holey carbon grids and about 1 h to make the frozen-hydrated grids. The time required for sample purification varies from hours to days, depending on the sample and the specific procedure required. A companion protocol details how to collect cryo-EM data using an FEI Tecnai transmission electron microscope that can subsequently be processed to obtain a three-dimensional reconstruction of the macromolecular complex.

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

2009-01-01

341

Seeing Inside Materials by Aberration-Corrected Electron Microscopy  

SciTech Connect

The recent successful correction of lens aberrations in the electron microscope has improved resolution by more than a factor of two in just a few years, bringing many benefits for the study of materials. These benefits extend significantly beyond enhanced resolution alone. Aberration correction gives higher resolution by allowing the objective lens to have a wider aperture, which also results in a reduced depth of field. This effect can be used to only focus specific sections inside materials for the first time. In this contribution we describe recent results exploiting this capability. Additionally, we show how combining the microscopy data with first-principles theory gives new insights into materials properties. We cover two applications, both involving heavy atoms in a lighter host. The first shows how single Hf atoms can be mapped in three dimensions inside the 1 nm-wide SiO2 region of a high dielectric constant device structure, and how a link to macroscopic device properties results through theoretical calculations. The second example is from the field of nanoscience, where individual Au atoms are imaged inside Si nanowires grown by a vapor-liquid-solid mechanism. The majority of Au atoms are probably injected by the highly energetic electron beam. However, their observed sites and atomic configurations represent at least meta-stable configurations and match well to results from density functional calculations.

Pennycook, Stephen J [ORNL

2011-01-01

342

The characterization of nanoparticles using analytical electron microscopy  

NASA Astrophysics Data System (ADS)

Nanoparticles are often overlooked during routine trace evidence analyses because of their small size and the degree of difficulty needed to efficiently characterize them. However, analytical electron microscopy (AEM) enables the characterization and/or identification of nanoparticles because of its high magnification capability, the ability to gather elemental data and also the ability to determine the internal structure of a single nanoparticles(1). There is a wide variety of natural and manufactured nanoparticles that are prominent within the environment and their presence becomes very valuable in the absence of larger particles. The combustion of materials produces by-products such as nano-sized carbon soot, fumes, fly ash and gun-shot residue (GSR). Using AEM, nano-sized carbon soot, fumes, fly ash and GSR can not only be distinguished from other nanoparticles within the environment but can also be distinguished from each other because of differences in morphology, elemental composition, and internal structure. The elemental information gathered from combustion by-products during AEM analysis can also give an indication of the original source material. Other nanoparticles such as paint pigments and fillers can also be characterized by AEM using morphology, electron diffraction and elemental composition.

Hill, Whitney B.

2011-05-01

343

Application of colloidal palladium nanoparticles for labeling in electron microscopy.  

PubMed

The application of palladium nanoparticles as electron-dense markers for labeling in both transmission and scanning electron microscopy requires their conjugation to a specific protein. The conjugation protocol described here includes the dihydrolipoic acid (DHLA) capping of Pd nanoparticles (8 nm equivalent diameter) and their subsequent covalent attachment to functional protein molecules such as streptavidin, protein A, or avidin. The single-step reaction was mediated using the cross-linking agent ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC). The final Pd conjugates were fully functional, as demonstrated by labeling of ultrathin resin sections of either bovine serum albumin or secretory granules of the salivary gland isolated from the partially fed female Ixodes ricinus tick. The results of bovine serum labeling were quantified, statistically evaluated, and compared with results obtained using commercially available gold particle conjugates (10 nm diameter). The highest values of labeling density were achieved using both streptavidin-Pd (106 ± 7 particles/?m2) and protein A-Au conjugates (130 ± 18 particles/?m2) compared to a commercial streptavidin-Au (66 ± 16 particles/?m2) and protein A-Pd conjugates (70 ± 11 particles/?m2). The concentrations of both DHLA and EDC, pH during conjugation, and finally thorough washing away of unbound proteins crucially influenced conjugation. PMID:21902867

Vancová, Marie; Slouf, Miroslav; Langhans, Jan; Pavlová, Eva; Nebesá?ová, Jana

2011-09-09

344

Scanning electron microscopy in the assessment of sperm morphology.  

PubMed

The advantages of using scanning electron microscope (SEM) vis-a-vis light microscope (LM) to assess sperm morphology was studied. The semen samples obtained from 15 fertile (group I) and 25 infertile (group II) men were processed by routine procedures for LM and SEM. The usually described sperm abnormalities were identifiable with greater resolution. Sperm abnormalities were significantly more in group II, as compared with group I (P less than 0.001) by both methods. Abnormalities of different regions, like thinning of midpiece, were scored higher in SEM than in LM. The abnormality of aggregation or retraction of mitochondrial sheath was clearly visible under SEM and missed by LM. Apart from detection of certain subtle abnormalities, SEM has advantages of rapid screening, accurate quantitation directly from the screen, zooming to higher magnification and automation. PMID:2401537

Gopalkrishnan, K; Anand Kumar, T C

1990-06-01

345

Electron Microscopy Characterization of Vanadium Dioxide Thin Films and Nanoparticles  

NASA Astrophysics Data System (ADS)

Vanadium dioxide (VO_2) is a material of particular interest due to its exhibited metal to insulator phase transition at 68°C that is accompanied by an abrupt and significant change in its electronic and optical properties. Since this material can exhibit a reversible drop in resistivity of up to five orders of magnitude and a reversible drop in infrared optical transmission of up to 80%, this material holds promise in several technological applications. Solid phase crystallization of VO_2 thin films was obtained by a post-deposition annealing process of a VO_{x,x approx 2} amorphous film sputtered on an amorphous silicon dioxide (SiO_2) layer. Scanning electron microscopy (SEM) and electron-backscattered diffraction (EBSD) were utilized to study the morphology of the solid phase crystallization that resulted from this post-deposition annealing process. The annealing parameters ranged in temperature from 300°C up to 1000°C and in time from 5 minutes up to 12 hours. Depending on the annealing parameters, EBSD showed that this process yielded polycrystalline vanadium dioxide thin films, semi-continuous thin films, and films of isolated single-crystal particles. In addition to these films on SiO_2, other VO_2 thin films were deposited onto a-, c-, and r-cuts of sapphire and on TiO_2(001) heated single-crystal substrates by pulsed-laser deposition (PLD). The temperature of the substrates was kept at ˜500°C during deposition. EBSD maps and orientation imaging microscopy were used to study the epitaxy and orientation of the VO_2 grains deposited on the single crystal substrates, as well as on the amorphous SiO_2 layer. The EBSD/OIM results showed that: 1) For all the sapphire substrates analyzed, there is a predominant family of crystallographic relationships wherein the rutile VO_2{001} planes tend to lie parallel to the sapphire's {10-10} and the rutile VO_2{100} planes lie parallel to the sapphire's {1-210} and {0001}. Furthermore, while this family of relationships accounts for the majority of the VO_2 grains observed, due to the sapphire substrate's geometry there were variations within these rules that changed the orientation of VO_2 grains with respect to the substrate's normal direction. 2) For the TiO_2, a substrate with a lower lattice mismatch, we observe the expected relationship where the rutile VO_2 [100], [110], and [001] crystal directions lie parallel to the TiO_2 substrate's [100], [110], and [001] crystal directions respectively. 3) For the amorphous SiO_2 layer, all VO_2 crystals that were measurable (those that grew to the thickness of the deposited film) had a preferred orientation with the the rutile VO_2[001] crystal direction tending to lie parallel to the plane of the specimen. The use of transmission electron microscopy (TEM) is presented as a tool for further characterization studies of this material and its applications. In this work TEM diffraction patterns taken from cross-sections of particles of the a- and r-cut sapphire substrates not only solidified the predominant family mentioned, but also helped lift the ambiguity present in the rutile VO_2{100} axes. Finally, a focused-ion beam technique for preparation of cross-sectional TEM samples of metallic thin films deposited on polymer substrates is demonstrated.

Rivera, Felipe

346

Quantitative phase microscopy using dual-plane in-line digital holography.  

PubMed

We present detailed theoretical evaluation and thorough experimental investigation of quantitative phase imaging using our previously demonstrated dual-plane in-line digital holographic microscopy technique [Opt. Lett. 35, 3426 (2010)]. This evaluation is based on the recording of two interferograms at slightly different planes and numerically reconstructing the object information. The zero-order diffracted wave is eliminated by using the method of subtraction of average intensity of the entire hologram, and the twin-image diffracted wave is removed by Fourier domain processing of the two recorded holograms. Experiments are performed using controlled amplitude and phase objects and human muscle cells to demonstrate the potential of this technique. PMID:22441487

Das, Bhargab; Yelleswarapu, Chandra S; Rao, D V G L N

2012-03-20

347

Spatially resolved quantitative mapping of thermomechanical properties and phase transition temperatures using scanning probe microscopy  

DOEpatents

An approach for the thermomechanical characterization of phase transitions in polymeric materials (polyethyleneterephthalate) by band excitation acoustic force microscopy is developed. This methodology allows the independent measurement of resonance frequency, Q factor, and oscillation amplitude of a tip-surface contact area as a function of tip temperature, from which the thermal evolution of tip-surface spring constant and mechanical dissipation can be extracted. A heating protocol maintained a constant tip-surface contact area and constant contact force, thereby allowing for reproducible measurements and quantitative extraction of material properties including temperature dependence of indentation-based elastic and loss moduli.

Jesse, Stephen; Kalinin, Sergei V; Nikiforov, Maxim P

2013-07-09

348

Quantitative detection of chemical compounds in human hair with coherent anti-Stokes Raman scattering microscopy  

PubMed Central

Coherent anti-Stokes Raman scattering (CARS) microscopy is used to determine the distribution and concentration of selected compounds in intact human hair. By generating images based on ratiometric CARS contrast, quantitative concentration maps of both water and externally applied d-glycine are produced in the cortex of human hair fibers. Both water and d-glycine are found to homogeneously distribute throughout the cortical regions of the hair. The ability to selectively detect molecular agents in hair fibers is of direct relevance to understanding the chemical and physical mechanisms that underlie the performance of hair-care products.

Zimmerley, Maxwell; Lin, Chia-Yu; Oertel, David C.; Marsh, Jennifer M.; Ward, Jimmie L.; Potma, Eric Olaf

2010-01-01

349

Quantitative detection of chemical compounds in human hair with coherent anti-Stokes Raman scattering microscopy  

NASA Astrophysics Data System (ADS)

Coherent anti-Stokes Raman scattering (CARS) microscopy is used to determine the distribution and concentration of selected compounds in intact human hair. By generating images based on ratiometric CARS contrast, quantitative concentration maps of both water and externally applied d-glycine are produced in the cortex of human hair fibers. Both water and d-glycine are found to homogeneously distribute throughout the cortical regions of the hair. The ability to selectively detect molecular agents in hair fibers is of direct relevance to understanding the chemical and physical mechanisms that underlie the performance of hair-care products.

Zimmerley, Maxwell; Lin, Chia-Yu; Oertel, David C.; Marsh, Jennifer M.; Ward, Jimmie L.; Potma, Eric Olaf

2009-07-01

350

Nanoscale nuclear architecture for cancer diagnosis by spatial-domain low-coherence quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

Alterations in nuclear architecture are the hallmark diagnostic characteristic of cancer cells. In this work, we show that the nuclear architectural characteristics quantified by spatial-domain low-coherence quantitative phase microscopy (SL-QPM), is more sensitive for the identification of cancer cells than conventional cytopathology. We demonstrated the importance of nuclear architectural characteristics in both an animal model of intestinal carcinogenesis - APC/Min mouse model and human cytology specimens with colorectal cancer by identifying cancer from cytologically noncancerous appearing cells. The determination of nanoscale nuclear architecture using this simple and practical optical instrument is a significant advance towards cancer diagnosis.

Wang, Pin; Bista, Rajan K.; Khalbuss, Walid E.; Qiu, Wei; Staton, Kevin D.; Zhang, Lin; Brentnall, Teresa A.; Brand, Randall E.; Liu, Yang

2011-02-01

351

Quantitative pupil analysis in stimulated emission depletion microscopy using phase retrieval  

PubMed Central

The resolution attainable with stimulated emission depletion (STED) microscopy greatly depends on the quality of the STED laser focus. So far, visual inspection of a measured STED focus has been the only convenient means of gauging the source of aberrations. Here we describe a method, requiring no instrument modifications, for obtaining an equivalent to the complex pupil function at the back aperture of the objective and show that it provides quantitative information about aberration sources (including aberrations induced by the objective or sample). We show the accuracy of this field representation to be sufficient for reconstructing the STED focus in three dimensions and determining corrective steps.

Kromann, Emil B.; Gould, Travis J.; Juette, Manuel F.; Wilhjelm, Jens E.; Bewersdorf, Joerg

2013-01-01

352

Quantitative analysis on collagen morphology in aging skin based on multiphoton microscopy.  

PubMed

Multiphoton microscopy was employed for monitoring the structure changes of mouse dermis collagen in the intrinsic- or the extrinsic-age-related processes in vivo. The characteristics of textures in different aging skins were uncovered by fast Fourier transform in which the orientation index and bundle packing of collagen were quantitatively analyzed. Some significant differences in collagen-related changes are found in different aging skins, which can be good indicators for the statuses of aging skins. The results are valuable to the study of aging skin and also of interest to biomedical photonics. PMID:21529064

Wu, Shulian; Li, Hui; Yang, Hongqin; Zhang, Xiaoman; Li, Zhifang; Xu, Shufei

2011-04-01

353

Effects of ultramorphological changes on adhesion to lased dentin-Scanning electron microscopy and transmission electron microscopy analysis.  

PubMed

Dentin irradiation with erbium lasers has been reported to alter the composite resin bond to this treated surface. There is still a lack of studies reporting the effect of erbium lasers on dentin organic content and elucidating how laser treatment could interfere in the quality of the resin-dentin interface. This study aimed to evaluate the effect of erbium laser irradiation on dentin morphology and microtensile bond strength (?TBS) of an adhesive to dentin. Seventy-two dentin disks were divided into nine groups (n = 8): G1-Control (600-grit SiC paper); Er:YAG groups: G2- 250 mJ/4 Hz; G3- 200 mJ/4 Hz; G4- 180 mJ/10 Hz; G5- 160 mJ/10 Hz; Er,Cr:YSGG groups: G6- 2 W/20 Hz; G7- 2.5 W/20 Hz; G8- 3 W/20 Hz; G9- 4 W/20 Hz. Specimens were processed for cross-sectional analysis by scanning electron microscopy (SEM) (n = 3), transmission electron microscopy (TEM) (n = 2), and adhesive interface (n = 3). Forty-five dentin samples (n = 5) were restored and submitted to ?TBS testing. ANOVA (? = 5%) revealed that G1 presented the highest ?TBS values and irradiated groups did not differ from each other. TEM micrographs showed a superficial layer of denatured collagen fibrils. For SEM micrographs, it was possible to verify the laser effects extending to dentin subsurface presenting a rough aspect. Cross-sectional dentin micrographs of this hybridized surface revealed a pattern of modified tags with ringlike structures around it. This in vitro study showed that erbium laser irradiation interacts with the dental hard tissue resulting in a specific morphological pattern of dentin and collagen fibrils that negatively affected the bond strength to composite resin. PMID:20945461

Moretto, Simone G; Azambuja, Nilton; Arana-Chavez, Victor E; Reis, Andre F; Giannini, Marcelo; Eduardo, Carlos de P; De Freitas, Patricia M

2010-10-13

354

Self-reference extended depth-of-field quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

This paper describes a novel quantitative phase microscopy based on a simple self-referencing scheme using Michelson interferometry. In order to achieve the homogeneous reference field for accurate phase measurement, the imaging field-of-view (FOV) is split onto the sample and homogenous background areas. The reference field can be generated by rotating the relative position of the sample and homogenous background in the object arm. Furthermore, our system is realized using an extended depth-of-field (eDOF) optics, which allows quantitative phase measurement for an increase of the depth-of-field without moving objective lens or specimen. The proposed method is confirmed by experimental results using various samples such as polystyrene beads and red blood cells (RBCs).

Jang, Jaeduck; Bae, Chae Yun; Park, Je-Kyun; Ye, Jong Chul

2010-02-01

355

Quantitative surface topography determination by Nomarski reflection microscopy. 2: Microscope modification, calibration, and planar sample experiments.  

PubMed

The application of reflective Nomarski differential interference contrast microscopy for the determination of quantitative sample topography data is presented. The discussion includes a review of key theoretical results presented previously plus the experimental implementation of the concepts using a commercial Nomarski microscope. The experimental work included the modification and characterization of a commercial microscope to allow its use for obtaining quantitative sample topography data. System usage for the measurement of slopes on flat planar samples is also discussed. The discussion has been designed to provide the theoretical basis, a physical insight, and a cookbook procedure for implementation to allow these results to be of value to both those interested in the microscope theory and its practical usage in the metallography laboratory. PMID:20234540

Hartman, J S; Gordon, R L; Lessor, D L

1980-09-01

356

An open-source deconvolution software package for 3-D quantitative fluorescence microscopy imaging  

PubMed Central

Summary Deconvolution techniques have been widely used for restoring the 3-D quantitative information of an unknown specimen observed using a wide-field fluorescence microscope. Deconv, an open-source deconvolution software package, was developed for 3-D quantitative fluorescence microscopy imaging and was released under the GNU Public License. Deconv provides numerical routines for simulation of a 3-D point spread function and deconvolution routines implemented three constrained iterative deconvolution algorithms: one based on a Poisson noise model and two others based on a Gaussian noise model. These algorithms are presented and evaluated using synthetic images and experimentally obtained microscope images, and the use of the library is explained. Deconv allows users to assess the utility of these deconvolution algorithms and to determine which are suited for a particular imaging application. The design of Deconv makes it easy for deconvolution capabilities to be incorporated into existing imaging applications.

SUN, Y.; DAVIS, P.; KOSMACEK, E. A.; IANZINI, F.; MACKEY, M. A.

2010-01-01

357

Visualization of clusters in polymer electrolyte membranes by electron microscopy.  

PubMed

The morphology of ionic clusters that form in polyelectrolyte membranes has a strong effect on transport and electrical properties. In spite of considerable research effort the link between morphology and properties has not been clearly established, mainly due to difficulties in assessing nanoscale morphology. Electron microscopy (EM) has the potential to visualize morphology. However success in visualization has so far been moderate. In this review we focus on the potential of EM techniques to characterize the ionic domains. We use both experimental data and models to compare the capabilities of several EM techniques: BF TEM, HAADF, core-loss EELS, and low-loss EELS in projection imaging and STEM modes. The main problems common for all these EM modes are radiation damage and overlap of features in projection. Our models show that core loss EELS with exposures that are below the typical damage threshold is incapable of resolving 2 nm diameter sulfur-rich clusters in PEMs. While low loss EELS requires lower exposure, the insight it can provide is quite limited. HAADF and BF TEM present the most effective modes for imaging the sulfur clusters in PEMs. While BF TEM uses scattered electrons more efficiently, HAADF using slightly higher doses can provide unique information due to in-focus imaging and transparent interpretation of the images. Fortunately, in at least some interesting cases the clusters themselves are much more radiation resistant than the polymer and can be studied at exposures high enough to obtain clear images. Our simulations also show that tomographic 3D reconstruction provides the best approach for solving the overlap problem. In spite of the abilities of electron tomography, data obtained from all EM techniques improve if thin sections are studied. We briefly discuss methods for obtaining such sections. PMID:23165242

Yakovlev, Sergey; Downing, Kenneth H

2013-01-28

358

Quantitative lateral and axial flow imaging with optical coherence microscopy and tomography.  

PubMed

Optical coherence tomography (OCT) and optical coherence microscopy (OCM) allow the acquisition of quantitative three-dimensional axial flow by estimating the Doppler shift caused by moving scatterers. Measuring the velocity of red blood cells is currently the principal application of these methods. In many biological tissues, blood flow is often perpendicular to the optical axis, creating the need for a quantitative measurement of lateral flow. Previous work has shown that lateral flow can be measured from the Doppler bandwidth, albeit only for simplified optical systems. In this work, we present a generalized model to analyze the influence of relevant OCT/OCM system parameters such as light source spectrum, numerical aperture and beam geometry on the Doppler spectrum. Our analysis results in a general framework relating the mean and variance of the Doppler frequency to the axial and lateral flow velocity components. Based on this model, we present an optimized acquisition protocol and algorithm to reconstruct quantitative measurements of lateral and axial flow from the Doppler spectrum for any given OCT/OCM system. To validate this approach, Doppler spectrum analysis is employed to quantitatively measure flow in a capillary with both extended focus OCM and OCT. PMID:23938644

Bouwens, Arno; Szlag, Daniel; Szkulmowski, Maciej; Bolmont, Tristan; Wojtkowski, Maciej; Lasser, Theo

2013-07-29

359

A novel fluorescence imaging technique combining deconvolution microscopy and spectral analysis for quantitative detection of opportunistic pathogens  

SciTech Connect

A novel fluorescence imaging technique based on deconvolution microscopy and spectral analysis is presented here as an alternative to confocal laser scanning microscopy. It allowed rapid, specific and simultaneous identification of five major opportunistic pathogens, relevant for public health, in suspension and provided quantitative results.

Le Puil, Michael [Florida Gulf Coast University; Biggerstaff, John P. [University of Tennessee, Knoxville (UTK); Weidow, B. [University of Tennessee, Knoxville (UTK); Price, Jeffery R [ORNL; Naser, S. [University of Central Florida; White, D.C. [University of Tennessee, Knoxville (UTK); Alberte, R. [Florida Gulf Coast University

2006-01-01

360

Transmission electron microscopy of polymer blends and block copolymers  

NASA Astrophysics Data System (ADS)

Transmission electron microscopy (TEM) of soft matter is a field that warrants further investigation. Developments in sample preparation, imaging and spectroscopic techniques could lead to novel experiments that may further our understanding of the structure and the role structure plays in the functionality of various organic materials. Unlike most hard materials, TEM of organic molecules is limited by the amount of radiation damage the material can withstand without changing its structure. Despite this limitation, TEM has been and will be a powerful tool to study polymeric materials and other soft matter. In this dissertation, an introduction of TEM for polymer scientists is presented. The fundamentals of interactions of electrons with matter are described using the Schrodinger wave equation and scattering cross-sections to fully encompass coherent and incoherent scattering. The intensity, which is the product of the wave function and its complex conjugate, shows no perceptible change due to the sample. Instead, contrast is generated through the optical system of the microscope by removing scattered electrons or by generating interference due to material-induced phase changes. Perhaps the most challenging aspect of taking TEM images, however, is sample preparation, because TEM experiments require materials with approximately 50 nm thickness. Although ultramicrotomy is a well-established powerful tool for preparing biological and polymeric sections for TEM, the development of cryogenic Focused Ion Beam may enable unprecedented cross-sectional TEM studies of polymer thin films on arbitrary substrates with nanometer precision. Two examples of TEM experiments of polymeric materials are presented. The first involves quantifying the composition profile across a lamellar phase obtained in a multicomponent blend of saturated poly(butadiene) and poly(isobutylene), stabilized by a saturated poly(butadiene) copolymer serving as a surfactant, using TEM and self-consistent field theory (SCFT). The liquid-like nature of this system at room temperature makes traditional staining methods for the enhancement of contrast ineffective. As an alternative, we take advantage of the large inelastic scattering cross-section of soft materials to generate contrast in zero-loss TEM images. Independent spatially resolved thickness measurements enable quantification of electron scattering. This enabled a comparison between the TEM data and predictions based on SCFT without any adjustable parameters. The second example involves the utilization of energy-filtered transmission electron microscopy (EFTEM) to compute elemental maps by taking advantage of ionization events. Elemental mapping of lithium is used to determine the distribution of salt in nanostructured poly(styrene-block-ethylene oxide) (SEO) copolymer/lithium salt electrolytes. Surprisingly, the concentration of lithium within a poly(ethylene oxide) (PEO) domain is found to be inhomogeneous; the salt is localized to the middle of the channels. Self-consistent field theory simulations suggest that localization of lithium is due to chain stretching at the interface, which increases with molecular weight. EFTEM and SCFT results show that the segregation of lithium salt to the middle of the PEO lamellae is greater for higher molecular weight polymers. This is correlated with the ionic conductivity of the copolymer electrolyte, which is found to show a higher conductivity for thinner lithium lamellae.

Gomez, Enrique Daniel

361

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

SciTech Connect

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

Mueller, Knut; Rosenauer, Andreas [Institut fuer Festkoerperphysik, Universitaet Bremen, Otto-Hahn-Allee 1, 28359 Bremen (Germany); Ryll, Henning; Ordavo, Ivan; Ihle, Sebastian; Soltau, Heike [PNSensor GmbH, Roemerstrasse 28, 80803 Muenchen (Germany); Strueder, Lothar [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany); Volz, Kerstin [Materials Science Center and Faculty of Physics, Philipps Universitaet Marburg, Hans-Meerwein-Strasse, 35032 Marburg (Germany); Zweck, Josef [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetsstrasse 31, 93040 Regensburg (Germany)

2012-11-19

362

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

NASA Astrophysics Data System (ADS)

A high-speed direct electron detection system is introduced to the field of transmission electron microscopy and applied to strain measurements in semiconductor nanostructures. In particular, a focused electron probe with a diameter of 0.5 nm was scanned over a fourfold quantum layer stack with alternating compressive and tensile strain and diffracted discs have been recorded on a scintillator-free direct electron detector with a frame time of 1 ms. We show that the applied algorithms can accurately detect Bragg beam positions despite a significant point spread each 300 kV electron causes during detection on the scintillator-free camera. For millisecond exposures, we find that strain can be measured with a precision of 1.3 × 10-3, enabling, e.g., strain mapping in a 100×100 nm2 region with 0.5 nm resolution in 40 s.

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

2012-11-01

363

Karyotyping chromosomes by electron microscopy. II. A method for the sequential examination of spread and banded metaphases by light and electron microscopy  

Microsoft Academic Search

In an attempt to improve the resolving power of the conventional methods used to karyotype chromosomes, a procedure is presented here which allows the sequential study of selected R-banded metaphases by light and electron microscopy. Small sub-bands, not visible by light microscopy, could be clearly identified.

V. J. Goyanes; J. Méndez

1982-01-01

364

Atomic-Resolution 3D Electron Microscopy with Dynamic Diffraction  

SciTech Connect

Achievement of atomic-resolution electron-beam tomography will allow determination of the three-dimensional structure of nanoparticles (and other suitable specimens) at atomic resolution. Three-dimensional reconstructions will yield ''section'' images that resolve atoms overlapped in normal electron microscope images (projections), resolving lighter atoms such as oxygen in the presence of heavier atoms, and atoms that lie on non-lattice sites such as those in non-periodic defect structures. Lower-resolution electron microscope tomography has been used to produce reconstructed 3D images of nanoparticles [1] but extension to atomic resolution is considered not to be straightforward. Accurate three-dimensional reconstruction from two-dimensional projections generally requires that intensity in the series of 2-D images be a monotonic function of the specimen structure (often specimen density, but in our case atomic potential). This condition is not satisfied in electron microscopy when specimens with strong periodicity are tilted close to zone-axis orientation and produce ''anomalous'' image contrast because of strong dynamic diffraction components. Atomic-resolution reconstructions from tilt series containing zone-axis images (with their contrast enhanced by strong dynamical scattering) can be distorted when the stronger zone-axis images overwhelm images obtained in other ''random'' orientations in which atoms do not line up in neat columns. The first demonstrations of 3-D reconstruction to atomic resolution used five zone-axis images from test specimens of staurolite consisting of a mix of light and heavy atoms [2,3]. Initial resolution was to the 1.6{angstrom} Scherzer limit of a JEOL-ARM1000. Later experiments used focal-series reconstruction from 5 to 10 images to produce staurolite images from the ARM1000 with resolution extended beyond the Scherzer limit to 1.38{angstrom} [4,5]. To obtain a representation of the three-dimensional structure, images were obtained in zone-axis projections <100>, <010>, <001>, <101>, <310>, and combined to produce a three-dimensional map of Coulomb potential. Images of specimen sections are much more easily interpreted than projection images such as electron micrographs, reducing the need for techniques such as imaging at sub-Rayleigh resolution [6]. Sections through the 3D staurolite potential show atom positions as density peaks that display streaking from insufficient sampling in direction [1]. Three different specimens of perfect crystal were required to achieve the five projection directions; this makes the technique atomic-resolution electron crystallography rather than atomic-resolution tomography. Nevertheless, our results illustrate that dynamic diffraction need not be a limiting factor in atomic-resolution tomographic reconstruction. We have proposed combining ultra-high (sub-Angstrom) resolution zone-axis images with off-zone images by first using linear reconstruction of the off-zone images while excluding images obtained within a small range of tilts (of the order of 60 milliradian) of any zone-axis orientation [7], since it has been shown that dynamical effects can be mitigated by slight off-axis tilt of the specimen [8]. The (partial) reconstruction would then be used as a model for forward calculation by image simulation [9] in zone-axis directions and the structure refined iteratively to achieve satisfactory fits with the experimental zone-axis data. Another path to atomic-resolution tomography would combine ''zone-axis tomography'' with high-resolution dark-field hollow-cone (DFHC) imaging. Electron diffraction theory indicates that dynamic (multiple) scattering is much reduced under highly-convergent illumination. DFHC TEM is the analog of HAADF STEM, and imaging theory shows that image resolution can be enhanced under these conditions [10]. Images obtained in this mode could provide the initial reconstruction, with zone-axis images used for refinement [11].

O'Keefe, Michael A.; Downing, Kenneth H.; Wenk, Hans-Rudolf; Meisheng, Hu

2005-02-15

365

Transmission electron microscopy analysis of corroded metal waste forms.  

SciTech Connect

This report documents the results of analyses with transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (ED) of samples of metallic waste form (MWF) materials that had been subjected to various corrosion tests. The objective of the TEM analyses was to characterize the composition and microstructure of surface alteration products which, when combined with other test results, can be used to determine the matrix corrosion mechanism. The examination of test samples generated over several years has resulted in refinements to the TEM sample preparation methods developed to preserve the orientation of surface alteration layers and the underlying base metal. The preservation of microstructural spatial relationships provides valuable insight for determining the matrix corrosion mechanism and for developing models to calculate radionuclide release in repository performance models. The TEM results presented in this report show that oxide layers are formed over the exposed steel and intermetallic phases of the MWF during corrosion in aqueous solutions and humid air at elevated temperatures. An amorphous non-stoichiometric ZrO{sub 2} layer forms at the exposed surfaces of the intermetallic phases, and several nonstoichiometric Fe-O layers form over the steel phases in the MWF. These oxide layers adhere strongly to the underlying metal, and may be overlain by one or more crystalline Fe-O phases that probably precipitated from solution. The layer compositions are consistent with a corrosion mechanism of oxidative dissolution of the steel and intermetallic phases. The layers formed on the steel and intermetallic phases form a continuous layer over the exposed waste form, although vertical splits in the layer and corrosion in pits and crevices were seen in some samples. Additional tests and analyses are needed to verify that these layers passivate the underlying metals and if passivation can break down as the MWF corrodes. The importance of localized corrosion should also be determined.

Dietz, N. L.

2005-04-15

366

Activated sludge characterization through microscopy: A review on quantitative image analysis and chemometric techniques.  

PubMed

In wastewater treatment processes, and particularly in activated sludge systems, efficiency is quite dependent on the operating conditions, and a number of problems may arise due to sludge structure and proliferation of specific microorganisms. In fact, bacterial communities and protozoa identification by microscopy inspection is already routinely employed in a considerable number of cases. Furthermore, quantitative image analysis techniques have been increasingly used throughout the years for the assessment of aggregates and filamentous bacteria properties. These procedures are able to provide an ever growing amount of data for wastewater treatment processes in which chemometric techniques can be a valuable tool. However, the determination of microbial communities' properties remains a current challenge in spite of the great diversity of microscopy techniques applied. In this review, activated sludge characterization is discussed highlighting the aggregates structure and filamentous bacteria determination by image analysis on bright-field, phase-contrast, and fluorescence microscopy. An in-depth analysis is performed to summarize the many new findings that have been obtained, and future developments for these biological processes are further discussed. PMID:24176501

Mesquita, Daniela P; Amaral, A Luís; Ferreira, Eugénio C

2013-09-16

367

Quantitative visualization of colloidal and intracellular gold nanoparticles by confocal microscopy.  

PubMed

Gold nanoparticles (AuNPs) have the potential to become a versatile biomarker. For further use of AuNPs labeled with functionalized molecules, their visualization in biological systems by routine laboratory tools such as light microscopy is crucial. However, the size far below the diffraction limit affords specialized parameters for microscopical detection, which stimulated the current study, aimed to determine from which size onward AuNPs, either in dispersion or cell-associated, can be reliably detected by standard confocal microscopy. First, gold colloids of size-restricted fractions are examined in dispersion. At a minimum particle size of 60 nm, detection appears to be reliable. Particle counts in dilution series confirm these results by revealing single particle detection of 60-nm colloids. Second, AuNPs are visualized and quantified in cells, which interestingly cause a phase shift in the reflection of AuNPs. Gold mass spectroscopy confirms the number of AuNPs counted microscopically inside cells. Furthermore, it demonstrates for the first time a very high diffusion rate of 15-nm particles into the cells. In conclusion, the results back the suitability of confocal microscopy for the quantitative tracking of colloidal and intracellular gold nanoparticles sized 60 nm. PMID:20615017

Klein, Sabine; Petersen, Svea; Taylor, Ulrike; Rath, Detlef; Barcikowski, Stephan

368

Accurate construction of photoactivated localization microscopy (PALM) images for quantitative measurements.  

PubMed

Localization-based superresolution microscopy techniques such as Photoactivated Localization Microscopy (PALM) and Stochastic Optical Reconstruction Microscopy (STORM) have allowed investigations of cellular structures with unprecedented optical resolutions. One major obstacle to interpreting superresolution images, however, is the overcounting of molecule numbers caused by fluorophore photoblinking. Using both experimental and simulated images, we determined the effects of photoblinking on the accurate reconstruction of superresolution images and on quantitative measurements of structural dimension and molecule density made from those images. We found that structural dimension and relative density measurements can be made reliably from images that contain photoblinking-related overcounting, but accurate absolute density measurements, and consequently faithful representations of molecule counts and positions in cellular structures, require the application of a clustering algorithm to group localizations that originate from the same molecule. We analyzed how applying a simple algorithm with different clustering thresholds (t(Thresh) and d(Thresh)) affects the accuracy of reconstructed images, and developed an easy method to select optimal thresholds. We also identified an empirical criterion to evaluate whether an imaging condition is appropriate for accurate superresolution image reconstruction with the clustering algorithm. Both the threshold selection method and imaging condition criterion are easy to implement within existing PALM clustering algorithms and experimental conditions. The main advantage of our method is that it generates a superresolution image and molecule position list that faithfully represents molecule counts and positions within a cellular structure, rather than only summarizing structural properties into ensemble parameters. This feature makes it particularly useful for cellular structures of heterogeneous densities and irregular geometries, and allows a variety of quantitative measurements tailored to specific needs of different biological systems. PMID:23251611

Coltharp, Carla; Kessler, Rene P; Xiao, Jie

2012-12-12

369

Accurate Construction of Photoactivated Localization Microscopy (PALM) Images for Quantitative Measurements  

PubMed Central

Localization-based superresolution microscopy techniques such as Photoactivated Localization Microscopy (PALM) and Stochastic Optical Reconstruction Microscopy (STORM) have allowed investigations of cellular structures with unprecedented optical resolutions. One major obstacle to interpreting superresolution images, however, is the overcounting of molecule numbers caused by fluorophore photoblinking. Using both experimental and simulated images, we determined the effects of photoblinking on the accurate reconstruction of superresolution images and on quantitative measurements of structural dimension and molecule density made from those images. We found that structural dimension and relative density measurements can be made reliably from images that contain photoblinking-related overcounting, but accurate absolute density measurements, and consequently faithful representations of molecule counts and positions in cellular structures, require the application of a clustering algorithm to group localizations that originate from the same molecule. We analyzed how applying a simple algorithm with different clustering thresholds (tThresh and dThresh) affects the accuracy of reconstructed images, and developed an easy method to select optimal thresholds. We also identified an empirical criterion to evaluate whether an imaging condition is appropriate for accurate superresolution image reconstruction with the clustering algorithm. Both the threshold selection method and imaging condition criterion are easy to implement within existing PALM clustering algorithms and experimental conditions. The main advantage of our method is that it generates a superresolution image and molecule position list that faithfully represents molecule counts and positions within a cellular structure, rather than only summarizing structural properties into ensemble parameters. This feature makes it particularly useful for cellular structures of heterogeneous densities and irregular geometries, and allows a variety of quantitative measurements tailored to specific needs of different biological systems.

Coltharp, Carla; Kessler, Rene P.; Xiao, Jie

2012-01-01

370

TRANSMISSION ELECTRON MICROSCOPY STUDY OF HELIUM BEARING FUSION WELDS  

SciTech Connect

A transmission electron microscopy (TEM) study was conducted to characterize the helium bubble distributions in tritium-charged-and-aged 304L and 21Cr-6Ni-9Mn stainless steel fusion welds containing approximately 150 appm helium-3. TEM foils were prepared from C-shaped fracture toughness test specimens containing {delta} ferrite levels ranging from 4 to 33 volume percent. The weld microstructures in the low ferrite welds consisted mostly of austenite and discontinuous, skeletal {delta} ferrite. In welds with higher levels of {delta} ferrite, the ferrite was more continuous and, in some areas of the 33 volume percent sample, was the matrix/majority phase. The helium bubble microstructures observed were similar in all samples. Bubbles were found in the austenite but not in the {delta} ferrite. In the austenite, bubbles had nucleated homogeneously in the grain interiors and heterogeneously on dislocations. Bubbles were not found on any austenite/austenite grain boundaries or at the austenite/{delta} ferrite interphase interfaces. Bubbles were not observed in the {delta} ferrite because of the combined effects of the low solubility and rapid diffusion of tritium through the {delta} ferrite which limited the amount of helium present to form visible bubbles.

Tosten, M; Michael Morgan, M

2008-12-12

371

Reference nano-dimensional metrology by scanning transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Traceable and accurate reference dimensional metrology of nano-structures by scanning transmission electron microscopy (STEM) is introduced in the paper. Two methods, one based on the crystal lattice constant and the other based on the pitch of a feature pair, were applied to calibrate the TEM magnification. The threshold value, which was defined as the half-intensity of boundary materials, is suggested to extract the boundary position of features from the TEM image. Experimental investigations have demonstrated the high potential of the proposed methods. For instance, the standard deviation from ten repeated measurements of a line structure with a nominal 100 nm critical dimension (CD) reaches 1? = 0.023 nm, about 0.02%. By intentionally introduced defocus and larger sample alignment errors, the investigation shows that these influences may reach 0.20 and 1.3 nm, respectively, indicating the importance of high-quality TEM measurements. Finally, a strategy for disseminating the destructive TEM results is introduced. Using this strategy, the CD of a reference material has been accurately determined. Its agreement over five independent TEM measurements is below 1.2 nm.

Dai, Gaoliang; Heidelmann, Markus; Kübel, Christian; Prang, Robby; Fluegge, Jens; Bosse, Harald

2013-08-01

372

Light and transmission electron microscopy of immature camelus dromedarius oocyte.  

PubMed

In order to provide a consistent system for laboratory production of embryos, the characteristics of immature camel oocyte must first be described. The objective of this study was to define ultrastructural features of immature camel oocyte. Ovaries were obtained from camels at a local abattoir, and then transported to the laboratory within 2 h. Camelus cumulus oocyte complexes (COCs) were aspirated from 2-6 mm follicles using a 22-gauge needle. Excellent and good quality COCs were selected and prepared for transmission electron microscopy study using a cavity slide. The fine structure of camel oocyte is morphologically similar to that of other mammalian oocytes. However, some minor differences exist between COC of camel and other mammalian species. Different size and shape of membrane-bound vesicles, lipid droplet, mitochondria and cortical granules were distributed throughout the ooplasm. Discrete or in association with endoplasmic reticulum, Golgi complexes were observed in the periphery of the oocytes. The majority of the oocytes were in the germinal vesicle stage. PMID:15239809

Nili, H; Mesbah, F; Kafi, M; Nasr Esfahani, M H

2004-08-01

373

Scanning electron microscopy applied to seed-borne fungi examination.  

PubMed

The aim of this study was to test the standard scanning electron microscopy (SEM) as a potential alternative to study seed-borne fungi in seeds, by two different conditions of blotter test and water restriction treatment. In the blotter test, seeds were subjected to conditions that enabled pathogen growth and expression, whereas the water restriction method consisted in preventing seed germination during the incubation period, resulting in the artificial inoculation of fungi. In the first condition, seeds of common bean (Phaseolus vulgaris L.), maize (Zea mays L.), and cotton (Gossypium hirsutum L.) were submitted to the standard blotter test and then prepared and observed with SEM. In the second condition, seeds of cotton (G. hirsutum), soybean (Glycine max L.), and common bean (P. vulgaris L.) were, respectively, inoculated with Colletotrichum gossypii var. cephalosporioides, Colletotrichum truncatum, and Colletotrichum lindemuthianum by the water restriction technique, followed by preparation and observation with SEM. The standard SEM methodology was adopted to prepare the specimens. Considering the seeds submitted to the blotter test, it was possible to identify Fusarium sp. on maize, C. gossypii var. cephalosporioides, and Fusarium oxysporum on cotton, Aspergillus flavus, Penicillium sp., Rhizopus sp., and Mucor sp. on common bean. Structures of C. gossypii var. cephalosporioides, C. truncatum, and C. lindemuthianum were observed in the surface of inoculated seeds. PMID:19204924

Alves, Marcelo de Carvalho; Pozza, Edson Ampélio

2009-07-01

374

Microstructural Analysis of Ferroelectric Oxides by Electron Microscopy  

NASA Astrophysics Data System (ADS)

We have investigated nanoscaled domain configuration of Pb(Ti1-xZrx)O3 (PTZ) and (1-x)Pb(Mg1/3Nb2/3)O3- xPbTiO3 ((1-x)PMN-xPT) in the monoclinic phase around a morphotropic phase boundary (MPB) region thoroughly by means of a transmission electron microscopy (TEM), in order to clarify mechanism of the enhancement of the piezoelectric effect. Two types of domain structures with inhomogeneous configuration were found around the MPB region. One is domain structures characterized by the formation of the nanoscaled herringbone-type domain structures with the ~10 nm width inside the macroscopic-sized banded domains with the 100~200 nm width. The other is as an aggregation of nanoscaled domains with the average size of about 10 nm. An in-situ TEM observation revealed that these nanoscaled domain structures are inherent to the monoclinic phase, which should be responsible for the excellent piezoelecrtric response.

Mori, Shigeo; Koyama, Yasumasa

375

Ultradeep, ultramafic mantle xenoliths: transmission electron microscopy preliminary results  

NASA Astrophysics Data System (ADS)

The defect microstructure of ultradeep garnets from the Jagersfontein kimberlite pipe (South Africa) was investigated by transmission electron microscopy. These crystals exhibit a high density of dislocations, most of which form well-organized and regularly spaced subgrain boundaries. Free dislocations are also detected; most of them have a Burgers vector 1/2<111> (shortest lattice repeat), but a few <100> Burgers vectors are also characterized, especially in junctions. Small needle-shaped pyroxene exsolutions are also detected. They exsolved from the Si-rich garnets during assent to the Earth's surface. Their nucleation and growth required bulk diffusion, and this process may have affected the original dislocation microstructure. It is believed, however, that the observed dislocation pattern still reflects the original deformation regime of garnets at very high pressure and temperature and this dislocation pattern strongly suggests that garnets were highly ductile. Finally, a number of precipitates of a dense amorphous phase of pure carbon are also detected. They might result from the amorphization of small diamonds exsolved from the garnet as the pressure was progressively released.

Doukhan, N.; Sautter, V.; Doukhan, J. C.

1994-03-01

376

Transcription mapping of the Escherichia coli chromosome by electron microscopy.  

PubMed Central

The distinctive double Christmas tree morphology of rRNA operons as visualized by electron microscopy makes them easy to recognize in chromatin spreads from Escherichia coli. On the basis of the pattern of nascent transcripts on nearby transcription units and the relative distances of the operons from one another and the replication origin, we are now able to specifically identify five of the seven rRNA operons in E. coli. The use of rRNA operons as markers of both position and distance has resulted in the morphological mapping of a significant portion of the E. coli chromosome; over 600 kilobase pairs in the 84- to 90-min and 72-min regions can now be recognized. Since individual rRNA operons could be identified, direct comparisons could be made of their transcriptional activities. As judged by the densities of RNA polymerases along the operons, rrnA, rrnB, rrnC, rrnD, and rrnE were all transcribed at similar levels, with one RNA polymerase every 85 base pairs. The ability to recognize individual operons and specific regions of the chromosome allows direct comparisons of various genetic parameters. Images

French, S L; Miller, O L

1989-01-01

377

Applications of Direct Detection Device in Transmission Electron Microscopy  

PubMed Central

A prototype Direct Detection Device (DDD) camera system has shown great promise in improving both the spatial resolution and the signal to noise ratio for electron microscopy at 120–400 keV beam energies (Xuong, et al., 2007. Methods in Cell Biology, 79, 721–739). Without the need for a resolution-limiting scintillation screen as in the charge coupled device (CCD), the DDD camera can outperform CCD based systems in terms of spatial resolution, due to its small pixel size (5 ?m). In this paper, the modulation transfer function (MTF) of the DDD prototype is measured and compared with the specifications of commercial scientific CCD camera systems. Combining the fast speed of the DDD with image mosaic techniques, fast wide-area imaging is now possible. In this paper, the first large area mosaic image and the first tomography dataset from the DDD camera are presented, along with an image processing algorithm to correct the specimen drift utilizing the fast readout of the DDD system.

Jin, Liang; Milazzo, Anna-Clare; Kleinfelder, Stuart; Li, Shengdong; Leblanc, Philippe; Duttweiler, Fred; Bouwer, James C.; Peltier, Steven T.; Ellisman, Mark H.; Xuong, Nguyen-Huu

2008-01-01

378

Visualization of neural cell adhesion molecule by electron microscopy  

PubMed Central

The 130- and 160-kD polypeptide forms of the neural cell adhesion molecule (NCAM) were analyzed by electron microscopy after low angle rotary shadowing and freeze replication. Individual NCAM molecules appeared as uniformly thick rods, with a distinct bend or hinge region near their middle. Aggregates were also present, containing two to six rods in a pinwheel-like configuration without measurable overlap between rods. The 130- and 160-kD NCAM forms had lengths of 38 and 51 nm, respectively, with a difference in arm length distal to the bend, but not toward the center of the pinwheel. Although enzymatic removal of the polysialic acid moiety on NCAM did not alter the appearance of individual molecules, it did increase the average number of arms per aggregate. Monoclonal antibodies that recognize defined regions of the NCAM polypeptide were used to provide landmarks on the observed molecular figures. Two antibodies specific for cytoplasmic epitopes near the COOH terminus were clustered at the distal tip of aggregated arms. Two other antibodies that react with epitopes near the NH2 terminus and the middle of the molecule bound to sites more centrally located on the pinwheel structure. Together, these results suggest that the observed aggregates represent an association of molecules near their NH2-terminal homophilic binding site, and have led to several predictions about the nature of an NCAM-mediated cell-cell bond.

1987-01-01

379

Electron microscopy in the diagnosis of pituitary tumors.  

PubMed

The usefulness and limitations of electron microscopy (EM) in pituitary tumor diagnosis are reviewed and illustrated with clinical examples. The traditional classification of chromophil and chromophobe adenomas is often inconsistent with the hormonal activity of the tumors. Virtually all pituitary adenomas contain some secretory granules when viewed with EM. Endocrine inactive chromophobe adenomas contain 150 nm granules with no demonstrable hormone function. Typical growth hormone (GH) secreting eosinophil adenomas contain large 375 nm granules which dominate the cell cytoplasm. GH secreting chromophobic tumors contain secretory granules of abnormal size and concentration which are invisible to the light microscopist. The variability in granule size may indicate the production of abnormal granules or reflect the stage of the cell in a secretory cycle. Because of this wide range in granule size, the identification of tumor cell type or hormone produced is not reliable by granule measurement alone. Some neoplasms in the sella turcica may be so bizzare or undifferentiated as to defy classification. In such instances, EM can reveal ultrastructural details which identify their origin from pituitary tissue. Malignant pituitary tumors may contain minute secretory granules, and rare pituitary oncocytomas are packed with abnormal mitochondria. PMID:485091

Farmer, P M

380

High resolution quantitative phase imaging in digital holographic microscopy by modulated object illumination with an electrically focusable lens  

NASA Astrophysics Data System (ADS)

In digital holographic microscopy (DHM), scattering patterns that are induced by coherent laser light affect the resolution for the detection of optical path length changes. We present a simple and efficient approach for the reduction of coherent disturbances in quantitative phase imaging in self-interference DHM that is based on amplitude and phase modulation of the sample illumination. The performance of the method for quantitative phase imaging is characterized and the application for quantitative analysis of living cells is illustrated.

Kemper, Björn; Schubert, Robin; Vollmer, Angelika

2013-06-01

381

Electron Tunneling: Inelastic Electron Tunneling Spectroscopy and Low Temperature Scanning Tunneling Microscopy  

Microsoft Academic Search

This thesis describes experiments encompassing both Inelastic Electron Tunneling Spectroscopy (IETS) and Scanning Tunneling Microscopy (STM). IETS is used to study the tunneling characteristics of undoped Mg-MgO-metal tunnel junctions. The development of a low temperature STM, and it's use to study high T_{rm c} superconductors is discussed. The IETS experiments indicate the tunneling characteristics can be improved by increasing the

Mark Gallagher

1990-01-01

382

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

SciTech Connect

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

Rykaczewski, K.; Scott, J. H. J. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Fedorov, A. G. [G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2011-02-28

383

New electron microscopy techniques of the study of meteoritic metal.  

SciTech Connect

Metallic Phases in extraterrestrial materials are composed of Fe-Ni with minor amounts of Co, P, Si, Cr, etc. Electron microscopy techniques (SEM, TEM, EPMA, AEM) have been used for almost 50 years to study micron and submicron microscopic features in the metal phases (Fig. 1) such as clear taenite, cloudy zone, plessite, etc [1,2]. However lack of instrumentation to prepare TEM thin foils in specific sample locations and to obtain micro-scale crystallographic data have limited these investigations. New techniques such as the focused ion beam (FIB) and the electron backscatter electron diffraction (EBSD) techniques have overcome these limitations. The application of the FIB instrument has allowed us to prepare {approx}10 um long by {approx} 5um deep TEM thin sections of metal phases from specific regions of metal particles, in chondrites, irons and stony iron meteorites, identified by optical and SEM observation. Using a FEI dual beam FIB we were able to study very small metal particles in samples of CH chondrites [3] and zoneless plessite (ZP) in ordinary chondrites. Fig. 2 shows a SEM photomicrograph of a {approx}40 um ZP particle in Kernouve, a H6 chondrite. Fig. 3a,b shows a TEM photograph of a section of the FIB prepared TEM foil of the ZP particle and a Ni trace through a tetrataenite/kamacite region of the particle. It has been proposed that the Widmanstatten pattern in low P iron meteorites forms by martensite decomposition, via the reaction {gamma} {yields} {alpha}{sub 2} + {gamma} {yields} {alpha} + {gamma} in which {alpha}{sub 2}, martensite, decomposes to the equilibrium {alpha} and {gamma} phases during the cooling process [4]. In order to show if this mechanism for Widmanstatten pattern formation is correct, crystallographic information is needed from the {gamma} or taenite phases throughout a given meteorite. The EBSD technique was employed in this study to obtain the orientation of the taenite surrounding the initial martensite phase and the kamacite which forms as {alpha}{sub 2} or as Widmanstatten plates in a series of IVB irons. Fig. 4a,b shows EBSD orientation maps of taenite and kamacite from the Tawallah Valley IVB iron. We observe that the orientation of the taenite in the IVB meteorites is the same throughout the sample consistent with the orientation of the high temperature single phase taenite before formation of the Widmanstatten pattern.

Michael, Joseph Richard; Goldstein, Joseph I. (University of Massachusetts, Amherst, MA); Kotula, Paul Gabriel; Jones, R. H. (University of New Mexico, Albuquerque, NM.)

2005-02-01

384

Visualization and Quantitative Analysis of Reconstituted Tight Junctions Using Localization Microscopy  

PubMed Central

Tight Junctions (TJ) regulate paracellular permeability of tissue barriers. Claudins (Cld) form the backbone of TJ-strands. Pore-forming claudins determine the permeability for ions, whereas that for solutes and macromolecules is assumed to be crucially restricted by the strand morphology (i.e., density, branching and continuity). To investigate determinants of the morphology of TJ-strands we established a novel approach using localization microscopy. TJ-strands were reconstituted by stable transfection of HEK293 cells with the barrier-forming Cld3 or Cld5. Strands were investigated at cell-cell contacts by Spectral Position Determination Microscopy (SPDM), a method of localization microscopy using standard fluorophores. Extended TJ-networks of Cld3-YFP and Cld5-YFP were observed. For each network, 200,000 to 1,100,000 individual molecules were detected with a mean localization accuracy of ?20 nm, yielding a mean structural resolution of ?50 nm. Compared to conventional fluorescence microscopy, this strongly improved the visualization of strand networks and enabled quantitative morphometric analysis. Two populations of elliptic meshes (mean diameter <100 nm and 300–600 nm, respectively) were revealed. For Cld5 the two populations were more separated than for Cld3. Discrimination of non-polymeric molecules and molecules within polymeric strands was achieved. For both subtypes of claudins the mean density of detected molecules was similar and estimated to be ?24 times higher within the strands than outside the strands. The morphometry and single molecule information provided advances the mechanistic analysis of paracellular barriers. Applying this novel method to different TJ-proteins is expected to significantly improve the understanding of TJ on the molecular level.

Kaufmann, Rainer; Piontek, Jorg; Grull, Frederik; Kirchgessner, Manfred; Rossa, Jan; Wolburg, Hartwig; Blasig, Ingolf E.; Cremer, Christoph

2012-01-01

385

Nucleation and growth of cobalt disilicide precipitates during in-situ transmission electron microscopy implantation.  

SciTech Connect

The paper is aimed at getting deeper insight into the fundamental mechanisms that govern CoSi{sub 2} precipitate nucleation and growth during Co ion implantation at high temperatures (500-650 C). Information about nucleation and growth of metal silicides as a function of temperature and implantation flux is provided by experiments on cobalt implantation in silicon, performed directly by in situ transmission electron microscopy. The main attention is paid to the nucleation of B-type precipitates, which dominate under ion implantation conditions. The obtained quantitative behavior of precipitate number density and size and the scaling of these values with implantation flux are discussed and rationalized in terms of analytical and simulation approaches. An atomistic model of B-type precipitate nucleation based on the first-principles calculations of relative energetic efficiency of different Co clusters is proposed.

Ruault, M.-O.; Fortuna, F.; Borodin, V. A.; Ganchenkova, M. G.; Kirk, M. A.; CSNSM; RRC Kurchatov Inst.; Helsinki Univ. Technology

2008-01-01

386

Calculated Sputtering and Atomic Displacement Cross-Sections for Applications to Medium Voltage Analytical Electron Microscopy.  

National Technical Information Service (NTIS)

The development of medium voltage electron microscopes having high brightness electron sources and ultra-high vacuum environments has been anticipated by the microscopy community now for several years. The advantages of such a configuration have been disc...

C. R. Bradley N. J. Zaluzec

1987-01-01

387

A correlative light and electron microscopy method based on laser micropatterning and etching.  

PubMed

Correlative microscopy is a hybrid method that allows the localization of events observed under visible, ultraviolet, or infrared light, at molecular and submolecular levels, combining two microscopy techniques. However, the main limitation of correlative microscopy is to develop a labeling technique that can be easily used first in light and then in electron microscopy. Laser etching is a well-established method to create precisely designed shapes or volumes in various materials including glass. We have applied this technique to develop a new correlative light and electron microscopy method and to apply it in our study of the Golgi apparatus. The location of the cell of interest is laser-inscribed into the glass allowing a simple follow-up in light and fluorescence microscopy. Furthermore, the glass surface is laser-etched and upon fixation and flat embedding, the inverse ridge can be localized as well as the cell of interest, which is then processed for electron microscopy. PMID:19066029

Colombelli, Julien; Tängemo, Carolina; Haselman, Uta; Antony, Claude; Stelzer, Ernst H K; Pepperkok, Rainer; Reynaud, Emmanuel G

2008-01-01

388

Electron microscopy and in situ testing of mechanical deformation of carbon nanotubes.  

PubMed

In this paper, the electron diffraction technique to determine the helicity and atomic structure of carbon nanotubes is reviewed, as well as different mechanical test methods, tensile test, bending test, compression test and vibration test of carbon nanotubes by in situ electron microscopy are summarized while the relationship between mechanical properties and structures revealed by experiments is addressed. Except for these, the electric current and electron beam irradiation effect and some other novel electron microscopy experiments are also incorporated. PMID:21592802

Zhao, Jiong; Zhu, Jing

2011-04-21

389

Comparison of Scheimpflug-photography, specular microscopy and scanning electron microscopy to detect corneal changes in toxicity studies in rats  

SciTech Connect

With an increasing number of in-vivo methods to examine the eyes of laboratory animals, the rat has become an important animal model in experimental eye research. Specular microscopy is a clinical tool to examine the corneal endothelium in-vivo. To evaluate the versatility of this method for small animal eyes, we studied both corneal endothelial cell-count and corneal thickness in normal rats as well as those with diabetic, naphthalene and UV-B cataract. As a reference scanning electron microscopy (SEM) of the corneal endothelium was performed. For cell-counts the correlation coefficient between both methods was found to be sufficient. The comparison of corneal thickness measurement (SEM-values) with specular microscopy and with Scheimpflugbiometry failed to show a satisfactory correlation. The study proves that specular microscopy is a useful tool to document changes also in the endothelium of the rat-cornea.

Boeker, T.W.; Wegener, A.; Koch, F.; Hockwin, O. (University-Eye-Clinic Bonn (Germany))

1990-01-01

390

PREFACE: Electron Microscopy and Analysis Group Conference 2009  

NASA Astrophysics Data System (ADS)

The latest biennial conference of the Electron Microscopy and Analysis Group (EMAG) of the Institute of Physics was held at the University of Sheffield on 9-11 September, 2009. In addition, the Advanced School associated with the conference was run at the University of Sheffield on 8 September. It was particularly pleasing to return to Sheffield after ten years, the successful and memorable EMAG 99 having been held here too. The subject areas covered at EMAG 2009 were advanced electron microscopy techniques; investigating structure-property relationships in advanced materials; nanophysics and nanotechnology. The EMAG 2009 conference attracted 172 delegates while the Advanced School had a full complement of eighteen attendees. Three plenary lectures were given to the whole conference and invited contributions were presented within the theme of each of nine parallel sessions. There were 54 contributed oral presentations within these parallel Sessions and a further 89 poster presentations. All authors were invited to contribute a paper to this Proceedings volume and 108 papers are presented here. I thank all who presented at EMAG 2009 and those who provided a paper for this Proceedings. Each paper was peer reviewed by two reviewers and I also want to thank those colleagues who helped with this essential task. In this volume, the plenary papers are presented first followed by all papers presented in each themed session. These sessions are ordered alphabetically. Within each Session, the invited presentations are presented first, followed by oral and poster contributions together. Another activity of EMAG which is directed primarily at less experienced scientists is the Advanced School. This year, this was on Nanofabrication and Nanomanipulation and I want to thank Guenter Moebus and his colleagues at th University of Sheffield for putting on such an excellent Advanced School. The EMAG series of conferences are well-known not only for the academic conference but also for the major trade exhibition which runs in parallel. This requires a great deal of additional planning and effort on the part of the conference department of the IoP but particularly by representatives of the exhibiting companies. This year there were 29 exhibitors, several of whom brought major items of equipment to demonstrate to delegates. Here I want to thank all the exhibitors, Jill Cowlard and Nicola Deedman of CEM and Pete Lander of JEOL for their efforts in making the trade exhibition such a success. Finally, sincere thanks to the other members of the EMAG committee, especially Pete Nellist for his work on the scientific programme, and Guenter Moebus, Thomas Walther and colleagues for their invaluable work 'on the ground' at Sheffield, and also to Claire Garland and Lisa Cornwell at IoP for all their hard work and for keeping the academics under control! Richard Baker University of St Andrews EMAG Chair and EMAG 2009 Proceedings Editor Session Editors Richard Brydson Stephen Donnelly Ian MacLaren David McComb Günter Möbus Peter Nellist Dogan Ozkaya Thomas Walther

Baker, Richard

2010-04-01

391

Comparative determination of the {alpha}/{beta} phase fraction in {alpha}+{beta}-titanium alloys using X-ray diffraction and electron microscopy  

SciTech Connect

A comparison is made between the measured {alpha}/{beta} phase fractions in Ti-6246 using X-ray diffraction (XRD) and electron microscopy. Image analysis of SEM and TEM images was compared to the phase fraction estimate obtained using electron backscattered diffraction, lab and high-energy synchrotron XRD. There was a good agreement between the electron microscopic and diffraction techniques, provided that the microstructural parameters of grain size and texture are estimated correctly when using quantitative Rietveld refinement.

Attallah, M.M., E-mail: moataz.attallah@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor St., Manchester, M1 7HS (United Kingdom); Zabeen, S., E-mail: suraiya.zabeen@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor St., Manchester, M1 7HS (United Kingdom); Cernik, R.J., E-mail: b.cernik@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor St., Manchester, M1 7HS (United Kingdom); Preuss, M., E-mail: michael.preuss@manchester.ac.uk [School of Materials, University of Manchester, Grosvenor St., Manchester, M1 7HS (United Kingdom)

2009-11-15

392

Hierarchical level features based trainable segmentation for electron microscopy images  

PubMed Central

Background The neuronal electron microscopy images segmentation is the basic and key step to efficiently build the 3D brain structure and connectivity for a better understanding of central neural system. However, due to the visual complex appearance of neuronal structures, it is challenging to automatically segment membranes from the EM images. Methods In this paper, we present a fast, efficient segmentation method for neuronal EM images that utilizes hierarchical level features based on supervised learning. Hierarchical level features are designed by combining pixel and superpixel information to describe the EM image. For pixels in a superpixel have similar characteristics, only part of them is automatically selected and used to reduce information redundancy. To each selected pixel, 34 dimensional features are extracted by traditional way. Each superpixel itself is viewed as a unit to extract 35 dimensional features with statistical method. Also, 3 dimensional context level features among multi superpixels are extracted. Above three kinds of features are combined as a feature vector, namely, hierarchical level features to use for segmentation. Random forest is used as classifier and is trained with hierarchical level features to perform segmentation. Results In small sample condition and with low-dimensional features, the effectiveness of our method is verified on the data set of ISBI2012 EM Segmentation Challenge, and its rand error, warping error and pixel error attain to 0.106308715, 0.001200104 and 0.079132453, respectively. Conclusions Comparing to pixel level or superpixel level features, hierarchical level features have better discrimination ability and the proposed method is promising for membrane segmentation.

2013-01-01

393

Environmental scanning electron microscopy observation of the ultrastructure of Demodex.  

PubMed

In this study, numbers of Demodex of hair follicles and sebaceous glands were prepared and the ultrastructure (especially the mouthparts) of Demodex was observed firstly with environmental scanning electron microscopy (ESEM). The most suitable treatment methods and optimal environmental condition for observing the genus samples were found. The samples were washed with detergent and rinsed with distilled water, and then were taken to the specimen stage, on which there was carbon adhesive tape, using special tools. When the temperature was at 5 degrees C and chamber pressure at 5 mbar respectively, the surface of the samples could be fully imaged without covering water or dehydration. The sample surfaces were plump and clear without postmortem changes and charging artifacts. Detailed information about each part of Demodex was observed by ESEM, and clear three-dimensional images were recorded. The mouthparts of D. folliculorum were composed of a complex set of structures, which included a round oral opening, a sharp oral needle, and a special hypostome that looked like a longitudinal spindle in the central position. On the end segment of palpus, there were seven strong palpal claws located on each side of the mouthparts. D. folliculorum had special piercing mouthparts, while the mouthparts of D. brevis were a simpler structure. We could not observe the oral needle of D. brevis, and there were only five pairs of palpal claws on the end segment of palpus. The offensive organs of Demodex resulted in its pathogenic effects. After studying hundreds of Demodex, we identified both female and male species of D. folliculorum, but only females of D. brevis in our sample. PMID:16315233

Jing, Xu; Shuling, Guo; Ying, Liu

2005-12-01

394

Error rates in buccal-dental microwear quantification using scanning electron microscopy  

Microsoft Academic Search

Summary: Dental microwear, usually analyzed using scanning electron microscopy (SEM) techniques, is a good indicator of the abrasive potential of past human popula- tion diets. Scanning electron microscopy secondary elec- trons provide excellent images of dental enamel relief for characterizing striation density, average length, and orien- tation. However, methodological standardization is re- quired for interobserver comparisons since semiautomatic counting procedures

J. Galbany; L. M. Martínez; H. M. López-Amor; V. Espurz; O. Hiraldo; A. Romero; A. Pérez-Pérez

2006-01-01

395

Transmission electron microscopy investigation of auto catalyst and cobalt germanide  

NASA Astrophysics Data System (ADS)

The modern ceria-zirconia based catalysts are used in automobiles to reduce exhaust pollutants. Cobalt germanides have potential applications as electrical contacts in the future Ge-based semiconductor devices. In this thesis, transmission electron microscopy (TEM) techniques were used to study the atomic scale interactions between metallic nanostructures and crystalline substrates in the two material systems mentioned above. The model catalyst samples consisted of precious metal nano-particles (Pd, Rh) supported on the surface of (Ce,Zr)O2 thin films. The response of the microstructure of the metal-oxide interface to the reduction and oxidation treatments was investigated by cross-sectional high resolution TEM. Atomic detail of the metal-oxide interface was obtained. It was found that Pd and Rh showed different sintering and interaction behaviors on the oxide surface. The preferred orientation of Pd particles in this study was Pd(111)//CZO(111). Partial encapsulation of Pd particles by reduced (Ce,Zr)O 2 surface was observed and possible mechanisms of the encapsulation were discussed. The characteristics of the metal-oxide interaction depend on the properties of the oxide, as well as their relative orientation. The results provide experimental evidence for understanding the thermodynamics of the equilibrium morphology of a solid particle supported on a solid surface that is not considered as inert. The reaction of Co with Ge to form epitaxial Co5Ge7 was studied by in situ ultra-high vacuum (UHV) TEM using two methods. One was reactive deposition of Co on Ge, in which the Ge substrate was maintained at 350°C during deposition. The other method was solid state reaction, in which the deposition of Co on Ge was carried out at room temperature followed by annealing to higher temperatures. During reactive deposition, the deposited Co reacted with Ge to form nanosized 3D Co 5Ge7 islands. During solid state reaction, a continuous epitaxial Co5Ge7 film on the (001) Ge substrate was formed at ˜300°C. With further annealing at a higher temperature, the continuous Co5Ge 7 layer broke into 3D islands in order to relieve the strain energy in the epitaxial Co5Ge7 layer. Electron diffraction and X-ray diffraction were used to identify the cobalt germanide phase and epitaxial orientation relationships with respect to the substrate.

Sun, Haiping

396

Reflection contrast microscopy of ultrathin sections in immunocytochemical localization studies: a versatile technique bridging electron microscopy with light microscopy  

Microsoft Academic Search

Reflection contrast microscopy (RCM) of ultrathin sections was recently introduced as a sensitive technique for visualization with enhanced definition in immunogold histochemistry. Experience of using RCM as a major tool in immunocytochemical research in different fields is summarized, e.g. oncology, nephrology and embryology. The sensitive visualization of immunocytochemical labels, gold particles or peroxidase-diaminobenzidine deposits in or on ultrathin sections, by

Frans A. Prins; Ronnie Diemen-Steenvoorde; Jan Bonnet; Ingrid Cornelese-ten Velde

1993-01-01

397

Quantitative analysis of photoactivated localization microscopy (PALM) datasets using pair-correlation analysis.  

PubMed

Pointillistic based super-resolution techniques, such as photoactivated localization microscopy (PALM), involve multiple cycles of sequential activation, imaging, and precise localization of single fluorescent molecules. A super-resolution image, having nanoscopic structural information, is then constructed by compiling all the image sequences. Because the final image resolution is determined by the localization precision of detected single molecules and their density, accurate image reconstruction requires imaging of biological structures labeled with fluorescent molecules at high density. In such image datasets, stochastic variations in photon emission and intervening dark states lead to uncertainties in identification of single molecules. This, in turn, prevents the proper utilization of the wealth of information on molecular distribution and quantity. A recent strategy for overcoming this problem is pair-correlation analysis applied to PALM. Using rigorous statistical algorithms to estimate the number of detected proteins, this approach allows the spatial organization of molecules to be quantitatively described. PMID:22447653

Sengupta, Prabuddha; Lippincott-Schwartz, Jennifer

2012-03-23

398

Quantitative Characterization of Biological Liquids for Third-Harmonic Generation Microscopy  

PubMed Central

Third-harmonic generation (THG) microscopy provides images of unstained biological samples based on spatial variations in third-order nonlinear susceptibility, refractive index, and dispersion. In this study, we establish quantitative values for the third-order nonlinear susceptibilities of several solvents (water, ethanol, glycerol), physiological aqueous (ions, amino acids, polypeptides, bovine serum albumin, glucose) and lipid (triglycerides, cholesterol) solutions as a function of solute concentration in the 1.05–1.25 ?m excitation range. We use these data in conjunction with imaging experiments to show that THG imaging with ?1.2 ?m excitation lacks specificity and sensitivity to detect physiological ion concentration changes, and that nonaqueous structures such as lipid bodies provide a more robust source of signal. Finally, we illustrate the impact of index-matching liquids in THG images. These data provide a basis for interpreting biological THG images and for developing additional applications.

Debarre, Delphine; Beaurepaire, Emmanuel

2007-01-01

399

Quantitative comparison between full-spectrum and filter-based imaging in hyperspectral fluorescence microscopy.  

PubMed

We implement a filterless illumination scheme on a hyperspectral fluorescence microscope to achieve full-range spectral imaging. The microscope employs polarisation filtering, spatial filtering and spectral unmixing filtering to replace the role of traditional filters. Quantitative comparisons between full-spectrum and filter-based microscopy are provided in the context of signal dynamic range and accuracy of measured fluorophores' emission spectra. To show potential applications, a five-colour cell immunofluorescence imaging experiment is theoretically simulated. Simulation results indicate that the use of proposed full-spectrum imaging technique may result in three times improvement in signal dynamic range compared to that can be achieved in the filter-based imaging. PMID:22356127

Gao, L; Hagen, N; Tkaczyk, T S

2012-02-22

400

Quantitative comparison between full-spectrum and filter-based imaging in hyperspectral fluorescence microscopy  

PubMed Central

Summary We implement a filterless illumination scheme on a hyperspectral fluorescence microscope to achieve full-range spectral imaging. The microscope employs polarisation filtering, spatial filtering and spectral unmixing filtering to replace the role of traditional filters. Quantitative comparisons between full-spectrum and filter-based microscopy are provided in the context of signal dynamic range and accuracy of measured fluorophores’ emission spectra. To show potential applications, a five-colour cell immunofluorescence imaging experiment is theoretically simulated. Simulation results indicate that the use of proposed full-spectrum imaging technique may result in three times improvement in signal dynamic range compared to that can be achieved in the filter-based imaging.

GAO, L.; HAGEN, N.; TKACZYK, T.S.

2012-01-01

401

Quantitative microscopy and nanoscopy of sickle red blood cells performed by wide field digital interferometry  

NASA Astrophysics Data System (ADS)

We have applied wide-field digital interferometry (WFDI) to examine the morphology and dynamics of live red blood cells (RBCs) from individuals who suffer from sickle cell anemia (SCA), a genetic disorder that affects the structure and mechanical properties of RBCs. WFDI is a noncontact, label-free optical microscopy approach that can yield quantitative thickness profiles of RBCs and measurements of their membrane fluctuations at the nanometer scale reflecting their stiffness. We find that RBCs from individuals with SCA are significantly stiffer than those from a healthy control. Moreover, we show that the technique is sensitive enough to distinguish classes of RBCs in SCA, including sickle RBCs with apparently normal morphology, compared to the stiffer crescent-shaped sickle RBCs. We expect that this approach will be useful for diagnosis of SCA and for determining efficacy of therapeutic agents.

Shaked, Natan T.; Satterwhite, Lisa L.; Telen, Marilyn J.; Truskey, George A.; Wax, Adam

2011-03-01

402

Quantitative phase microscopy using defocusing by means of a spatial light modulator.  

PubMed

A new method for recovery the quantitative phase information of microscopic samples is presented. It is based on a spatial light modulator (SLM) and digital image processing as key elements to extract the sample's phase distribution. By displaying a set of lenses with different focal power, the SLM produces a set of defocused images of the input sample at the CCD plane. Such recorded images are then numerically processed to retrieve phase information. This iterative process is based on the wave propagation equation and leads on a complex amplitude image containing information of both amplitude and phase distributions of the input sample diffracted wave front. The proposed configuration is a non-interferometric architecture (conventional transmission imaging mode) where no moving elements are included. Experimental results perfectly correlate with the results obtained by conventional digital holographic microscopy (DHM). PMID:20389696

Camacho, Luis; Micó, Vicente; Zalevsky, Zeev; García, Javier

2010-03-29

403

Quantitative analysis of Scanning Tunneling Microscopy images for surface structure determination: Sulfur on Re(0001)  

SciTech Connect

Scanning Tunneling Microscopy (STM) images of adsorbed atoms and molecules on single crystal substrates provide important information on surface structure and order. In many cases images are interpreted qualitatively based on other information on the system. To obtain quantitative information, a theoretical analysis of the STM image is required. A new method of calculating STM images is presented that includes a full description of the STM tip and surface structure. This method is applied to experimental STM images of sulfur adsorbed on Re(0001). Effects of adsorption site, adsorbate geometry, tip composition and tunnel gap resistance on STM image contrast are analyzed. The chemical identity of tip apex atom and substrate subsurface structure are both shown to significantly affect STM image contrast.

Ogletree, D.F.; Dunphy, J.C.; Salmeron, M.B. [Lawrence Berkeley Lab., CA (United States); Sautet, P. [ENS, Lyon (France). Lab. de Chemie Theoretique]|[Centre National de la Recherche Scientifique (CNRS), 69 - Villeurbanne (France). Inst. de Recherches sur la Catalyse

1993-02-01

404

Lipid Nanotube Encapsulating Method in Low-Energy Scanning Transmission Electron Microscopy Analyses  

NASA Astrophysics Data System (ADS)

The lipid nanotube (LNT) encapsulating method is a rational sample fixation method that can be used to mount samples for transmission electron microscopy analyses. By employing the LNT encapsulating method in 30 kV low-voltage scanning transmission electron microscopy (LV-STEM), it is possible to record multiangle images of ferritin without using the negative staining method. We have also recorded a tilted series of high-contrast LV-STEM images and reconstructed three-dimensional images. These results show that LNTs have sufficient durability for LV electron beam, and indicate the potential of the LNT encapsulating method as a sample fixation method of LV electron microscopy.

Furusho, Hirotoshi; Mishima, Yumiko; Kameta, Naohiro; Yamane, Midori; Masuda, Mitsutoshi; Asakawa, Masumi; Yamashita, Ichiro; Mori, Hirotaro; Takaoka, Akio; Shimizu, Toshimi

2009-09-01

405

Transmission electron microscopy characterization of a Yttria-stabilized zirconia coating fabricated by electron beam–physical vapor deposition  

Microsoft Academic Search

Yttria-stabilized zirconia (YSZ) film was deposited on to a metal substrate by electron beam–physical vapor deposition (EB–PVD) at 850 °C. The film was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The YSZ film predominantly consisted of the tetragonal phase with a small amount of monoclinic phase. In addition, the film was composed of inverted triangular-based pyramidal

T. Kato; K. Matsumoto; H. Matsubara; Y. Ishiwata; H. Saka; T. Hirayama; Y. Ikuhara

2005-01-01

406

Direct electron imaging in electron microscopy with monolithic active pixel sensors.  

PubMed

A new imaging device for dynamic electron microscopy is in great demand. The detector should provide the experimenter with images having sufficient spatial resolution at high speed. Immunity to radiation damage, accumulated during exposures, is critical. Photographic film, a traditional medium, is not adequate for studies that require large volumes of data or rapid recording and charge coupled device (CCD) cameras have limited resolution, due to phosphor screen coupling. CCD chips are not suitable for direct recording due to their extreme sensitivity to radiation damage. This paper discusses characterization of monolithic active pixel sensors (MAPS) in a scanning electron microscope (SEM) as well as in a transmission electron microscope (TEM). The tested devices were two versions of the MIMOSA V (MV) chip. This 1M pixel device features pixel size of 17 x 17 microm(2) and was designed in a 0.6 microm CMOS process. The active layer for detection is a thin (less than 20 microm) epitaxial layer, limiting the broadening of the electron beam. The first version of the detector was a standard imager with electronics, passivation and interconnection layers on top of the active region; the second one was bottom-thinned, reaching the epitaxial layer from the bottom. The electron energies used range from a few keV to 30 keV for SEM and from 40 to 400 keV for TEM. Deterioration of the image resolution due to backscattering was quantified for different energies and both detector versions. PMID:17346890

Deptuch, G; Besson, A; Rehak, P; Szelezniak, M; Wall, J; Winter, M; Zhu, Y

2007-01-28

407

A charge coupled device camera with electron decelerator for intermediate voltage electron microscopy  

PubMed Central

Electron microscopists are increasingly turning to intermediate voltage electron microscopes (IVEMs) operating at 300–400 kV for a wide range of studies. They are also increasingly taking advantage of slow-scan charge coupled device (CCD) cameras, which have become widely used on electron microscopes. Under some conditions, CCDs provide an improvement in data quality over photographic film, as well as the many advantages of direct digital readout. However, CCD performance is seriously degraded on IVEMs compared to the more conventional 100 kV microscopes. In order to increase the efficiency and quality of data recording on IVEMs, we have developed a CCD camera system in which the electrons are decelerated to below 100 kV before impacting the camera, resulting in greatly improved performance in both signal quality and resolution compared to other CCDs used in electron microscopy. These improvements will allow high-quality image and diffraction data to be collected directly with the CCD, enabling improvements in data collection for applications including high-resolution electron crystallography, single particle reconstruction of protein structures, tomographic studies of cell ultrastructure, and remote microscope operation. This approach will enable us to use even larger format CCD chips that are being developed with smaller pixels.

Downing, Kenneth H.; Mooney, Paul E.

2008-01-01

408

A CCD Camera with Electron Decelerator for Intermediate Voltage Electron Microscopy  

SciTech Connect

Electron microscopists are increasingly turning to Intermediate Voltage Electron Microscopes (IVEMs) operating at 300 - 400 kV for a wide range of studies. They are also increasingly taking advantage of slow-scan charge coupled device (CCD) cameras, which have become widely used on electron microscopes. Under some conditions CCDs provide an improvement in data quality over photographic film, as well as the many advantages of direct digital readout. However, CCD performance is seriously degraded on IVEMs compared to the more conventional 100 kV microscopes. In order to increase the efficiency and quality of data recording on IVEMs, we have developed a CCD camera system in which the electrons are decelerated to below 100 kV before impacting the camera, resulting in greatly improved performance in both signal quality and resolution compared to other CCDs used in electron microscopy. These improvements will allow high-quality image and diffraction data to be collected directly with the CCD, enabling improvements in data collection for applications including high-resolution electron crystallography, single-particle reconstruction of protein structures, tomographic studies of cell ultrastructure and remote microscope operation. This approach will enable us to use even larger format CCD chips that are being developed with smaller pixels.

Downing, Kenneth H; Downing, Kenneth H.; Mooney, Paul E.

2008-03-17

409

Quantitative Analyses of RAG-RSS Interactions and Conformations Revealed by Atomic Force Microscopy  

PubMed Central

During V(D)J recombination, the site specific DNA excision is dictated by the binding of RAG1/2 proteins to the conserved recombination signal sequence (RSS) within the genome. The interaction between RAG1/2 and RSS is thought to involve a large DNA distortion that is permissive for DNA cleavage. In this study, using atomic force microscopy imaging (AFM), we analyzed individual RAG-RSS complexes, in which the bending angle of RAG-associated RSS substrates could be visualized and quantified. We provided the quantitative measurement on the conformations of specific RAG-12RSS complexes. Previous data indicating the necessity of RAG2 for recombination implies a structural role in the RAG-RSS complex. Surprisingly however, no significant difference was observed in conformational bending with AFM between RAG1-12RSS and RAG1/2-12RSS. RAG1 was found sufficient to induce DNA bending and the addition of RAG2 did not change the bending profile. In addition, a pre-nicked 12RSS bound by RAG1/2 proteins displayed a conformation similar to the one observed with the intact 12RSS, implicating that no greater DNA bending occurs after the nicking step in the signal complex. Taken together, the quantitative AFM results on the components of the recombinase emphasize a tightly held complex with a bend angle value near 60°, which may be a prerequisite step for the site-specific nicking by the V(D)J recombinase.

Pavlicek, Jeffrey W.; Lyubchenko, Yuri L.; Chang, Yung

2009-01-01

410

In vivo imaging and quantitative analysis of zebrafish embryos by digital holographic microscopy.  

PubMed

Digital holographic microscopy (DHM) has been applied extensively to in vitro studies of different living cells. In this paper, we present a novel application of an off-axis DHM system to in vivo study of the development of zebrafish embryos. Even with low magnification microscope objectives, the morphological structures and individual cell types inside developing zebrafish embryos can be clearly observed from reconstructed amplitude images. We further study the dynamic process of blood flow in zebrafish embryos. A calibration routine and post-processing procedures are developed to quantify physiological parameters at different developmental stages. We measure quantitatively the blood flow as well as the heart rate to study the effects of elevated D-glucose (abnormal condition) on circulatory and cardiovascular systems of zebrafish embryos. To enhance our ability to use DHM as a quantitative tool for potential high throughput screening application, the calibration and post-processing algorithms are incorporated into an automated processing software. Our results show that DHM is an excellent non-invasive imaging technique for visualizing the cellular dynamics of organogenesis of zebrafish embryos in vivo. PMID:23082301

Gao, Jian; Lyon, Joseph A; Szeto, Daniel P; Chen, Jun

2012-09-20

411

Quantitative Kelvin Probe Force Microscopy of a Single-Walled Carbon Nanotube Transistor  

NASA Astrophysics Data System (ADS)

Kelvin Probe Force Microscopy (KPFM) is well-suited to measuring the surface potentials of nanoscale devices, including organic thin film, graphene, and silicon nanowire field effect transistors (FETs). However, a primary limitation of KPFM is long-range capacitive coupling of the probe to parts of the sample that are distant from the immediate vicinity of the probe tip. This coupling complicates quantitative measurements and limits most KPFM work to qualitative observations of work function variations. Here, we address these problems to extract potentials along current-carrying, single-walled carbon nanotube (SWNT) FETs. As a low carrier density channel only 1 nm in diameter, SWNTs have extremely weak coupling to a KPFM probe tip, and therefore they provide a unique, limiting geometry that tests the resolving power of KPFM. By directly measuring this SWNT coupling and other, spatially-varying capacitive couplings to the probe tip, we have developed a robust and quantitative method for separating the desired signal, the local surface potential, from other electrostatic effects. The technique can be readily applied to other nanoscale devices to correctly extract work functions, potential gradients, and inhomogeneities in electrochemical potential.

Fuller, Elliot; Corso, Brad; Gul, Tolga; Collins, Philip

2013-03-01

412

In vivo imaging and quantitative analysis of zebrafish embryos by digital holographic microscopy  

PubMed Central

Digital holographic microscopy (DHM) has been applied extensively to in vitro studies of different living cells. In this paper, we present a novel application of an off-axis DHM system to in vivo study of the development of zebrafish embryos. Even with low magnification microscope objectives, the morphological structures and individual cell types inside developing zebrafish embryos can be clearly observed from reconstructed amplitude images. We further study the dynamic process of blood flow in zebrafish embryos. A calibration routine and post-processing procedures are developed to quantify physiological parameters at different developmental stages. We measure quantitatively the blood flow as well as the heart rate to study the effects of elevated D-glucose (abnormal condition) on circulatory and cardiovascular systems of zebrafish embryos. To enhance our ability to use DHM as a quantitative tool for potential high throughput screening application, the calibration and post-processing algorithms are incorporated into an automated processing software. Our results show that DHM is an excellent non-invasive imaging technique for visualizing the cellular dynamics of organogenesis of zebrafish embryos in vivo.

Gao, Jian; Lyon, Joseph A.; Szeto, Daniel P.; Chen, Jun

2012-01-01

413

Atomic-Scale Imaging and Spectroscopy for In Situ Liquid Scanning Transmission Electron Microscopy  

SciTech Connect

Observation of growth, synthesis, dynamics and electrochemical reactions in the liquid state is an important yet largely unstudied aspect of nanotechnology. The only techniques that can potentially provide the insights necessary to advance our understanding of these mechanisms is simultaneous atomic-scale imaging and quantitative chemical analysis (through spectroscopy) under environmental conditions in the transmission electron microscope (TEM). In this study we describe the experimental and technical conditions necessary to obtain electron energy loss (EEL) spectra from a nanoparticle in colloidal suspension using aberration corrected scanning transmission electron microscopy (STEM) combined with the environmental liquid stage. At a fluid path length below 400 nm, atomic resolution images can be obtained and simultaneous compositional analysis can be achieved. We show that EEL spectroscopy can be used to quantify the total fluid path length around the nanoparticle, and demonstrate characteristic core-loss signals from the suspended nanoparticles can be resolved and analyzed to provide information on the local interfacial chemistry with the surrounding environment. The combined approach using aberration corrected STEM and EEL spectra with the in situ fluid stage demonstrates a plenary platform for detailed investigations of solution based catalysis and biological research.

Jungjohann, K. L.; Evans, James E.; Aguiar, Jeff; Arslan, Ilke; Browning, Nigel D.

2012-06-04

414

Method for local temperature measurement in a nanoreactor for in situ high-resolution electron microscopy.  

PubMed

In situ high-resolution transmission electron microscopy (TEM) of solids under reactive gas conditions can be facilitated by microelectromechanical system devices called nanoreactors. These nanoreactors are windowed cells containing nanoliter volumes of gas at ambient pressures and elevated temperatures. However, due to the high spatial confinement of the reaction environment, traditional methods for measuring process parameters, such as the local temperature, are difficult to apply. To address this issue, we devise an electron energy loss spectroscopy (EELS) method that probes the local temperature of the reaction volume under inspection by the electron beam. The local gas density, as measured using quantitative EELS, is combined with the inherent relation between gas density and temperature, as described by the ideal gas law, to obtain the local temperature. Using this method we determined the temperature gradient in a nanoreactor in situ, while the average, global temperature was monitored by a traditional measurement of the electrical resistivity of the heater. The local gas temperatures had a maximum of 56°C deviation from the global heater values under the applied conditions. The local temperatures, obtained with the proposed method, are in good agreement with predictions from an analytical model. PMID:23831940

Vendelbo, S B; Kooyman, P J; Creemer, J F; Morana, B; Mele, L; Dona, P; Nelissen, B J; Helveg, S

2013-04-28

415

Electron Microscopy Studies of Carbon Nanotubes, Metal Encapsulation, Fullerides, and Dispersed Carbide  

Microsoft Academic Search

The structures and morphologies of some carbon -related nanometer-size particles, including carbon nanotubes, nanoparticles, palladium (Pa) fullerides, hafnium carbide (HfC) dispersoids, and encapsulated lanthanum carbide (LaC _2), yttrium carbide (YC _2), cobalt carbide (Co_2 C), and manganese carbides (Mn_3 C, Mn_5C_2, Mn_7C_3, and Mn _{23}C_6), have been studied with high-resolution electron microscopy (HREM), scanning transmission electron microscopy (STEM), electron energy-loss

Mingqi Liu

1994-01-01

416

Transmission electron microscopy of cometary residues from micron-sized craters in the Stardust Al foils  

Microsoft Academic Search

We report transmission electron microscopy (TEM) investigations of micro-craters that originated from hypervelocity impacts of comet 81P\\/Wild 2 dust particles on the aluminium foil of the Stardust collector. The craters were selected by scanning electron microscopy (SEM) and then prepared by focused ion beam (FIB) milling techniques in order to provide electron transparent crosssections for TEM studies. The crater residues

Hugues Leroux; R. M. Stroud; Z. R. Dai; G. A. Graham; David Troadec; J. P. Bradley; Nick Teslich; Janet Borg; A. T. Kearsley; Friedrich Hörz

2008-01-01

417

Coherent and incoherent effects on the imaging and scattering process in transmission electron microscopy and off-axis electron holography.  

PubMed

The standard treatment for the different plane wave components of incoming electrons in transmission electron microscope imaging is an incoherent superposition. However, projectile electrons in transmission electron microscopes are localized in space, and therefore have to be described as coherent wave-packets. Moreover, recent developments towards ultrafast electron microscopy and dynamic transmission electron microscopy require a description using highly localized wave-packets. Here we will extend the standard stationary modeling of the elastic scattering processes in high-resolution microscopy to a fully time-dependent approach, by using the direct solution of the time-dependent Schrödinger equation. We will draw the connection to the detection of coherent wave-packets, giving explicit implications for the reconstructed waves in off-axis electron holography. Additionally the description of incoherent aberrations is extended to incorporate the influence of the biprism accurately, leading to a modified form of the damping of spatial frequencies. PMID:20673613

Koch, Werner; Lubk, Axel; Grossmann, Frank; Lichte, Hannes; Schmidt, Ruediger

2010-07-13

418

Thickness Difference: A New Filtering Tool for Quantitative Electron Diffraction  

SciTech Connect

A new way of filtering electron diffraction patterns has been discovered. Patterns from slightly different specimen thicknesses beyond the mean free path for inelastic scattering are subtracted. Only thickness sensitive information (dominantly elastic) remains. Thermal diffuse scattering and Borrmann effects are removed in addition to the inelastic signal eliminated by conventional energy filtering. One application is quantitative convergent beam electron diffraction without an energy filter. Structure factors for {alpha}-Al{sub 2}O{sub 3} have been measured with an average uncertainty of 0.25%.

Nakashima, Philip N. H. [Department of Materials Engineering, Monash University, Clayton Vic 3800 (Australia); Monash Centre for Electron Microscopy, Monash University, Clayton Vic 3800 (Australia)

2007-09-21

419

Quantifying nanoscale order in amorphous materials: simulating fluctuation electron microscopy of amorphous silicon  

NASA Astrophysics Data System (ADS)

Fluctuation electron microscopy (FEM) is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function extracted from diffraction data appears entirely amorphous. However, it remains a formidable challenge to invert the FEM data into a quantitative model of the structure. Here, we quantify the FEM method for a-Si by forward simulating the FEM data from a family of high quality atomistic models. Using a modified WWW method, we construct computational models that contain 10-40 vol% of topologically crystalline grains, 1-3 nm in diameter, in an amorphous matrix and calculate the FEM signal, which consists of the statistical variance V (k) of the dark-field image as a function of scattering vector k. We show that V (k) is a complex function of the size and volume fraction of the ordered regions present in the amorphous matrix. However, the ratio of the variance peaks as a function of k affords the size of the ordered regions; and the magnitude of the variance affords a semi-quantitative measure of the volume fraction. We have also compared models that contain various amounts of strain in the ordered regions. This analysis shows that the amount of strain in realistic models is sufficient to mute variance peaks at high k. We conclude with a comparison between the model results and experimental data.

Bogle, Stephanie N.; Voyles, Paul M.; Khare, Sanjay V.; Abelson, John R.

2007-11-01

420

Scanning electron microscopy imaging of dislocations in bulk materials, using electron channeling contrast.  

PubMed

The imaging and characterization of dislocations is commonly carried out by thin foil transmission electron microscopy (TEM) using diffraction contrast imaging. However, the thin foil approach is limited by difficult sample preparation, thin foil artifacts, relatively small viewable areas, and constraints on carrying out in situ studies. Electron channeling imaging of electron channeling contrast imaging (ECCI) offers an alternative approach for imaging crystalline defects, including dislocations. Because ECCI is carried out with field emission gun scanning electron microscope (FEG-SEM) using bulk specimens, many of the limitations of TEM thin foil analysis are overcome. This paper outlines the development of electron channeling patterns and channeling imaging to the current state of the art. The experimental parameters and set up necessary to carry out routine channeling imaging are reviewed. A number of examples that illustrate some of the advantages of ECCI over thin foil TEM are presented along with a discussion of some of the limitations on carrying out channeling contrast analysis of defect structures. PMID:16646010

Crimp, Martin A

2006-05-01

421

Quantitative vs. qualitative approaches to the electronic structure of solids  

Microsoft Academic Search

The usefulness of qualitative and quantitative theoretical approaches in solid state chemistry is discussed by considering three different types of problems: (a) the distribution of boron and carbon atoms in MB2C2 (M=Ca, La, etc.) phases, (b) the band structure and Fermi surface of low-dimensional transition metal oxides and bronzes, and (c) the correlation between the crystal and electronic structure of

Josep M. Oliva; Miquel Llunell; Pere Alemany; Enric Canadell

2003-01-01

422

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

PubMed Central

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).

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

2009-01-01

423

High resolution electron microscopy for structure and mapping  

Microsoft Academic Search

Electron microscopes are very valuable to the human genome project. Brookhaven's Scanning Transmission Electron Microscope (STEM) is unique in many respects. It is like the National Synchrotron Light Source (NSLS) or the High Flux Beam Reactor (HFBR) at Brookhaven, but on a much smaller scale. The STEM uses electrons that are focussed through the sample, and detected. It is a

J. F. Hainfeld; J. S. Wall

1988-01-01

424

Evaluations of carbon nanotube field emitters for electron microscopy  

Microsoft Academic Search

Brightness of carbon nanotube (CNT) emitters was already reported elsewhere. However, brightness of electron emitter is affected by a virtual source size of the emitter, which strongly depends on electron optical configuration around the emitter. In this work, I–V characteristics and brightness of a CNT emitter are measured under a practical field emission electron gun (e-gun) configuration to investigate availability

Hitoshi Nakahara; Yoshikazu Kusano; Takumi Kono; Yahachi Saito

2009-01-01

425

Transmission electron microscopy analysis of a coated conductor produced by chemical deposition methods  

Microsoft Academic Search

A water-based precursor solution was used to deposit a thin La2Zr2O7 layer (70nm) on a NiW substrate. The characterization of the La2Zr2O7 (LZO) consisted of X-ray diffraction, pole figures, reflection high-energy electron diffraction, scanning electron microscopy, atomic force microscopy and transmission electron microscopy (TEM) of the cross-section. The results reveal that high-quality LZO layers can be produced using completely water-based

V. Cloet; T. Thersleff; O. Stadel; S. Hoste; B. Holzapfel; I. Van Driessche

2010-01-01

426

Analytical electron microscopy characterization of uranium-contaminated soils from the Fernald Site, FY1993 report  

SciTech Connect

A combination of optical microscopy, scanning electron microscopy with backscattered electron detection (SEM/BSE), and analytical electron microscopy (AEM) is being used to determine the nature of uranium in soils from the Fernald Environmental Management Project. The information gained from these studies is being used to develop and test remediation technologies. Investigations using SEM have shown that uranium is contained within particles that are typically 1 to 100 {mu}m in diameter. Further analysis with AEM has shown that these uranium-rich regions are made up of discrete uranium-bearing phases. The distribution of these uranium phases was found to be inhomogeneous at the microscopic level.

Buck, E.C.; Cunnane, J.C.; Brown, N.R.; Dietz, N.L.

1994-10-01

427

Diffusion of chloroaluminum phthalocyanine on MoS{sub 2} surface detected by photoemission electron microscopy and metastable electron emission microscopy  

SciTech Connect

Diffusion of a large organic semiconductor molecule, chloroaluminum phthalocyanine (ClAlPc), on a cleaved MoS{sub 2} surface was detected using photoemission electron microscopy (PEEM) and metastable electron emission microscopy (MEEM). The PEEM and MEEM images showed t