These are representative sample records from related to your search topic.
For comprehensive and current results, perform a real-time search at

Quantitative characterization of electron detectors for transmission electron microscopy  

PubMed Central

A new generation of direct electron detectors for transmission electron microscopy (TEM) promises significant improvement over previous detectors in terms of their modulation transfer function (MTF) and detective quantum efficiency (DQE). However, the performance of these new detectors needs to be carefully monitored in order to optimize imaging conditions and check for degradation over time. We have developed an easy-to-use software tool, FindDQE, to measure MTF and DQE of electron detectors using images of a microscope’s built-in beam stop. Using this software, we have determined the DQE curves of four direct electron detectors currently available: the Gatan K2 Summit, the FEI Falcon I and II, and the Direct Electron DE-12, under a variety of total dose and dose rate conditions. We have additionally measured the curves for the Gatan US4000 and TVIPS F416 scintillator-based cameras. We compare the results from our new method with published curves. PMID:24189638

Ruskin, Rachel S.; Yu, Zhiheng; Grigorieff, Nikolaus



Quantitative light and scanning electron microscopy of ferret sperm.  


Sperm were obtained via electroejaculation from Domestic ferret, (Mustela putorius furo), Siberian ferret (M. eversmanni), Black-footed ferret (M. nigripes), and a hybrid between Siberian and Domestic, called the Fitch ferret (M. sp.). Comparisons of sperm were made by four different microscopy techniques to determine whether differences exist among species. First, Nomarski differential interference microscopy could be used to distinguish domestic ferret sperm from the others on the basis of the structure of the posterior part of the acrosome. Second, both silver staining, which demonstrates argentophilic protein distribution, and scanning electron microscopy (SEM), revealed differences among the morphology of sperm for each species; variation in the unique appearance of the acrosome in ferret sperm was detected especially well by SEM. To quantify differences in morphology, five sperm head parameters were measured using image analysis; light microscopy produced significantly larger values than did SEM (all parameters and all species but Fitch), and there were significant differences owing to species for all parameters but one. Generally, our data demonstrate the value of complementary techniques to distinguish among sperm of closely related species and more specifically may help establish evolutionary relationships among the ferret species studied. In addition, they provide baseline data important for the captive breeding of the endangered Black-footed ferret. PMID:1793602

Van der Horst, G; Curry, P T; Kitchin, R M; Burgess, W; Thorne, E T; Kwiatkowski, D; Parker, M; Atherton, R W



Factors influencing quantitative liquid (scanning) transmission electron microscopy  

SciTech Connect

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

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



A technique for quantitative and qualitative viewing of aquatic bacteria using scanning electron microscopy  

E-print Network


Dreier, Thomas Michael



Thermal diffuse scattering in sub-angstrom quantitative electron microscopy--phenomenon, effects and approaches  

E-print Network

diffuse scattering approximation, thus, they are restricted to cases where the lattice distortion is smallThermal diffuse scattering in sub-angstrom quantitative electron microscopy--phenomenon, effects due to thermal diffusely scattered (TDS) electrons, which were not included in the image calculation

Wang, Zhong L.


Quantitative in situ magnetization reversal studies in Lorentz microscopy and electron holography.  


A generalized procedure for the in situ application of magnetic fields by means of the excitation of the objective lens for magnetic imaging experiments in Lorentz microscopy and electron holography is quantitatively described. A protocol for applying magnetic fields with arbitrary in-plane magnitude and orientation is presented, and a freeware script for Digital Micrograph(™) is provided to assist the operation of the microscope. Moreover, a method to accurately reconstruct hysteresis loops is detailed. We show that the out-of-plane component of the magnetic field cannot be always neglected when performing quantitative measurements of the local magnetization. Several examples are shown to demonstrate the accuracy and functionality of the methods. PMID:23831132

Rodríguez, L A; Magén, C; Snoeck, E; Gatel, C; Marín, L; Serrano-Ramón, L; Prieto, J L; Muñoz, M; Algarabel, P A; Morellon, L; De Teresa, J M; Ibarra, M R



A methodology for the extraction of quantitative information from electron microscopy images at the atomic level  

NASA Astrophysics Data System (ADS)

In this paper we describe a methodology developed at the University of Cadiz (Spain) in the past few years for the extraction of quantitative information from electron microscopy images at the atomic level. This work is based on a coordinated and synergic activity of several research groups that have been working together over the last decade in two different and complementary fields: Materials Science and Computer Science. The aim of our joint research has been to develop innovative high-performance computing techniques and simulation methods in order to address computationally challenging problems in the analysis, modelling and simulation of materials at the atomic scale, providing significant advances with respect to existing techniques. The methodology involves several fundamental areas of research including the analysis of high resolution electron microscopy images, materials modelling, image simulation and 3D reconstruction using quantitative information from experimental images. These techniques for the analysis, modelling and simulation allow optimizing the control and functionality of devices developed using materials under study, and have been tested using data obtained from experimental samples.

Galindo, P. L.; Pizarro, J.; Guerrero, E.; Guerrero-Lebrero, M. P.; Scavello, G.; Yáñez, A.; Núñez-Moraleda, B. M.; Maestre, J. M.; Sales, D. L.; Herrera, M.; Molina, S. I.



Quantitative dispersion microscopy  

PubMed Central

Refractive index dispersion is an intrinsic optical property and a useful source of contrast in biological imaging studies. In this report, we present the first dispersion phase imaging of living eukaryotic cells. We have developed quantitative dispersion microscopy based on the principle of quantitative phase microscopy. The dual-wavelength quantitative phase microscope makes phase measurements at 310 nm and 400 nm wavelengths to quantify dispersion (refractive index increment ratio) of live cells. The measured dispersion of living HeLa cells is found to be around 1.088, which agrees well with that measured directly for protein solutions using total internal reflection. This technique, together with the dry mass and morphology measurements provided by quantitative phase microscopy, could prove to be a useful tool for distinguishing different types of biomaterials and studying spatial inhomogeneities of biological samples. PMID:21113234

Fu, Dan; Choi, Wonshik; Sung, Yongjin; Yaqoob, Zahid; Dasari, Ramachandra R.; Feld, Michael



Quantitative magnetic imaging at the nanometer scale by ballistic electron magnetic microscopy  

SciTech Connect

We demonstrate quantitative ballistic electron magnetic microscopy (BEMM) imaging of simple model Fe(001) nanostructures. We use in situ nanostencil shadow mask resistless patterning combined with molecular beam epitaxy deposition to prepare under ultra-high vacuum conditions nanostructured epitaxial Fe/Au/Fe/GaAs(001) spin-valves. In this epitaxial system, the magnetization of the bottom Fe/GaAs(001) electrode is parallel to the [110] direction, defining accurately the analysis direction for the BEMM experiments. The large hot-electron magnetoresistance of the Fe/Au/Fe/GaAs(001) epitaxial spin-valve allows us to image various stable magnetic configurations on the as-grown Fe(001) microstructures with a high sensitivity, even for small misalignments of both magnetic electrodes. The angular dependence of the hot-electron magnetocurrent is used to convert magnetization maps calculated by micromagnetic simulations into simulated BEMM images. The calculated BEMM images and magnetization rotation profiles show quantitative agreement with experiments and allow us to investigate the magnetic phase diagram of these model Fe(001) microstructures. Finally, magnetic domain reversals are observed under high current density pulses. This opens the way for further BEMM investigations of current-induced magnetization dynamics.

Herve, M.; Tricot, S.; Guezo, S.; Delhaye, G.; Lepine, B.; Schieffer, P.; Turban, P. [Departement Materiaux et Nanosciences, Institut de Physique de Rennes, UMR 6251, CNRS-Universite de Rennes 1, Campus de Beaulieu, Bat 11E, 35042 Rennes cedex (France)] [Departement Materiaux et Nanosciences, Institut de Physique de Rennes, UMR 6251, CNRS-Universite de Rennes 1, Campus de Beaulieu, Bat 11E, 35042 Rennes cedex (France)



Quantitative magnetic imaging at the nanometer scale by ballistic electron magnetic microscopy  

NASA Astrophysics Data System (ADS)

We demonstrate quantitative ballistic electron magnetic microscopy (BEMM) imaging of simple model Fe(001) nanostructures. We use in situ nanostencil shadow mask resistless patterning combined with molecular beam epitaxy deposition to prepare under ultra-high vacuum conditions nanostructured epitaxial Fe/Au/Fe/GaAs(001) spin-valves. In this epitaxial system, the magnetization of the bottom Fe/GaAs(001) electrode is parallel to the [110] direction, defining accurately the analysis direction for the BEMM experiments. The large hot-electron magnetoresistance of the Fe/Au/Fe/GaAs(001) epitaxial spin-valve allows us to image various stable magnetic configurations on the as-grown Fe(001) microstructures with a high sensitivity, even for small misalignments of both magnetic electrodes. The angular dependence of the hot-electron magnetocurrent is used to convert magnetization maps calculated by micromagnetic simulations into simulated BEMM images. The calculated BEMM images and magnetization rotation profiles show quantitative agreement with experiments and allow us to investigate the magnetic phase diagram of these model Fe(001) microstructures. Finally, magnetic domain reversals are observed under high current density pulses. This opens the way for further BEMM investigations of current-induced magnetization dynamics.

Hervé, M.; Tricot, S.; Guézo, S.; Delhaye, G.; Lépine, B.; Schieffer, P.; Turban, P.



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


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



Quantitative scanning transmission electron microscopy characterisation of size-selected gold clusters.  

E-print Network

??This thesis presents a systematic study on the three-dimensional atomic structures of the size-selected gold (Au) using aberration-corrected scanning transmission electron microscopy (STEM), fitted with… (more)

He, Dongsheng



Quantitative analysis of polymer colloids by cryo-transmission electron microscopy.  


The structure of colloidal latex particles in dilute suspension at room temperature is investigated by cryogenic transmission electron microscopy (cryo-TEM). Two types of particles are analyzed: (i) core particles made of polystyrene with a thin layer of poly(N-isopropylacrylamide) (PNIPAM) and (ii) core-shell particles consisting of core particles onto which a network of cross-linked PNIPAM is affixed. Both systems are also studied by small-angle X-ray scattering (SAXS). The radial density profile of both types of particles have been derived from the cryo-TEM micrographs by image processing and compared to the results obtained by SAXS. Full agreement is found for the core particles. There is a discrepancy between the two methods in case of the core-shell particles. The discrepancy is due to the buckling of the network affixed to the surface. The buckling is clearly visible in the cryo-TEM pictures. The overall dimensions derived from cryo-TEM agree well with the hydrodynamic radius of the particles. The comparison of these data with the analysis by SAXS shows that SAXS is only sensitive to the average radial structure as expected. All data show that cryo-TEM micrographs can be evaluated to yield quantitative information about the structure of colloidal particles. PMID:19317419

Crassous, J J; Rochette, C N; Wittemann, A; Schrinner, M; Ballauff, M; Drechsler, M



Quantitative scanning electron microscopy of solitary chemoreceptor cells in cyprinids and other teleosts  

Microsoft Academic Search

Synopsis Solitary chemosensory cells (SCC) occur in the epidermis of many lower, aquatic vertebrates. By scanning electron microscopy, SCC apices were counted and density distributions estimated along various transects at the head and body of 12 species of teleost fishes, 7 cyprinids, 2 perciforms, 2 catfish and 1 characinid. In contrast to taste buds (TB), the distribution of SCCs is

Kurt Kotrschal; Konrad Lorenz



Characterization and analysis of individual fly-ash particles from coal-fired power stations by a combination of optical microscopy, electron microscopy and quantitative electron microprobe analysis  

NASA Astrophysics Data System (ADS)

Quantitative electron microprobe analysis has been used to determine the inorganic chemical composition of individual fly-ash particles previously categorized on the basis of properties recognizable by light and scanning electron microscopy. Seven categories may be recognized: (1) unfused detrital minerals (principally quartz), (2) irregular-spongy particles derived from partly-fused clay minerals, (3) vesicular colourless glass (in the form of irregular particles and cenospheres) derived from viscous melts, (4) solid glass (mostly in the form of spherical particles and sometimes pigmented) derived from fluid melts, (5) dendritic iron oxide particles (mostly spherical) containing variable amounts of glass matrix, (6) crystalline iron oxide particles (mostly spherical) containing minimal amounts of glass and (7) unburnt char particles. The use of computerized energy dispersive X-ray analysis on the electron microprobe enables an analysis for all the inorganic elements present in a particle to be carried out simultaneously in about 60s. The rapidity and comprehensive nature of the procedure makes it possible to determine the composition of a large number of individual fly-ash particles in a relatively short time and thereby characterize the types and compositions that comprise the population.

Ramsden, A. R.; Shibaoka, M.


Quantitative measurements in in situ straining experiments in transmission electron microscopy.  


Several examples of recent studies by in situ straining experiments in a transmission electron microscope performed in the Toulouse group (France) are presented. In particular, quantitative measurements of the features of the dislocation motion are described. These examples deal with individual or collective propagation of dislocations, which are submitted to various types of obstacle. Different metallic materials are investigated: magnesium, intermetallics, aluminium alloys and gamma phase of a superalloy. PMID:11454154

Pettinari, F; Couret, A; Caillard, D; Molénat, G; Clément, N; Coujou, A



Using environmental scanning electron microscopy (ESEM) as a quantitative method to analyse the attachment of Giardia duodenalis to epithelial cells.  


Giardia duodenalis is a human parasite that colonises the small intestine. In some studies, it may be necessary to estimate the parasite-host adhesion index. When working in vitro, it is very difficult to determine the relative number of parasites adhered to intestinal cells because parasites might be removed from enterocytes during specimen preparation. We have encountered such difficulties with sample analyses when using light and conventional scanning electron microscopy, including the loss of adherent cells during the processing steps. In this study, we showed that environmental scanning electron microscopy (ESEM), which allows the examination of specimens at normal atmospheric pressure or in very low vacuum without any previous treatment, can be used effectively in quantitative studies of the parasite-host relationship. PMID:21908196

Maia-Brigagão, Claudia; de Souza, Wanderley



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)



Towards quantitative scanning electron microscopy: Applications to nano-scale analysis  

NASA Astrophysics Data System (ADS)

Although the Scanning Electron Microscope (SEM) has been in existence for many decades, it cannot be yet regarded as a true quantitative instrument—certainly when applied at the nanoscale. This is due to the presence of carbonaceous deposits at the surface and a poor understanding of the emission of secondary electrons from materials. In this paper, a short review is given of some of the progress made in the efforts to improve quantification in the SEM at York. We present results which strongly suggest that the currently accepted theory, which explains why there is a correlation between the secondary electron yield and the work function of a metal, is incorrect. In addition, we show that the backscattering coefficient from materials can be strongly influenced by surface layers at low primary electron energy. Finally, we present Auger electron spectra, which have been acquired at high speed at high vacuum (10 -7 mbar) and thus represent a new way to determine the composition of nanostructures in the SEM.

El-Gomati, M. M.; Walker, C. G. H.; Zha, X.



Size-dependent second virial coefficients of quantum dots from quantitative cryogenic electron microscopy.  


Cryogenic transmission electron microscopy (cryo-TEM) is utilized to determine the second virial coefficient of osmotic pressure of PbSe quantum dots (QDs) dispersed in apolar liquid. Cryo-TEM images from vitrified samples provide snapshots of the equilibrium distribution of the particles. These snapshots yield radial distribution functions from which second virial coefficients are calculated, which agree with second virial coefficients determined with analytical centrifugation and small-angle X-ray scattering. The size dependence of the second virial coefficient points to an interparticle interaction that is proportional to the QD surface area. A plausible cause for this attraction is the interaction between the surface ions on adjacent QDs. PMID:25153168

van Rijssel, J; Peters, V F D; Meeldijk, J D; Kortschot, R J; van Dijk-Moes, R J A; Petukhov, A V; Erné, B H; Philipse, A P



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. PMID:22709926



Bidirectional quantitative force gradient microscopy  

NASA Astrophysics Data System (ADS)

Dynamic operation modes of scanning force microscopy based on probe resonance frequency detection are very successful methods to study force-related properties of surfaces with high spatial resolution. There are well-recognized approaches to measure vertical force components as well as setups sensitive to lateral force components. Here, we report on a concept of bidirectional force gradient microscopy that enables a direct, fast, and quantitative real space mapping of force component derivatives in both the perpendicular and a lateral direction. It relies solely on multiple-mode flexural cantilever oscillations related to vertical probe excitation and vertical deflection sensing. Exploring this concept we present a cantilever-based sensor setup and corresponding quantitative measurements employing magnetostatic interactions with emphasis on the calculation of mode-dependent spring constants that are the foundation of quantitative force gradient studies.

Reiche, Christopher F.; Vock, Silvia; Neu, Volker; Schultz, Ludwig; Büchner, Bernd; Mühl, Thomas



Application of Quantitative Analytical Electron Microscopy to the Mineral Content of Insect Cuticle  

NASA Astrophysics Data System (ADS)

Quantification of calcium in the cuticle of the fly larva Exeretonevra angustifrons was undertaken at the micron scale using wavelength dispersive X-ray microanalysis, analytical standards, and a full matrix correction. Calcium and phosphorus were found to be present in the exoskeleton in a ratio that indicates amorphous calcium phosphate. This was confirmed through electron diffraction of the calcium-containing tissue. Due to the pragmatic difficulties of measuring light elements, it is not uncommon in the field of entomology to neglect the use of matrix corrections when performing microanalysis of bulk insect specimens. To determine, firstly, whether such a strategy affects the outcome and secondly, which matrix correction is preferable, phi-rho (z) and ZAF matrix corrections were contrasted with each other and without matrix correction. The best estimate of the mineral phase was found to be given by using the phi-rho (z) correction. When no correction was made, the ratio of Ca to P fell outside the range for amorphous calcium phosphate, possibly leading to flawed interpretation of the mineral form when used on its own.

Rasch, Ron; Cribb, Bronwen W.; Barry, John; Palmer, Christopher M.



Mitochondrial morphology, topology, and membrane interactions in skeletal muscle: a quantitative three-dimensional electron microscopy study.  


Dynamic remodeling of mitochondrial morphology through membrane dynamics are linked to changes in mitochondrial and cellular function. Although mitochondrial membrane fusion/fission events are frequent in cell culture models, whether mitochondrial membranes dynamically interact in postmitotic muscle fibers in vivo remains unclear. Furthermore, a quantitative assessment of mitochondrial morphology in intact muscle is lacking. Here, using electron microscopy (EM), we provide evidence of interacting membranes from adjacent mitochondria in intact mouse skeletal muscle. Electron-dense mitochondrial contact sites consistent with events of outer mitochondrial membrane tethering are also described. These data suggest that mitochondrial membranes interact in vivo among mitochondria, possibly to induce morphology transitions, for kiss-and-run behavior, or other processes involving contact between mitochondrial membranes. Furthermore, a combination of freeze-fracture scanning EM and transmission EM in orthogonal planes was used to characterize and quantify mitochondrial morphology. Two subpopulations of mitochondria were studied: subsarcolemmal (SS) and intermyofibrillar (IMF), which exhibited significant differences in morphological descriptors, including form factor (means ± SD for SS: 1.41 ± 0.45 vs. IMF: 2.89 ± 1.76, P < 0.01) and aspect ratio (1.97 ± 0.83 vs. 3.63 ± 2.13, P < 0.01) and circularity (0.75 ± 0.16 vs. 0.45 ± 0.22, P < 0.01) but not size (0.28 ± 0.31 vs. 0.27 ± 0.20 ?m(2)). Frequency distributions for mitochondrial size and morphological parameters were highly skewed, suggesting the presence of mechanisms to influence mitochondrial size and shape. In addition, physical continuities between SS and IMF mitochondria indicated mixing of both subpopulations. These data provide evidence that mitochondrial membranes interact in vivo in mouse skeletal muscle and that factors may be involved in regulating skeletal muscle mitochondrial morphology. PMID:23104694

Picard, Martin; White, Kathryn; Turnbull, Douglass M



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.



Virtual Scanning Electron Microscopy  

NSDL National Science Digital Library

This site from Florida State University features an interactive Java tutorial that explores various aspects of virtual scanning electron microscopy. Users can see how specimens appear when magnified in the virtual SEM. The site also features an image gallery and extensive information about different types of microscopy.

Michael W. Davidson


Quantitative characterization of virus-like particles by asymmetrical flow field flow fractionation, electrospray differential mobility analysis, and transmission electron microscopy  

Microsoft Academic Search

Here we characterize virus-like particles (VLPs) by three very distinct, orthogonal, and quantitative techni- ques: electrospray differential mobility analysis (ES-DMA), asymmetric flow field-flow fractionation with multi-angle light scattering detection (AFFFF-MALS) and transmission electron microscopy (TEM). VLPs are biomolecular parti- cles assembled from viral proteins with applications ranging from synthetic vaccines to vectors for delivery of gene and drug therapies. VLPs

Leonard F. Pease III; Daniel I. Lipin; De-Hao Tsai; Michael R. Zachariah; Linda H. L. Lua; Michael J. Tarlov; Anton P. J. Middelberg



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



Conventional transmission electron microscopy  

PubMed Central

Researchers have used transmission electron microscopy (TEM) to make contributions to cell biology for well over 50 years, and TEM continues to be an important technology in our field. We briefly present for the neophyte the components of a TEM-based study, beginning with sample preparation through imaging of the samples. We point out the limitations of TEM and issues to be considered during experimental design. Advanced electron microscopy techniques are listed as well. Finally, we point potential new users of TEM to resources to help launch their project. PMID:24482357

Winey, Mark; Meehl, Janet B.; O'Toole, Eileen T.; Giddings, Thomas H.



Scanning electron microscopy of intestinal villous structures  

E-print Network

University, Manhattan, KS. 66506, U.S.A. Summary. Scanning Electron Microscope (SEM) was used to examineScanning electron microscopy of intestinal villous structures and their putative relation electron microscope (SEM) at 5 K.V. accelerating voltage. Quantitation of the intestinal structures

Boyer, Edmond


Quantitative analysis and cartography in scanning electron microscopy: application to the study of bacterial adhesion to respiratory epithelium.  


This paper describes the coupling between a scanning electron microscope (SEM) and an image analysis workstation. The system was designed in order to drive the SEM and to analyse any sample. It allows automatic (edge detection) or semiautomatic (pointing, marking, drawing) object detection. Two types of data can be obtained: (1) topographical information, such as the location of the object within a region of interest drawn at any magnification of the microscope, or (2) quantitative data, such as morphometric characteristics of objects. In addition, high resolution maps of the section, regions of interest, and objects can be obtained with a laser printer. This software was first applied to quantitate the adhesion of the bacteria Pseudomonas aeruginosa to human respiratory epithelial cells in culture. P. aeruginosa was shown associated with ciliated cells. The second application concerned the study of the distribution of specific carbohydrate residues at the surface of the respiratory cells. The gal residues were revealed using the lectin Ricinus communis agglutinin II, adsorbed to colloidal gold particles. A relationship between the presence of adherent bacteria and labelling was shown. PMID:8490239

Colliot, G; de Bentzmann, S; Plotkowski, M C; Lebonvallet, S; Puchelle, E; Bonnet, N



Single electron tunneling force microscopy  

Microsoft Academic Search

The development and first application of a new scanning probe microscopy technique is described. This technique, called single-electron tunneling force microscopy (SETFM), is used to image and to perform spectroscopy of individual localized electronic states in completely nonconducting oxide surfaces. The SETFM detects single-electron tunneling events between a metallized atomic force microscope probe and individual electronic states by electrostatic force

Ezra Barrus Bussmann



Registration of confocal scanning laser microscopy and quantitative backscattered electron images for the temporospatial quantification of mineralization density in 18-month old thoroughbred racehorse articular calcified cartilage.  


Combined backscattered electron scanning electron microscopy (BSE SEM) and confocal scanning laser microscopy (CSLM) have been used to put tissue mineralization data into the context of soft tissue histology and fluorescent label information. Mineralization density (Dm) and linear accretion rate (LAR) are quantifiable parameters associated with mineralizing fronts within calcified tissues. Quantitative BSE (qBSE) may be used to determine Dm, while CSLM may be used to detect label fluorescence from which LAR is calculated. Eighteen-month old Thoroughbred horses received single calcein injections 19 and 8 days prior to euthanasia, labeling sites of active mineralization with fluorescent bands. Confocal scanning laser microscopy images of articular calcified cartilage (ACC) from distal third metacarpal condyles were registered to qBSE images of the same sites using an in-house program. ImageJ and Sync Windows enabled the simultaneous collection of LAR and Dm data. The repeatability of the registration and measurement protocols was determined. Dm profiles between calcein labels were explored for an association with time. Dm was 119.7 +/- 24.5 (mean +/- standard deviation) gray levels (where 0 = backscattering from monobrominated and 255 from monoiodinated dimethacrylate standards, respectively), while modal and maximum LAR were 0.45 and 3.45 microm/day, respectively. Coefficients of variation (CV) for Dm were 0.70 and 0.77% with and without repeat registration, respectively; CVs for LAR were 1.90 and 2.26% with and without repeat registration, respectively. No relationship was identified between Dm and time in the 11-day interlabel interval. Registration of CSLM to qBSE images is sufficiently repeatable for quantitative studies of equine ACC. PMID:16268174

Doube, M; Firth, E C; Boyde, A



A quantitative estimation of the exhaust, abrasion and resuspension components of particulate traffic emissions using electron microscopy  

NASA Astrophysics Data System (ADS)

The contribution of the three traffic-related components exhaust, abrasion, and resuspension to kerbside and urban background PM10 and PM1 levels was quantified based on the analysis of individual particles by scanning electron microscopy. A total of 160 samples was collected on 38 days between February and September 2009 at a kerbside and an urban background station in the urban/industrial Ruhr area (Germany). Based on size, morphology, chemical composition and stability under electron bombardment, the 111,003 particles studied in detail were classified into the following 14 particle classes: traffic/exhaust, traffic/abrasion, traffic/resuspension, carbonaceous/organic, industry/metallurgy, industry/power plants, secondary particles, (aged) sea salt, silicates, Ca sulfates, carbonates, Fe oxides/hydroxides, biological particles, and other particles. The traffic/exhaust component consists predominantly of externally mixed soot particles and soot internally mixed with secondary particles. The traffic/abrasion component contains all particles with characteristic tracer elements (Fe, Cu, Ba, Sb, Zn) for brake and tire abrasion. The traffic/resuspension component is defined by the mixing state and comprises all internally mixed particles with a high proportion of silicates or Fe oxides/hydroxides which contain soot or abrasion particles as minor constituent. In addition, silicates and Fe oxides/hydroxides internally mixed with chlorine and sulphur containing particles were also assigned to the traffic/resuspension component. The total contribution of traffic to PM10 was found to be 27% at the urban background station and 48% at the kerbside station, the corresponding values for PM1 are 15% and 39%. These values lie within the range reported in previous literature. The relative share of the different traffic components for PM10 at the kerbside station was 27% exhaust, 15% abrasion, and 58% resuspension (38%, 8%, 54% for PM1). For the urban background, the following relative shares were obtained for PM10: 22% exhaust, 22% abrasion and 56% resuspension (40%, 27%, 33% for PM1). Compared to previous publications we have observed a significantly lower portion of exhaust particles and a significantly higher portion of resuspension particles. The high abundance of resuspension particles underlines their significance for the observed adverse health effects of traffic emissions and for mitigation measures.

Weinbruch, Stephan; Worringen, Annette; Ebert, Martin; Scheuvens, Dirk; Kandler, Konrad; Pfeffer, Ulrich; Bruckmann, Peter



High speed quantitative digital microscopy  

NASA Technical Reports Server (NTRS)

Modern digital image processing hardware makes possible quantitative analysis of microscope images at high speed. This paper describes an application to automatic screening for cervical cancer. The system uses twelve MC6809 microprocessors arranged in a pipeline multiprocessor configuration. Each processor executes one part of the algorithm on each cell image as it passes through the pipeline. Each processor communicates with its upstream and downstream neighbors via shared two-port memory. Thus no time is devoted to input-output operations as such. This configuration is expected to be at least ten times faster than previous systems.

Castleman, K. R.; Price, K. H.; Eskenazi, R.; Ovadya, M. M.; Navon, M. A.



The effect of probe inaccuracies on the quantitative model-based analysis of high angle annular dark field scanning transmission electron microscopy images.  


Quantitative structural and chemical information can be obtained from high angle annular dark field scanning transmission electron microscopy (HAADF STEM) images when using statistical parameter estimation theory. In this approach, we assume an empirical parameterized imaging model for which the total scattered intensities of the atomic columns are estimated. These intensities can be related to the material structure or composition. Since the experimental probe profile is assumed to be known in the description of the imaging model, we will explore how the uncertainties in the probe profile affect the estimation of the total scattered intensities. Using multislice image simulations, we analyze this effect for Cs corrected and non-Cs corrected microscopes as a function of inaccuracies in cylindrically symmetric aberrations, such as defocus and spherical aberration of third and fifth order, and non-cylindrically symmetric aberrations, such as 2-fold and 3-fold astigmatism and coma. PMID:24462219

Martinez, G T; De Backer, A; Rosenauer, A; Verbeeck, J; Van Aert, S



Rigorous quantitative elemental microanalysis by scanning electron microscopy/energy dispersive x-ray spectrometry (SEM/EDS) with spectrum processing by NIST DTSA-II  

NASA Astrophysics Data System (ADS)

Quantitative electron-excited x-ray microanalysis by scanning electron microscopy/silicon drift detector energy dispersive x-ray spectrometry (SEM/SDD-EDS) is capable of achieving high accuracy and high precision equivalent to that of the high spectral resolution wavelength dispersive x-ray spectrometer even when severe peak interference occurs. The throughput of the SDD-EDS enables high count spectra to be measured that are stable in calibration and resolution (peak shape) across the full deadtime range. With this high spectral stability, multiple linear least squares peak fitting is successful for separating overlapping peaks and spectral background. Careful specimen preparation is necessary to remove topography on unknowns and standards. The standards-based matrix correction procedure embedded in the NIST DTSA-II software engine returns quantitative results supported by a complete error budget, including estimates of the uncertainties from measurement statistics and from the physical basis of the matrix corrections. NIST DTSA-II is available free for Java-platforms at:

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



Electron microscopy and forensic practice  

NASA Astrophysics Data System (ADS)

Electron microanalysis in forensic practice ranks among basic applications used in investigation of traces (latents, stains, etc.) from crime scenes. Applying electron microscope allows for rapid screening and receiving initial information for a wide range of traces. SEM with EDS/WDS makes it possible to observe topography surface and morphology samples and examination of chemical components. Physical laboratory of the Institute of Criminalistics Prague use SEM especially for examination of inorganic samples, rarely for biology and other material. Recently, possibilities of electron microscopy have been extended considerably using dual systems with focused ion beam. These systems are applied mainly in study of inner micro and nanoparticles , thin layers (intersecting lines in graphical forensic examinations, analysis of layers of functional glass, etc.), study of alloys microdefects, creating 3D particles and aggregates models, etc. Automated mineralogical analyses are a great asset to analysis of mineral phases, particularly soils, similarly it holds for cathode luminescence, predominantly colour one and precise quantitative measurement of their spectral characteristics. Among latest innovations that are becoming to appear also at ordinary laboratories are TOF - SIMS systems and micro Raman spectroscopy with a resolution comparable to EDS/WDS analysis (capable of achieving similar level as through EDS/WDS analysis).

Kotrlý, Marek; Turková, Ivana



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


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



Stroboscopic scanning electron microscopy  

Microsoft Academic Search

High frequency cyclic voltages on a specimen surface have been studied pictorially, in the scanning electron microscope, by applying the principle of the sampling oscilloscope. The electron beam in the microscope column is pulsed, and the phase varied with respect to that of the waveform on the specimen. With 10 ns electron probe pulse length, a microcircuit voltage distribution, which

G S Plows; W C Nixon



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.



Four-dimensional electron microscopy.  


The discovery of the electron over a century ago and the realization of its dual character have given birth to one of the two most powerful imaging instruments: the electron microscope. The electron microscope's ability to resolve three-dimensional (3D) structures on the atomic scale is continuing to affect different fields, including materials science and biology. In this Review, we highlight recent developments and inventions made by introducing the fourth dimension of time in electron microscopy. Today, ultrafast electron microscopy (4D UEM) enables a resolution that is 10 orders of magnitude better than that of conventional microscopes, which are limited by the video-camera rate of recording. After presenting the central concept involved, that of single-electron stroboscopic imaging, we discuss prototypical applications, which include the visualization of complex structures when unfolding on different length and time scales. The developed UEM variant techniques are several, and here we illucidate convergent-beam and near-field imaging, as well as tomography and scanning-pulse microscopy. We conclude with current explorations in imaging of nanomaterials and biostructures and an outlook on possible future directions in space-time, 4D electron microscopy. PMID:20378810

Zewail, Ahmed H



Quantitative phase imaging via Fourier ptychographic microscopy.  


Fourier ptychographic microscopy (FPM) is a recently developed imaging modality that uses angularly varying illumination to extend a system's performance beyond the limit defined by its optical components. The FPM technique applies a novel phase-retrieval procedure to achieve resolution enhancement and complex image recovery. In this Letter, we compare FPM data to theoretical prediction and phase-shifting digital holography measurement to show that its acquired phase maps are quantitative and artifact-free. We additionally explore the relationship between the achievable spatial and optical thickness resolution offered by a reconstructed FPM phase image. We conclude by demonstrating enhanced visualization and the collection of otherwise unobservable sample information using FPM's quantitative phase. PMID:24322147

Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei; Zheng, Guoan



Quantitative phase imaging via Fourier ptychographic microscopy  

PubMed Central

Fourier ptychographic microscopy (FPM) is a recently developed imaging modality that uses angularly varying illumination to extend a system’s performance beyond the limit defined by its optical components. The FPM technique applies a novel phase-retrieval procedure to achieve resolution enhancement and complex image recovery. In this Letter, we compare FPM data to theoretical prediction and phase-shifting digital holography measurement to show that its acquired phase maps are quantitative and artifact-free. We additionally explore the relationship between the achievable spatial and optical thickness resolution offered by a reconstructed FPM phase image. We conclude by demonstrating enhanced visualization and the collection of otherwise unobservable sample information using FPM’s quantitative phase. PMID:24322147

Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei; Zheng, Guoan



From Quantitative Microscopy to Automated Image Understanding  

PubMed Central

Quantitative microscopy has been extensively used in biomedical research and has provided significant insights into structure and dynamics at the cell and tissue level. The entire procedure of quantitative microscopy is comprised of specimen preparation, light absorption/reflection/emission from the specimen, microscope optical processing, optical/electrical conversion by a camera or detector, and computational processing of digitized images. Although many of the latest digital signal processing techniques have been successfully applied to compress, restore, and register digital microscope images, automated approaches for recognition and understanding of complex subcellular patterns in light microscope images have been far less widely used. In this review, we describe a systematic approach for interpreting protein subcellular distributions using various sets of Subcellular Location Features (SLF) in combination with supervised classification and unsupervised clustering methods. These methods can handle complex patterns in digital microscope images and the features can be applied for other purposes such as objectively choosing a representative image from a collection and performing statistical comparison of image sets. PMID:15447010

Huang, Kai; Murphy, Robert F.



Dynamic imaging with electron microscopy  


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

Campbell, Geoffrey; McKeown, Joe; Santala, Melissa



Electron microscopy of quantum dots.  


This brief review describes the different types of semiconductor quantum dot systems, their main applications and which types of microscopy methods are used to characterize them. Emphasis is put on the need for a comprehensive investigation of their size distribution, microstructure, chemical composition, strain state and electronic properties, all of which influence the optical properties and can be measured by different types of imaging, diffraction and spectroscopy methods in an electron microscope. PMID:25406030

Walther, T



Magnetic force microscopy: quantitative issues in biomaterials.  


Magnetic force microscopy (MFM) is an atomic force microscopy (AFM) based technique in which an AFM tip with a magnetic coating is used to probe local magnetic fields with the typical AFM spatial resolution, thus allowing one to acquire images reflecting the local magnetic properties of the samples at the nanoscale. Being a well established tool for the characterization of magnetic recording media, superconductors and magnetic nanomaterials, MFM is finding constantly increasing application in the study of magnetic properties of materials and systems of biological and biomedical interest. After reviewing these latter applications, three case studies are presented in which MFM is used to characterize: (i) magnetoferritin synthesized using apoferritin as molecular reactor; (ii) magnetic nanoparticles loaded niosomes to be used as nanocarriers for drug delivery; (iii) leukemic cells labeled using folic acid-coated core-shell superparamagnetic nanoparticles in order to exploit the presence of folate receptors on the cell membrane surface. In these examples, MFM data are quantitatively analyzed evidencing the limits of the simple analytical models currently used. Provided that suitable models are used to simulate the MFM response, MFM can be used to evaluate the magnetic momentum of the core of magnetoferritin, the iron entrapment efficiency in single vesicles, or the uptake of magnetic nanoparticles into cells. PMID:25050758

Passeri, Daniele; Dong, Chunhua; Reggente, Melania; Angeloni, Livia; Barteri, Mario; Scaramuzzo, Francesca A; De Angelis, Francesca; Marinelli, Fiorenzo; Antonelli, Flavia; Rinaldi, Federica; Marianecci, Carlotta; Carafa, Maria; Sorbo, Angela; Sordi, Daniela; Arends, Isabel Wce; Rossi, Marco



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



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



Nanoscale quantitative measurement of the potential of charged nanostructures by electrostatic and Kelvin probe force microscopy: unraveling electronic processes in complex materials.  


In microelectronics and biology, many fundamental processes involve the exchange of charges between small objects, such as nanocrystals in photovoltaic blends or individual proteins in photosynthetic reactions. Because these nanoscale electronic processes strongly depend on the structure of the electroactive assemblies, a detailed understanding of these phenomena requires unraveling the relationship between the structure of the nano-object and its electronic function. Because of the fragility of the structures involved and the dynamic variance of the electric potential of each nanostructure during the charge generation and transport processes, understanding this structure-function relationship represents a great challenge. This Account discusses how our group and others have exploited scanning probe microscopy based approaches beyond imaging, particularly Kelvin probe force microscopy (KPFM), to map the potential of different nanostructures with a spatial and voltage resolution of a few nanometers and millivolts, respectively. We describe in detail how these techniques can provide researchers several types of chemical information. First, KPFM allows researchers to visualize the photogeneration and splitting of several unitary charges between well-defined nano-objects having complementary electron-acceptor and -donor properties. In addition, this method maps charge injection and transport in thin layers of polycrystalline materials. Finally, KPFM can monitor the activity of immobilized chemical components of natural photosynthetic systems. In particular, researchers can use KPFM to measure the electric potential without physical contact between the tip and the nanostructure studied. These measurements exploit long-range electrostatic interactions between the scanning probe and the sample, which scale with the square of the probe-sample distance, d. While allowing minimal perturbation, these long-range interactions limit the resolution attainable in the measurement of potentials. Although the spatial resolution of KPFM is on the nanometer scale, it is inferior to that of other related techniques such as atomic force or scanning tunneling microscopy, which are based on short-range interactions scaling as d(-7) or e(-d), respectively. To overcome this problem, we have recently devised deconvolution procedures that allow us to quantify the electric potential of a nano-object removing the artifacts due to its nanometric size. PMID:20058907

Liscio, Andrea; Palermo, Vincenzo; Samorì, Paolo



Virus quantitation by transmission electron microscopy, TCID??, and the role of timing virus harvesting: a case study of three animal viruses.  


Quantitation of viruses is practised widely in both basic and applied virology. Infectious titration in cell cultures, the most common approach to it, is quite labour-intensive and alternative protocols are therefore sought. One of the alternatives is transmission electron microscope (TEM) quantitation using latex particles at a known concentration as a reference for counting virus particles. If virus TCID?? is determined in parallel, the ratio of infectious to non-infectious virus particles may be established. This study employs such an approach to compute the number of virus particles and TCID??, and establish their correlation for three viruses: Canine adenovirus 1 (CAdV-1), Feline calicivirus (FCV) and Bovine herpesvirus 1 (BoHV-1). Each of the viruses was grown in five replicates until complete cytopathology was recorded (time 0), then frozen. They were thawed, filter-sterilised and left for additional periods of 16, 32 and 48 h at 37°C. At each time point, the infectious ability of the virus was characterised by TCID50 and the number of virions quantified by TEM, in order to evaluate the influence of timing on virus harvest. The virus particle count determined by TEM did not change for any of the viruses throughout the experiment. The relationship between virus particle counts with TCID?? at time 0 showed good linearity response; their ratio was almost constant. The virus particle-to-TCID?? ratio varied between 146 and 426 (mean±SD: 282±103) for CAdV-1, between 36 and 79 (57±18) for FCV and between 110 and 249 (167±53) for BoHV-1. The proportion of non-infectious particles did not change throughout the experiment for either CAdV-1 or BoHV-1. However, a decrease in virus infectious ability disclosed by TCID?? indicated that the fraction of non-infectious particles in FCV increased 300,000 times when time 0 and 48 h were compared. The quantitation of viruses with TEM is a simple and rapid protocol for virus quantitation but account must be taken of the type of virus and harvesting time as virus counts need not necessarily correlate with virus infectious ability. PMID:23603437

Malenovska, Hana




EPA Science Inventory

Confocal Microscopy System Performance: QA tests, Quantitation and Spectroscopy. Robert M. Zucker 1 and Jeremy M. Lerner 2, 1Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research Development, U.S. Environmen...


Quantitative phase microscopy with asynchronous digital holography  

PubMed Central

We demonstrate a new method of measuring quantitative phase in imaging of biological materials. This method, asynchronous digital holography, employs knowledge of a moving fringe created by acousto-optic modulators to execute phase-shifting interferometry using two near-simultaneous interferograms. The method can be used to obtain quantitative phase images of dynamic biological samples on millisecond time scales. We present results on a standard sample, and on live cell samples. PMID:19532543

Brown, William J.; Wax, Adam



Quantitative transmission electron microscopy analysis of multi-variant grains in present L10-FePt based heat assisted magnetic recording media  

NASA Astrophysics Data System (ADS)

We present a study on atomic ordering within individual grains in granular L10-FePt thin films using transmission electron microscopy techniques. The film, used as a medium for heat assisted magnetic recording, consists of a single layer of FePt grains separated by non-magnetic grain boundaries and is grown on an MgO underlayer. Using convergent-beam techniques, diffraction patterns of individual grains are obtained for a large number of crystallites. The study found that although the majority of grains are ordered in the perpendicular direction, more than 15% of them are multi-variant, or of in-plane c-axis orientation, or disordered fcc. It was also found that these multi-variant and in-plane grains have always grown across MgO grain boundaries separating two or more MgO grains of the underlayer. The in-plane ordered portion within a multi-variant L10-FePt grain always lacks atomic coherence with the MgO directly underneath it, whereas, the perpendicularly ordered portion is always coherent with the underlying MgO grain. Since the existence of multi-variant and in-plane ordered grains are severely detrimental to high density data storage capability, the understanding of their formation mechanism obtained here should make a significant impact on the future development of hard disk drive technology.

Ho, Hoan; Zhu, Jingxi; Kulovits, Andreas; Laughlin, David E.; Zhu, Jian-Gang



Quantitative phase microscopy through differential interference imaging  

Microsoft Academic Search

An extension of Nomarski differential interference contrast microscopy enables isotropic linear phase imaging through the combination of phase shifting, two directions of shear and Fourier-space integration using a modified spiral phase transform. We apply this method to simulated and experimentally acquired images of partially absorptive test objects. A direct comparison of the computationally determined phase to the true object phase

Sharon V. King; Ariel Libertun; Rafael Piestun; Carol J. Cogswell; Chrysanthe Preza



Reflection contrast microscopy: The bridge between light and electron microscopy.  


Reflection contrast microscopy (RCM) is a light microscopic method to image cells at high definition and enhanced sensitivity compared to conventional bright-field microscopy. RCM images have very high contrast, which makes them easily applicable for digital image analysis. Because ultrathin sections are mostly used in this method, RCM also functions by bridging light with electron microscopy: the combination of ultrastructural with histochemical studies. RCM can also replace electron microscopy for rapid and simple screening of large quantities of samples for immunocytochemical staining. Special attention is paid to small biological objects, which have to be processed for RCM. If you encounter the limits of brightfield microscopy, in resolution, sensitivity or handling of the specimen, RCM will be a feasible option. Reflection contrast microscopy methods use only slightly adjusted electron microscopy methods for specimen preparation. Therefore, many familiar techniques for ultrathin specimen preparation can be applied. It is essential that only refractive index differences exist in those areas that are of interest and that the further specimen is as optically homogenic as possible, with a refractive index as close to that of glass as possible. Therefore, plastic embedding is recommended. PMID:16719365

Prins, F A; Velde, I Cornelese-ten; de Heer, E



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.



Quantitative Phase Microscopy by Multi-wavelength Phase-Shifting Interference Microscopy  

Microsoft Academic Search

The phase-shifting interference microscopy is combined with the multi-wavelength optical phase unwrapping to obtain quantitative phase profiles of microscopic objects without 2 pi discontinuities. Due to broadband light sources, images are less affected by coherent noise.

N. Warnasooriya; M. K. Kim



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.



Electron microscopy and microanalysis Two transmission electron microscopes  

E-print Network

, employing the Department's low vacuum scanning electron microscope. TEM specimen preparation TEMElectron microscopy and microanalysis Two transmission electron microscopes (TEM) and three scanning electron micro- scopes (SEM) are operated by the De- partment. Attachments for TEM include energy


Fast electron microscopy via compressive sensing  


Various technologies described herein pertain to compressive sensing electron microscopy. A compressive sensing electron microscope includes a multi-beam generator and a detector. The multi-beam generator emits a sequence of electron patterns over time. Each of the electron patterns can include a plurality of electron beams, where the plurality of electron beams is configured to impart a spatially varying electron density on a sample. Further, the spatially varying electron density varies between each of the electron patterns in the sequence. Moreover, the detector collects signals respectively corresponding to interactions between the sample and each of the electron patterns in the sequence.

Larson, Kurt W; Anderson, Hyrum S; Wheeler, Jason W



Analytical electron microscopy of thin films  

NASA Astrophysics Data System (ADS)

An analytical transmission electron microscope (ATEM) yields an impressive amount of information from a single instrument. The chemical composition of small areas of a sample is often obtained by energy dispersive x-ray microanalysis (EDX). EDX is routinely used both in research and industry to obtain fractions of heavier elements (Z > 11). To allow quantitative EDX analysis of samples containing light elements (B, C, N, O, F, Mg and Si) we developed, fabricated and characterized a set of three calibration samples. These calibration specimens allow users to obtain experimental Cliff-Lorimer factors with 10% to 15% accuracy and are sufficiently stable during storage, as well as under electron beam irradiation. Quantitative electron energy-loss spectroscopy (EELS) was employed to characterize these samples. The good light-element sensitivity of EELS makes it a suitable method for chemical analysis of biological samples in ATEM. It is desirable to probe the detection limits of EELS and energy filtering transmission electron microscopy (EFTEM) as well as determine what physical processes underlying these limits. We find that a TEM/EELS system is capable quantifying of 2000 ppm of boron with about 10% accuracy and 1 mum resolution. EFTEM mapping using Gatan Image filter is capable of mapping 5000 ppm of boron with 66 nm pixel size. The minimum detectable fraction (MDF) was limited by detector gain-variations and beam-shot noise. Spatial (EFTEM or TEM/EELS) mapping of low boron concentrations is important for boron-neutron capture therapy (BNCT), a method of cancer treatment. The high spatial resolution of TEM imaging and chemical analysis was applied to study microscopic mechanism of growth of thin films deposited onto oblique (rotating) substrate. The structure of these films can vary between arrays of columns (stationary substrate), helices (slowly-rotated substrate) or pillars (fast-rotated substrate). These structures (columns, pillars, helices) are composed of many individual fibers growing simultaneously. The fiber-diameter is characteristic of the deposition material and its ratio of substrate and melting point temperatures (Ts/Tm). Our experiments show that it is possible to grow regular arrays of pillars or helices by depositing onto a substrate which has been pre-patterned with an array of artificial nuclei. The repeat distance of such regular arrays can be varied at least between 18 nm and one micrometer. The pillars and helices within a regular array have narrower size distributions than those within a random array. This property can be attributed to the regularity of shadowing within a regular array.

Malac, Marek


Quantitative DIC microscopy using a geometric phase shifter  

Microsoft Academic Search

In this paper we investigate the use of a geometric phase- shifting (GPS) technique which allows us to convert conventional transmission or reflection differential interference contrast (DIC) microscopy into a quantitative mode. A phase-shifting algorithm is employed to extract the specimen phase gradient from the mixture of phase and amplitude information which is common in DIC. Fourier techniques are then

Carol J. Cogswell; Nicholas I. Smith; Kieran G. Larkin; Parameswaran Hariharan



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. PMID:22316340

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



Very low voltage electron microscopy.  


We conclude that a 150 V scanning microscope with a resolution of 10 A is quite feasible and could have considerable value. It might consist of a field emission source, an electron gun to decelerate the electrons, a condenser lens to produce a parallel beam, a multipole corrector and a short focal length objective lens. Electrons reflected from the specimen surface would pass through a spectrometer whose principal features would be a large collecting power and low (1/200) energy resolution. Finally, we should add that such a microscope presents a considerable challenge and new opportunities for the electron optician in both lens and spectrometer design. We cannot refrain from pointing out that the Scherzer theorem does not necessarily hold for such a lens since the constraints of the theorem do not apply to this case. PMID:1028195

Crewe, A V



High-speed quantitative interferometric microscopy based phase imaging cytometer  

NASA Astrophysics Data System (ADS)

The paper proposed a simple large scale bio-sample phase detecting equipment called gravity driven phase detecting cytometer, which is based on quantitative interferometric microscopy to realize flowing red blood cells phase distribution detection. The method has advantages on high throughput phase detecting and statistical analysis with high detecting speed and in real-time. The statistical characteristics of red blood cells are useful for biological analysis and disease detection. We believe this method is shedding more light on quantitatively measurement of the phase distribution of bio-samples.

Xue, Liang; Sun, Nan; Yan, Keding; Liu, Fei; Wang, Shouyu



Accurate quantitative phase imaging through telecentric digital holographic microscopy  

NASA Astrophysics Data System (ADS)

The use of non-telecentric imaging systems in quantitative phase digital holographic microscopy introduces strong inaccuracies. We show that even negligible errors in the radius and center of curvature of the remaining quadratic phase factor introduce big errors in the numerical phase measurements. The errors depend on the position of the object in the field-of-view. However, when a telecentric imaging system is utilized for the recording of the holograms, the hybrid imaging method shows shift-invariant behavior, and therefore accurate quantitative phase imaging can be performed.

Doblas, Ana; Sánchez-Ortiga, Emilio; Martínez-Corral, Manuel; Saavedra, Genaro; Garcia-Sucerquia, Jorge



Simultaneous Correlative Scanning Electron and High-NA Fluorescence Microscopy  

PubMed Central

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

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



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.

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



Electron Microscopy of the Cell  

PubMed Central

The use of the electron microscope has added much to our knowledge of the cell. The fine structure of the component parts of the nucleus and the cytoplasm is described, and their functions are indicated. The nature and structural modifications of the plasma membrane are illustrated with particular reference to function. To illustrate the interrelationships of the nucleus and cytoplasm, the theory of protein secretion is discussed, the secretion of a particular protein or polypeptide being determined by a particular nucleotide sequence in the desoxyribonucleic acid of a chromosome, that is, by a gene. This information is transferred from nucleus to cytoplasm. It is in the cytoplasm that the majority of the work is performed while the nucleus directs the work of the cell. ImagesFig. 2Fig. 3Fig. 4Fig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14Fig. 15Fig. 16Fig. 17Fig. 18Fig. 19Fig. 20Fig. 21Fig. 22Fig. 23Fig. 24Fig. 25Fig. 26 PMID:5829410

Leeson, T. S.



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.


Quantitative phase imaging with scanning holographic microscopy: an experimental assesment  

PubMed Central

This paper demonstrates experimentally how quantitative phase information can be obtained in scanning holographic microscopy. Scanning holography can operate in both coherent and incoherent modes, simultaneously if desired, with different detector geometries. A spatially integrating detector provides an incoherent hologram of the object's intensity distribution (absorption and/or fluorescence, for example), while a point detector in a conjugate plane of the pupil provides a coherent hologram of the object's complex amplitude, from which a quantitative measure of its phase distribution can be extracted. The possibility of capturing simultaneously holograms of three-dimensional specimens, leading to three-dimensional reconstructions with absorption contrast, reflectance contrast, fluorescence contrast, as was previously demonstrated, and quantitative phase contrast, as shown here for the first time, opens up new avenues for multimodal imaging in biological studies. PMID:17132171

Indebetouw, Guy; Tada, Yoshitaka; Leacock, John



Organization of the Primate Retina: Electron Microscopy  

Microsoft Academic Search

The retinae of monkey and man have been studied by electron microscopy to identify cell types, their processes and synaptic contacts. In the inner plexiform layer, the morphological characteristics of the three types of cells (bipolar, ganglion and amacrine) are described and seven synaptic relationships are identified. The bipolar terminals contain ribbons at points of synaptic contact, and, at these

J. E. Dowling; B. B. Boycott



Scanning Transmission Electron Microscopy for Nanostructure  

E-print Network

152 6 Scanning Transmission Electron Microscopy for Nanostructure Characterization S. J. Pennycook for the characterization of nanostructures, providing a range of different imaging modes with the ability to provide task, it is often unnecessary for nanostructured materials, with sample preparation requiring nothing

Pennycook, Steve


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


Magnetotactic bacteria are of great interdisciplinary interest, since a vast field of applications from magnetic recording media to medical nanorobots is conceivable. A key feature for a further understanding is the detailed knowledge about the magnetosome chain within the bacteria. We report on two preparation procedures suitable for UHV experiments in reflective geometry. Further, we present the results of scanning electron microscopy, as well as the first photoemission electron microscopy experiments, both accessing the magnetosomes within intact magnetotactic bacteria and compare these to scanning electron microscopy data from the literature. From the images, we can clearly identify individual magnetosomes within their chains. PMID:25229674

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



Single beam Fourier transform digital holographic quantitative phase microscopy  

SciTech Connect

Quantitative phase contrast microscopy reveals thickness or height information of a biological or technical micro-object under investigation. The information obtained from this process provides a means to study their dynamics. Digital holographic (DH) microscopy is one of the most used, state of the art single-shot quantitative techniques for three dimensional imaging of living cells. Conventional off axis DH microscopy directly provides phase contrast images of the objects. However, this process requires two separate beams and their ratio adjustment for high contrast interference fringes. Also the use of two separate beams may make the system more vulnerable to vibrations. Single beam techniques can overcome these hurdles while remaining compact as well. Here, we describe the development of a single beam DH microscope providing whole field imaging of micro-objects. A hologram of the magnified object projected on to a diffuser co-located with a pinhole is recorded with the use of a commercially available diode laser and an arrayed sensor. A Fourier transform of the recorded hologram directly yields the complex amplitude at the image plane. The method proposed was investigated using various phase objects. It was also used to image the dynamics of human red blood cells in which sub-micrometer level thickness variation were measurable.

Anand, A., E-mail:; Chhaniwal, V. K.; Mahajan, S.; Trivedi, V. [Optics Laboratory, Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001 (India)] [Optics Laboratory, Applied Physics Department, Faculty of Technology and Engineering, M.S. University of Baroda, Vadodara 390001 (India); Faridian, A.; Pedrini, G.; Osten, W. [Institut für Technische Optik, Universität Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart (Germany)] [Institut für Technische Optik, Universität Stuttgart, Pfaffenwaldring 9, 70569 Stuttgart (Germany); Dubey, S. K. [Siemens Technology and Services Pvt. Ltd, Corporate Technology—Research and Technology Centre, Bangalore 560100 (India)] [Siemens Technology and Services Pvt. Ltd, Corporate Technology—Research and Technology Centre, Bangalore 560100 (India); Javidi, B. [Department of Electrical and Computer Engineering, U-4157, University of Connecticut, Storrs, Connecticut 06269-2157 (United States)] [Department of Electrical and Computer Engineering, U-4157, University of Connecticut, Storrs, Connecticut 06269-2157 (United States)



Single beam Fourier transform digital holographic quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

Quantitative phase contrast microscopy reveals thickness or height information of a biological or technical micro-object under investigation. The information obtained from this process provides a means to study their dynamics. Digital holographic (DH) microscopy is one of the most used, state of the art single-shot quantitative techniques for three dimensional imaging of living cells. Conventional off axis DH microscopy directly provides phase contrast images of the objects. However, this process requires two separate beams and their ratio adjustment for high contrast interference fringes. Also the use of two separate beams may make the system more vulnerable to vibrations. Single beam techniques can overcome these hurdles while remaining compact as well. Here, we describe the development of a single beam DH microscope providing whole field imaging of micro-objects. A hologram of the magnified object projected on to a diffuser co-located with a pinhole is recorded with the use of a commercially available diode laser and an arrayed sensor. A Fourier transform of the recorded hologram directly yields the complex amplitude at the image plane. The method proposed was investigated using various phase objects. It was also used to image the dynamics of human red blood cells in which sub-micrometer level thickness variation were measurable.

Anand, A.; Faridian, A.; Chhaniwal, V. K.; Mahajan, S.; Trivedi, V.; Dubey, S. K.; Pedrini, G.; Osten, W.; Javidi, B.



Quantitative phase-amplitude microscopy II: differential interference contrast imaging for biological TEM.  


Although phase contrast microscopy is widespread in optical microscopy, it has not been as widely adopted in transmission electron microscopy (TEM), which has therefore to a large extent relied on staining techniques to yield sufficient contrast. Those methods of phase contrast that are used in biological electron microscopy have been limited by factors such as the need for small phase shifts in very thin samples, the requirement for difficult experimental conditions, or the use of complex data analysis methods. We here demonstrate a simple method for quantitative TEM phase microscopy that is suitable for large phase shifts and requires only two images. We present a TEM phase image of unstained Radula sp. (liverwort spore). We show how the image may be transformed into the differential interference contrast image format familiar from optical microscopy. The phase images contain features not visible with the other imaging modalities. The resulting technique should permit phase contrast TEM to be performed almost as readily as phase contrast optical microscopy. PMID:12067364

McMahon, P J; Barone-Nugent, E D; Allman, B E; Nugent, K A



Quantitative artificial neural network for electronic noses  

Microsoft Academic Search

This paper reports a quantitative artificial neural network (ANN) to implement an electronic nose (enose). A new approach was proposed by the combination of ANN with fundamental aspects of analytical chemistry, especially with the concept of relative error (RE) in quantitative analysis. Thus, both the qualitative and quantitative requirements for ANN in implementing enose can be satisfied. Converging criterion while

Yu Lu; Liping Bian; Pengyuan Yang



Image Restoration in Cryo-electron Microscopy  

PubMed Central

Image restoration techniques are used to obtain, given experimental measurements, the best possible approximation of the original object within the limits imposed by instrumental conditions and noise level in the data. In molecular electron microscopy, we are mainly interested in linear methods that preserve the respective relationships between mass densities within the restored map. Here, we describe the methodology of image restoration in structural electron microscopy, and more specifically, we will focus on the problem of the optimum recovery of Fourier amplitudes given electron microscope data collected under various defocus settings. We discuss in detail two classes of commonly used linear methods, the first of which consists of methods based on pseudoinverse restoration, and which is further subdivided into mean-square error, chi-square error, and constrained based restorations, where the methods in the latter two subclasses explicitly incorporates non-white distribution of noise in the data. The second class of methods is based on the Wiener filtration approach. We show that the Wiener filter-based methodology can be used to obtain a solution to the problem of amplitude correction (or “sharpening”) of the electron microscopy map that makes it visually comparable to maps determined by X-ray crystallography, and thus amenable to comparable interpretation. Finally, we present a semi-heuristic Wiener filter-based solution to the problem of image restoration given sets of heterogeneous solutions. We conclude the chapter with a discussion of image restoration protocols implemented in commonly used single particle software packages. PMID:20888957

Penczek, Pawel A.



Differentiation of filoviruses by electron microscopy  

Microsoft Academic Search

Cultured monolayers of MA-104, Vero 76, SW-13, and DBS-FRhL-2 cells were infected with Marburg (MBG), Ebola-Sudan (EBO-S), Ebola-Zaire (EBO-Z), and Ebola-Reston (EBO-R) viruses (Filoviridae, Filovirus) and examined by electron microscopy to provide ultrastructural details of morphology and morphogenesis of these potential human pathogens. Replication of each filovirus was seen in all cell systems employed. Filoviral particles appeared to enter host

T. W. Geisbert; P. B. Jahrling



Eva Nogales: Introduction to Electron Microscopy  

NSDL National Science Digital Library

This lecture from the iBioSeminars project is presented by Eva Nogales Molecular Cell Biology Professor at the University of California, Berkeley, and it covers Visualizing Biological Structure Using Electron Microscopy: From Molecules to Cells. Transmission electron microscopy (TEM) offers the possibility of visualizing biological structures at resolution well beyond that of light microscopy. Whether you are interested in the ultrastructure of cells and organelles, or in the detailed molecular structure of biological macromolecules, different modalities of TEM can generally be applied to your system of interest. The lecture reviews the physical principles underlying image formation by the interaction of electrons with matter, introduces you to basic and advanced instruments and to sample preparation techniques. Using a number of biological examples from work in the Nogales lab, the lecture then describes the capabilities of the TEM methodology. Special emphasis is placed on the image processing methods used to obtain three-dimensional information from TEM data. The video runs 46:55 and can be downloaded in a number of formats: QuickTime, MP4, M4V, and PPT. The video can also be streamed through YouTube or iTunes U.

Nogales, Eva



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



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



The continuing value of electron microscopy in surgical pathology.  


For decades, transmission electron microscopy has played a valuable diagnostic role in surgical pathology. The continuing importance of electron microscopy, however, can be debated, given the major advances that have occurred in immunohistochemistry and other techniques. Electron microscopy retains excellent educational potential and broad research applicability, and it continues to be a necessity for the evaluation of a small subset of surgical pathology cases, such as renal biopsies and cilia specimens. The real controversy, then, centers on the contribution of electron microscopy in the evaluation of neoplasms. The opinion of many experts indicates that electron microscopy is still vital in the diagnostic assessment of some neoplasms, and that both electron microscopy and immunohistochemistry are more powerful when viewed as complementary rather than competitive techniques. For electron microscopy to be used to its potential, however, electron microscopists must function effectively as consultants. When optimally applied, electron microscopy remains an essential diagnostic tool. PMID:11206335

Tucker, J A



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



Toward quantitative Kelvin probe force microscopy of nanoscale potential distributions  

NASA Astrophysics Data System (ADS)

Kelvin probe force spectroscopy (KPFS) and finite-element method (FEM) simulations were employed to investigate the averaging effect of the work function signals of nanoscale potential distributions in Kelvin probe force microscopy (KPFM). A KPFS routine is presented that enables meaningful experimental results even for electronically inhomogeneous KPFM tips. By use of this routine a strong distance dependence of the averaging effect is revealed. A combination of KPFS experiments and FEM simulations is applied to quantify the averaging effect, which simplifies comparison among different experiments and to theory. No influence of surface topography on the averaging effect was observed.

Baier, Robert; Leendertz, Caspar; Lux-Steiner, Martha Ch.; Sadewasser, Sascha



Quantitative Kelvin probe force microscopy of current-carrying devices  

NASA Astrophysics Data System (ADS)

Kelvin probe force microscopy (KPFM) should be a key tool for characterizing the device physics of nanoscale electronics because it can directly image electrostatic potentials. In practice, though, distant connective electrodes interfere with accurate KPFM potential measurements and compromise its applicability. A parameterized KPFM technique described here determines these influences empirically during imaging, so that accurate potential profiles can be deduced from arbitrary device geometries without additional modeling. The technique is demonstrated on current-carrying single-walled carbon nanotubes (SWNTs), directly resolving average resistances per unit length of 70 k?/?m in semimetallic SWNTs and 200 k?/?m in semiconducting SWNTs.

Fuller, Elliot J.; Pan, Deng; Corso, Brad L.; Tolga Gul, O.; Gomez, Jose R.; Collins, Philip G.



Direct imaging of crystal structure and defects in metastable Ge{sub 2}Sb{sub 2}Te{sub 5} by quantitative aberration-corrected scanning transmission electron microscopy  

SciTech Connect

Knowledge about the atomic structure and vacancy distribution in phase change materials is of foremost importance in order to understand the underlying mechanism of fast reversible phase transformation. In this Letter, by combining state-of-the-art aberration-corrected scanning transmission electron microscopy with image simulations, we are able to map the local atomic structure and composition of a textured metastable Ge{sub 2}Sb{sub 2}Te{sub 5} thin film deposited by pulsed laser deposition with excellent spatial resolution. The atomic-resolution scanning transmission electron microscopy investigations display the heterogeneous defect structure of the Ge{sub 2}Sb{sub 2}Te{sub 5} phase. The obtained results are discussed. Highly oriented Ge{sub 2}Sb{sub 2}Te{sub 5} thin films appear to be a promising approach for further atomic-resolution investigations of the phase change behavior of this material class.

Ross, Ulrich; Lotnyk, Andriy, E-mail:; Thelander, Erik; Rauschenbach, Bernd [Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318 Leipzig (Germany)



Determination of elemental distribution in green micro-algae using synchrotron radiation nano X-ray fluorescence (SR-nXRF) and electron microscopy techniques--subcellular localization and quantitative imaging of silver and cobalt uptake by Coccomyxa actinabiotis.  


The newly discovered unicellular micro-alga Coccomyxa actinabiotis proves to be highly radio-tolerant and strongly concentrates radionuclides, as well as large amounts of toxic metals. This study helps in the understanding of the mechanisms involved in the accumulation and detoxification of silver and cobalt. Elemental distribution inside Coccomyxa actinabiotis cells was determined using synchrotron nano X-ray fluorescence spectroscopy at the ID22 nano fluorescence imaging beamline of the European Synchrotron Radiation Facility. The high resolution and high sensitivity of this technique enabled the assessment of elemental associations and exclusions in subcellular micro-algae compartments. A quantitative treatment of the scans was implemented to yield absolute concentrations of each endogenous and exogenous element with a spatial resolution of 100 nm and compared to the macroscopic content in cobalt and silver determined using inductively coupled plasma-mass spectrometry. The nano X-ray fluorescence imaging was complemented by transmission electron microscopy coupled to X-ray microanalysis (TEM-EDS), yielding differential silver distribution in the cell wall, cytosol, nucleus, chloroplast and mitochondria with unique resolution. The analysis of endogenous elements in control cells revealed that iron had a unique distribution; zinc, potassium, manganese, molybdenum, and phosphate had their maxima co-localized in the same area; and sulfur, copper and chlorine were almost homogeneously distributed among the whole cell. The subcellular distribution and quantification of cobalt and silver in micro-alga, assessed after controlled exposure to various concentrations, revealed that exogenous metals were mainly sequestered inside the cell rather than on mucilage or the cell wall, with preferential compartmentalization. Cobalt was homogeneously distributed outside of the chloroplast. Silver was localized in the cytosol at low concentration and in the whole cell excluding the nucleus at high concentration. Exposure to low concentrations of cobalt or silver did not alter the localization nor the concentration of endogenous elements within the cells. To our knowledge, this is the first report on element co-localization and segregation at the sub-cellular level in micro-algae by means of synchrotron nano X-ray fluorescence spectroscopy. PMID:24394991

Leonardo, T; Farhi, E; Boisson, A-M; Vial, J; Cloetens, P; Bohic, S; Rivasseau, C



Scanning electron microscopy of proliferating bile ductules.  


Rats were subjected to ligation of the common bile duct to provoke bile ductular proliferation and were studied at intervals from 1 day to 6 weeks. After perfusion fixation with glutaraldehyde, and ethanol dehydration, blocks of liver were frozen in liquid nitrogen, fractured, and returned to ethanol prior to critical point drying. Examination with the scanning electron microscope showed a remarkable proliferation of bile ductules and preductules in addition to canalicular dilation. The ductules were surrounded by a longitudinal array of collagen fibers. The luminal surfaces contained many microvilli and cable-like structures, some identifiable as cilia by transmission electron microscopy. The present techniques offer the possibility for a reevaluation of obstructive jaundice and cholestasis. PMID:1160351

Brooks, S E; Reynolds, P; Audretsch, J J; Haggis, G



Extracting quantitative parameters from images in multiphoton microscopy  

NASA Astrophysics Data System (ADS)

Coherent anti-Stokes Raman scattering (CARS) microscopy allows for fast, three-dimensionally resolved detection of molecules based on vibrational contrast. In CARS, the generated signal is nonlinearly dependent upon the concentration of the vibrational mode of interest. This makes it challenging to extract quantitative parameters (such as the concentration or orientation) from CARS images of biological and synthetic samples. Because of this, many investigations which employ CARS microscopy generally only report qualitative information extracted from these images. In this thesis, three methods have been developed to extract the quantitative concentration information from CARS images. In the first, the ratio of the forward-propagating and back-reflected CARS signal generated in tissue is used to monitor the percolation of DMSO into excised human cadaver skin. Through this, we find that the maximum clearing of skin with DMSO occurs at 40% v/v. We also combine CARS with second harmonic generation (SHG) to investigate the effects of DMSO on collagen. Up to a 20% v/v concentration of DMSO in the skin, the collagen becomes disrupted, resulting in a significant drop in the generated SHG. In the second method, the ratio between the CARS resonance peak and dip is correlated with the concentration to measure the concentration of water and deuterated glycine in hair. Both molecules are found to distribute throughout the hair fiber homogenously, water at a 34% v/v concentration, and d-glycine with a 0.22 M concentration. In the final method, CARS spectra over one vibrational mode are used to extract the imaginary part of the third-order nonlinear susceptibility. This quantity is linearly dependent upon the concentration of the vibrational mode of interest. This procedure is used to determine the degree of conversion of two-photon polymerized microstructures synthesized with varying writing powers. A sigmoidal relationship is observed between the applied intensity and the degree of conversion. The last chapter investigates another quantitative parameter, the orientation, of the CH2 vibrational mode in natural (cotton) and synthetic (rayon) cellulose fibers. Coupled with SHG, this method gives insight into the origins of observed optical nonlinearities in dry and hydrated cellulose fibers.

Zimmerley, Maxwell Stuart


High resolution scanning electron microscopy of plasmodesmata.  


Symplastic transport occurs between neighbouring plant cells through functionally and structurally dynamic channels called plasmodesmata (PD). Relatively little is known about the composition of PD or the mechanisms that facilitate molecular transport into neighbouring cells. While transmission electron microscopy (TEM) provides 2-dimensional information about the structural components of PD, 3-dimensional information is difficult to extract from ultrathin sections. This study has exploited high-resolution scanning electron microscopy (HRSEM) to reveal the 3-dimensional morphology of PD in the cell walls of algae, ferns and higher plants. Varied patterns of PD were observed in the walls, ranging from uniformly distributed individual PD to discrete clusters. Occasionally the thick walls of the giant alga Chara were fractured, revealing the surface morphology of PD within. External structures such as spokes, spirals and mesh were observed surrounding the PD. Enzymatic digestions of cell wall components indicate that cellulose or pectin either compose or stabilise the extracellular spokes. Occasionally, the PD were fractured open and desmotubule-like structures and other particles were observed in their central regions. Our observations add weight to the argument that Chara PD contain desmotubules and are morphologically similar to higher plant PD. PMID:21626150

Brecknock, Sarah; Dibbayawan, Teresa P; Vesk, Maret; Vesk, Peter A; Faulkner, Christine; Barton, Deborah A; Overall, Robyn L



Quantitative atomic force microscopy image analysis of unusual filaments formed by the Acanthamoeba castellanii myosin II rod domain  

Microsoft Academic Search

We describe a quantitative analysis of Acanthamoeba castellanii myosin II rod domain images collected from atomic force microscope experiments. These images reveal that the rod domain forms a novel filament structure, most likely requiring unusual head-to-tail interactions. Similar filaments are seen also in negatively stained electron microscopy images. Truncated myosins from Acanthamoeba and other model organisms have been visualized before,

Daniel J. Rigotti; Bashkim Kokona; Theresa Horne; Eric K. Acton; Carl D. Lederman; Karl A. Johnson; Robert S. Manning; Suzanne Amador Kane; Walter F. Smith; Robert Fairman




E-print Network

in the high resolution scanning electron microscope with conventional filament have been obtained The previous article presented arguments for deve- loping scanning electron. microscope techniques385 DISLOCATION IMAGES IN HIGH RESOLUTION SCANNING ELECTRON MICROSCOPY R. M. STERN Department

Paris-Sud XI, Université de


High voltage electron microscopy of lunar samples  

NASA Technical Reports Server (NTRS)

Lunar pyroxenes from Apollo 11, 12, 14, and 15 were investigated. The iron-rich and magnesium-rich pyroxene specimens were crushed to a grain size of ca. 50 microns and studied by a combination of X-ray and electron diffraction, electron microscopy, 57 Fe Mossbauer spectroscopy and X-ray crystallography techniques. Highly ordered, uniform electron-dense bands, corresponding to exsolution lamellae, with average widths of ca. 230A to 1000A dependent on the source specimen were observed. These were?qr separated by wider, less-dense interband spacings with average widths of ca. 330A to 3100A. In heating experiments, splitting of the dense bands into finer structures, leading finally to obliteration of the exsolution lamellae was recorded. The extensive exsolution is evidence for significantly slower cooling rates, or possibly annealing, at temperatures in the subsolidus range, adding evidence that annealing of rock from the surface of the moon took place at ca. 600 C. Correlation of the band structure with magnetic ordering at low temperatures and iron clustering within the bands was studied.

Fernandez-Moran, H.



Scanning electron microscopy of adult Echinostoma malayanum.  


Scanning electron microscopy observations of E. malayanum adult obtained from small intestines of infected rats was made. The number of collar spines were 41. The features observed were a pair of corner spines (3 oral and 2 aboral) total 10; a pair of lateral collar spines (10 spines each side); total 20; dorsal collar spines (5 oral and 6 aboral) total 11. Sensory papillae were found more densely situated on the circumoral disc around the oral sucker and on the ventral sucker. Other sensory organs, dome shaped, found only on the circumoral disc. The scales appear mainly on the ventral surface. The microvilli are present on the tegument where the scales occur, while the other part of dorsal side had pitted tegument. PMID:3672186

Tesana, S; Kanla, P; Maleewong, W; Kaewkes, S



Freeze-fracture for scanning electron microscopy.  


Two different freeze-fracture methods are explored for preparation of biological material for scanning electron microscopy. In the simpler method the tissues are first fixed and dehydrated. They are then frozen and fractured, and after thawing, critical-point dried. This method has already been used in a number of studies of animal tissues (heart, liver, kidney). It is applied here to the examination of plant material (leaf mesophyll cells). In the second method tissues, or cells, are first infiltrated with cryoprotectant (dimethylsulphoxide) then frozen and fractured, and not fixed until after thawing. The fixed tissues are finally dehydrated and critical-point dried. This method also has previously been used in the study of animal tissues, and is applied here to carrot protoplasts, chicken erythrocytes, and leaf mesophyll cells. PMID:599555

Haggis, G H; Phipps-Todd, B



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.



Quantitative high dynamic range beam profiling for fluorescence microscopy  

NASA Astrophysics Data System (ADS)

Modern developmental biology relies on optically sectioning fluorescence microscope techniques to produce non-destructive in vivo images of developing specimens at high resolution in three dimensions. As optimal performance of these techniques is reliant on the three-dimensional (3D) intensity profile of the illumination employed, the ability to directly record and analyze these profiles is of great use to the fluorescence microscopist or instrument builder. Though excitation beam profiles can be measured indirectly using a sample of fluorescent beads and recording the emission along the microscope detection path, we demonstrate an alternative approach where a miniature camera sensor is used directly within the illumination beam. Measurements taken using our approach are solely concerned with the illumination optics as the detection optics are not involved. We present a miniature beam profiling device and high dynamic range flux reconstruction algorithm that together are capable of accurately reproducing quantitative 3D flux maps over a large focal volume. Performance of this beam profiling system is verified within an optical test bench and demonstrated for fluorescence microscopy by profiling the low NA illumination beam of a single plane illumination microscope. The generality and success of this approach showcases a widely flexible beam amplitude diagnostic tool for use within the life sciences.

Mitchell, T. J.; Saunter, C. D.; O'Nions, W.; Girkin, J. M.; Love, G. D.



Quantitative high dynamic range beam profiling for fluorescence microscopy  

SciTech Connect

Modern developmental biology relies on optically sectioning fluorescence microscope techniques to produce non-destructive in vivo images of developing specimens at high resolution in three dimensions. As optimal performance of these techniques is reliant on the three-dimensional (3D) intensity profile of the illumination employed, the ability to directly record and analyze these profiles is of great use to the fluorescence microscopist or instrument builder. Though excitation beam profiles can be measured indirectly using a sample of fluorescent beads and recording the emission along the microscope detection path, we demonstrate an alternative approach where a miniature camera sensor is used directly within the illumination beam. Measurements taken using our approach are solely concerned with the illumination optics as the detection optics are not involved. We present a miniature beam profiling device and high dynamic range flux reconstruction algorithm that together are capable of accurately reproducing quantitative 3D flux maps over a large focal volume. Performance of this beam profiling system is verified within an optical test bench and demonstrated for fluorescence microscopy by profiling the low NA illumination beam of a single plane illumination microscope. The generality and success of this approach showcases a widely flexible beam amplitude diagnostic tool for use within the life sciences.

Mitchell, T. J., E-mail:; Saunter, C. D.; O’Nions, W.; Girkin, J. M.; Love, G. D. [Centre for Advanced Instrumentation and Biophysical Sciences Institute, Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)



Silver nanoparticle-induced degranulation observed with quantitative phase microscopy  

NASA Astrophysics Data System (ADS)

Monitoring a degranulation process in a live mast cell is a quite important issue in immunology and pharmacology. Because the size of a granule is normally much smaller than the resolution limit of an optical microscope system, there is no direct real-time live cell imaging technique for observing degranulation processes except for fluorescence imaging techniques. In this research, we propose optical quantitative phase microscopy (QPM) as a new observation tool to study degranulation processes in a live mast cell without any fluorescence labeling. We measure the cell volumes and the cross sectional profiles (x-z plane) of an RBL-2H3 cell and a HeLa cell, before and after they are exposed to calcium ionophore A23187 and silver nanoparticles (AgNPs). We verify that the volume and the cross sectional line profile of the RBL-2H3 cell were changed significantly when it was exposed to A23187. When 50 ?g/mL of AgNP is used instead of A23187, the measurements of cell volume and cross sectional profiles indicate that RBL-2H3 cells also follow degranulation processes. Degranulation processes for these cells are verified by monitoring the increase of intracellular calcium ([Ca2+]i) and histamine with fluorescent methods.

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



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.



Quantitative polarized light microscopy of unstained mammalian cochlear sections  

PubMed Central

Abstract. 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. PMID:23407909

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




E-print Network

A scanning electron microscope (SEM) is a microscope that produces images thanks to a focused beamUNSUPERVISED MORPHOLOGICAL MULTISCALE SEGMENTATION OF SCANNING ELECTRON MICROSCOPY IMAGES Gianni segmentation in the domain of scanning electron microscopy, which is tackled by mathematical morphology

Paris-Sud XI, Université de


Web Course Notes and References, Transmission Electron Microscopy  

NSDL National Science Digital Library

This site from the Electron Microscopy Outreach Program features a course devoted to transmission electron microscopy. The course is organized by chapters and covers the principles, design and operation of the electron microscope, contrast and image formation, image analysis, crystals, symmetry and diffraction, and Fourier image processing techniques.

Program, Electron M.; University Of California, San D.


Low-temperature electron microscopy: techniques and protocols.  


Low-temperature electron microscopy endeavors to provide "solidification of a biological specimen by cooling with the aim of minimal displacement of its components through the use of low temperature as a physical fixation strategy" (Steinbrecht and Zierold, Cryotechniques in biological electron microscopy. Springer-Verlag, Berlin, p 293, 1987). The intention is to maintain confidence that the tissue observed retains the morphology and dimensions of the living material while also ensuring soluble cellular components are not displaced. As applied to both scanning and transmission electron microscopy, cryo-electron microscopy is a strategy whereby the application of low-temperature techniques are used to reduce or remove processing artifacts which are commonly encountered in more conventional room temperature electron microscopy techniques which rely heavily on chemical fixation and heavy metal staining. Often, cryo-electron microscopy allows direct observation of specimens, which have not been stained or chemically fixed. PMID:25428009

Fleck, Roland A



Quantitative imaging of living cells by deep ultraviolet microscopy  

E-print Network

Developments in light microscopy over the past three centuries have opened new windows into cell structure and function, yet many questions remain unanswered by current imaging approaches. Deep ultraviolet microscopy ...

Zeskind, Benjamin J



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



Electron Microscopy: Phase Transition Singled Out  

SciTech Connect

One of the fundamental challenges within nanotechnology is to understand and control how nanoscale properties are initiated, evolve, and eventually terminate as a system moves from an individual nanostructure towards the meso- and macro-scale ensembles that are used in most applications. The ability to directly observe individual nanostructures and characterize their structure and composition has long been within the purview of transmission electron microscopy (TEM). The almost ubiquitous application of spherical aberration correction in TEM and in scanning-TEM (STEM) that has occurred over the last 10 years, now means it is possible to routinely characterize such nanostructures with both atomic resolution and sensitivity [1,2]. The development of temporal resolution in the TEM and the ability to study fast dynamics, on the other hand, has only recently come to the forefront of instrumentation development and is currently defined by two different approaches in the use of photoemission sources: the single shot ?s-ns dynamic TEM (DTEM) [3] and the stroboscopic ps-fs 4-D EM [4]. In the case of the DTEM, the goal is to observe the longer timescale irreversible structural changes that occur during nucleation and growth phenomena (here the single shot approach means there are enough electrons in a single pulsed beam to form a complete image). The 4-D EM focuses on a stroboscopic approach with the goal of studying very rapid reversible effects that occur during phase transitions (here an image is composed of thousands of pump-probe events each occurring with exactly the same time signature, with an individual pulse containing only a few electrons).

Browning, Nigel D.



Advanced electron microscopy characterization of multimetallic nanoparticles  

NASA Astrophysics Data System (ADS)

Research in noble metal nanoparticles has led to exciting progress in a versatile array of applications. For the purpose of better tailoring of nanoparticles activities and understanding the correlation between their structures and properties, control over the composition, shape, size and architecture of bimetallic and multimetallic nanomaterials plays an important role on revealing their new or enhanced functions for potentials application. Advance electron microscopy techniques were used to provide atomic scale insights into the structure-properties of different materials: PtPd, Au-Au3Cu, Cu-Pt, AgPd/Pt and AuCu/Pt nanoparticles. The objective of this work is to understand the physical and chemical properties of nanomaterials and describe synthesis, characterization, surface properties and growth mechanism of various bimetallic and multimetallic nanoparticles. The findings have provided us with novel and significant insights into the physical and chemical properties of noble metal nanoparticles. Different synthesis routes allowed us to synthesize bimetallic: Pt-Pd, Au-Au3Cu, Cu-Pt and trimetallic: AgPd/Pt, AuCu/Pt, core-shell and alloyed nanoparticles with monodispersed sizes, controlled shapes and tunable surface properties. For example, we have synthesized the polyhedral PtPd core-shell nanoparticles with octahedral, decahedral, and triangular plates. Decahedral PtPd core-shell structures are novel morphologies for this system. For the first time we fabricated that the Au core and Au3Cu alloyed shell nanoparticles passivated with CuS2 surface layers and characterized by Cs-corrected scanning transmission electron microscopy. The analysis of the high-resolution micrographs reveals that these nanoparticles have decahedral structure with shell periodicity, and that each of the particles is composed by Au core and Au3Cu ordered superlattice alloyed shell surrounded by CuS 2 surface layer. Additionally, we have described both experimental and theoretical methods of synthesis and growth mechanism of highly monodispersed Cu-Pt nanoclusters. The advance electron microscopy of microanalysis allowed us to study the distribution of Cu and Pt with atomistic resolution. The microanalysis revealed that Pt is embedded randomly in the Cu lattice. A novel grand canonical - Langevin dynamics simulation showed the formation of alloy structures in good agreement with the experimental evidence. Finally, we demonstrated the synthesis of AgPd-Pt trimetallic nanoparticles with two different morphologies: multiply twinned core-shell, and hollow particles. We also investigated the growth mechanism of the nanoparticles using grand canonical-Monte Carlo simulations. We found that the Pt regions grow at overpotentials on the AgPd nanoalloys, forming 3D islands at the early stages of the deposition process and presenting very good agreement between the simulated structures and those observed experimentally. Similarly, we also investigated AuCu/Pt core-shell trimetallic nanoparticles, presenting new way to control the nanoparticles morphologies due to the presence of third metal (Pt). Where, we observed the Pt layers are overgrowth on the as prepared AuCu core by Frank-van der Merwe (FM) and Stranski-Krastanov (SK) growth modes. In addition, these nanostructure presents high index facet surfaces with {211} and (321} families, that are highly open structure surfaces and interesting for the catalytic applications. The results of these studies will be useful for the future applications and the design of advanced functional nanomaterials.

Khanal, Subarna Raj


Dysprosium disilicide nanostructures on silicon(001) studied by scanning tunneling microscopy and transmission electron microscopy  

Microsoft Academic Search

The microstructure of self-assembled dysprosium silicide nanostructures on silicon(001) has been studied by scanning tunneling microscopy and transmission electron microscopy. The studies focused on nanostructures that involve multiple atomic layers of the silicide. Cross-sectional high resolution transmission electron microscopy images and fast Fourier transform analysis showed that both hexagonal and orthorhombic\\/tetragonal silicide phases were present. Both the magnitude and the

Gangfeng Ye; Jun Nogami; Martin A. Crimp



Quantitative metallography by electron backscattered diffraction.  


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




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

SciTech Connect

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

Kim, Suhyun; Kim, Joong Jung; Jung, Younheum; Lee, Kyungwoo; Byun, Gwangsun; Hwang, KyoungHwan; Lee, Sunyoung; Lee, Kyupil [Memory Analysis Science and Engineering Group, Samsung Electronics, San 16, Hwasung City, Gyeonggi-Do 445-701 (Korea, Republic of)] [Memory Analysis Science and Engineering Group, Samsung Electronics, San 16, Hwasung City, Gyeonggi-Do 445-701 (Korea, Republic of)



Electron microscopy. Ultrastable gold substrates for electron cryomicroscopy.  


Despite recent advances, the structures of many proteins cannot be determined by electron cryomicroscopy because the individual proteins move during irradiation. This blurs the images so that they cannot be aligned with each other to calculate a three-dimensional density. Much of this movement stems from instabilities in the carbon substrates used to support frozen samples in the microscope. Here we demonstrate a gold specimen support that nearly eliminates substrate motion during irradiation. This increases the subnanometer image contrast such that ? helices of individual proteins are resolved. With this improvement, we determine the structure of apoferritin, a smooth octahedral shell of ?-helical subunits that is particularly difficult to solve by electron microscopy. This advance in substrate design will enable the solution of currently intractable protein structures. PMID:25504723

Russo, Christopher J; Passmore, Lori A



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

Microsoft Academic Search

Scanning proton microscopy, scanning electron microscopy (SEM) and fluorescence microscopy have been used to probe the cytotoxicity effect of benzo[a]pyrene (BaP), ethidium bromide (EB) and nanoparticles (ZnO, Al2O3 and TiO2) on a T lymphoblastic leukemia Jurkat cell line. The increased calcium ion (from CaCl2) in the culture medium stimulated the accumulation of BaP and EB inside the cell, leading to

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



Quantitative phase restoration in differential interference contrast (DIC) microscopy  

Microsoft Academic Search

Phase contrast imaging is a specific technique in optical microscopy that is able to capture the minute structures of unlabeled biological sample from contrast generated in the variations of the object's refractive index. It is especially suitable for living cells and organisms that are hardly visible under conventional light microscopy as they barely alter the intensity and only introduce phase

Shan Shan Kou; Colin J. R. Sheppard



Three-dimensional reconstruction of a surface based on scanning electron microscopy images  

NASA Astrophysics Data System (ADS)

Modern methods of three-dimensional reconstruction of sample surfaces based on scanning electron microscopy images allow one to quantitatively estimate morphological surface characteristics (specifically, parameters of irregularities, volumes of convexities and concavities, etc.). The accuracy of the method is analyzed by an example of commercial and specially prepared test samples. Examples of application to various objects are given.

Mikhutkin, A. A.; Vasiliev, A. L.



Transmission Electron Microscopy of Itokawa Regolith Grains  

NASA Technical Reports Server (NTRS)

Introduction: In a remarkable engineering achievement, the JAXA space agency successfully recovered the Hayabusa space-craft in June 2010, following a non-optimal encounter and sur-face sampling mission to asteroid 25143 Itokawa. These are the first direct samples ever obtained and returned from the surface of an asteroid. The Hayabusa samples thus present a special op-portunity to directly investigate the evolution of asteroidal sur-faces, from the development of the regolith to the study of the effects of space weathering. Here we report on our preliminary TEM measurements on two Itokawa samples. Methods: We were allocated particles RA-QD02-0125 and RA-QD02-0211. Both particles were embedded in low viscosity epoxy and thin sections were prepared using ultramicrotomy. High resolution images and electron diffraction data were ob-tained using a JEOL 2500SE 200 kV field-emission scanning-transmission electron microscope. Quantitative maps and anal-yses were obtained using a Thermo thin-window energy-dispersive x-ray (EDX) spectrometer. Results: Both particles are olivine-rich (Fo70) with µm-sized inclusions of FeS and have microstructurally complex rims. Par-ticle RA-QD02-0125 is rounded and has numerous sub-µm grains attached to its surface including FeS, albite, olivine, and rare melt droplets. Solar flare tracks have not been observed, but the particle is surrounded by a continuous 50 nm thick, stuctur-ally disordered rim that is compositionally similar to the core of the grain. One of the surface adhering grains is pyrrhotite show-ing a S-depleted rim (8-10 nm thick) with nanophase Fe metal grains (<5 nm) decorating the outermost surface. The pyrrhotite displays a complex superstructure in its core that is absent in the S-depleted rim. Particle RA-QD02-0211 contains solar flare particle tracks (2x109 cm-2) and shows a structurally disordered rim 100 nm thick. The track density corresponds to a surface exposure of 103-104 years based on the track production rate of [1]. The dis-ordered rim is nanocrystalline with minor amorphous material between crystalline domains. Quantitative element maps show the outermost 10 nm of the disordered rim is Si-rich. Discussion and Conclusions: Both particles record the ef-fects of space weathering processes on Itokawa. Noguchi et al. [2] proposed that the disordered rims they observed on Itokawa particles largely result from solar wind radiation damage and we arrive at a similar conclusion for the two particles we analyzed. The microstructure of the S-depleted layer on the pyrrhotite grain in RA-QD02-0125 is similar to that observed in troilite irradiated with 1018 4 kV He+ [3, 4]. Prolonged irradiation has also been shown to disorder pyrrhotite such that the superstructure reflec-tions are lost [5].

Keller, Lindsay P.; Berger, E. L.



Quantitative imaging of magnetic nanoparticles using off-axis electron holography  

Microsoft Academic Search

Very few techniques are capable of providing quantitative information about the local magnetic induction in a material with nanometre spatial resolution. We have recently demonstrated that the transmission electron microscopy (TEM) technique of off-axis electron holography can be used to measure the magnetic induction in a naturally occurring titanomagnetite mineral sample with a spatial resolution of approximately 5 nm. Here

R. J. Harrison; R. E. Dunin-Borkowski; E. T. Simpson; T. Kasama; S. A. McEnroe; L. Brown; A. M. Hirt



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) PMID:19654103

Cortese, Katia; Diaspro, Alberto; Tacchetti, Carlo



Relationship between the v2PO4/amide III ratio assessed by Raman spectroscopy and the calcium content measured by quantitative backscattered electron microscopy in healthy human osteonal bone  

NASA Astrophysics Data System (ADS)

Raman microspectroscopy and quantitative backscattered electron imaging (qBEI) of bone are powerful tools to investigate bone material properties. Both methods provide information on the degree of bone matrix mineralization. However, a head-to-head comparison of these outcomes from identical bone areas has not been performed to date. In femoral midshaft cross sections of three women, 99 regions (20×20 ?) were selected inside osteons and interstitial bone covering a wide range of matrix mineralization. As the focus of this study was only on regions undergoing secondary mineralization, zones exhibiting a distinct gradient in mineral content close to the mineralization front were excluded. The same regions were measured by both methods. We found a linear correlation (R2=0.75) between mineral/matrix as measured by Raman spectroscopy and the wt. %Mineral/(100-wt. %Mineral) as obtained by qBEI, in good agreement with theoretical estimations. The observed deviations of single values from the linear regression line were determined to reflect biological heterogeneities. The data of this study demonstrate the good correspondence between Raman and qBEI outcomes in describing tissue mineralization. The obtained correlation is likely sensitive to changes in bone tissue composition, providing an approach to detect potential deviations from normal bone.

Roschger, Andreas; Gamsjaeger, Sonja; Hofstetter, Birgit; Masic, Admir; Blouin, Stéphane; Messmer, Phaedra; Berzlanovich, Andrea; Paschalis, Eleftherios P.; Roschger, Paul; Klaushofer, Klaus; Fratzl, Peter



Atomic Force Microscopy of Photosystem II and Its Unit Cell Clustering Quantitatively Delineate the Mesoscale  

E-print Network

Atomic Force Microscopy of Photosystem II and Its Unit Cell Clustering Quantitatively Delineate quenching (NPQ), which depend on the re-organization of photosystem (PS) II supercomplexes in thylakoid, Grob P, Nogales E, et al. (2014) Atomic Force Microscopy of Photosystem II and Its Unit Cell Clustering

Geissler, Phillip


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.




EPA Science Inventory

The confocal laser-scanning microscopy (CLSM) has enormous potential in many biological fields. The goal of a CLSM is to acquire and quantify fluorescence and in some instruments acquire spectral characterization of the emitted signal. The accuracy of these measurements demands t...


Serial Block-Face Scanning Electron Microscopy to Reconstruct  

E-print Network

of a scanning electron microscope. Backscattering contrast is used to visualize the heavy-metal stainingSerial Block-Face Scanning Electron Microscopy to Reconstruct Three-Dimensional Tissue at electron microscopic, and tissue at light-microscopic resolution. A gap exists, however, when 3D tissue

Born, Richard


Pars plana incisions of four patients: histopathology and electron microscopy  

Microsoft Academic Search

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

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



Label-free quantitative cell division monitoring of endothelial cells by digital holographic microscopy.  


Digital holographic microscopy (DHM) enables quantitative multifocus phase contrast imaging for nondestructive technical inspection and live cell analysis. Time-lapse investigations on human brain microvascular endothelial cells demonstrate the use of DHM for label-free dynamic quantitative monitoring of cell division of mother cells into daughter cells. Cytokinetic DHM analysis provides future applications in toxicology and cancer research. PMID:20615011

Kemper, Björn; Bauwens, Andreas; Vollmer, Angelika; Ketelhut, Steffi; Langehanenberg, Patrik; Müthing, Johannes; Karch, Helge; von Bally, Gert



Writing silica structures in liquid with scanning transmission electron microscopy.  


Silica nanoparticles are imaged in solution with scanning transmission electron microscopy (STEM) using a liquid cell with silicon nitride (SiN) membrane windows. The STEM images reveal that silica structures are deposited in well-defined patches on the upper SiN membranes upon electron beam irradiation. The thickness of the deposits is linear with the applied electron dose. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate that the deposited patches are a result of the merging of the original 20 nm-diameter nanoparticles, and that the related surface roughness depends on the electron dose rate used. Using this approach, sub-micrometer scale structures are written on the SiN in liquid by controlling the electron exposure as function of the lateral position. PMID:25207936

van de Put, Marcel W P; Carcouët, Camille C M C; Bomans, Paul H H; Friedrich, Heiner; de Jonge, Niels; Sommerdijk, Nico A J M



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


Ion-induced electron emission microscopy  


An ion beam analysis system that creates multidimensional maps of the effects of high energy ions from an unfocussed source upon a sample by correlating the exact entry point of an ion into a sample by projection imaging of the secondary electrons emitted at that point with a signal from a detector that measures the interaction of that ion within the sample. The emitted secondary electrons are collected in a strong electric field perpendicular to the sample surface and (optionally) projected and refocused by the electron lenses found in a photon emission electron microscope, amplified by microchannel plates and then their exact position is sensed by a very sensitive X Y position detector. Position signals from this secondary electron detector are then correlated in time with nuclear, atomic or electrical effects, including the malfunction of digital circuits, detected within the sample that were caused by the individual ion that created these secondary electrons in the fit place.

Doyle, Barney L. (Albuquerque, NM); Vizkelethy, Gyorgy (Albuquerque, NM); Weller, Robert A. (Brentwood, TN)



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. PMID:24156044

Chowdhury, Shwetadwip; Izatt, Joseph



Digital holographic microscopy for quantitative cell dynamic evaluation during laser microsurgery.  


Digital holographic microscopy allows determination of dynamic changes in the optical thickness profile of a transparent object with sub-wavelength 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. PMID:19582118

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



Quantitative DIC microscopy using an off-axis self-interference approach.  


Traditional Normarski differential interference contrast (DIC) microscopy is a very powerful method for imaging nonstained biological samples. However, one of its major limitations is the nonquantitative nature of the imaging. To overcome this problem, we developed a quantitative DIC microscopy method based on off-axis sample self-interference. The digital holography algorithm is applied to obtain quantitative phase gradients in orthogonal directions, which leads to a quantitative phase image through a spiral integration of the phase gradients. This method is practically simple to implement on any standard microscope without stringent requirements on polarization optics. Optical sectioning can be obtained through enlarged illumination NA. PMID:20634833

Fu, Dan; Oh, Seungeun; Choi, Wonshik; Yamauchi, Toyohiko; Dorn, August; Yaqoob, Zahid; Dasari, Ramachandra R; Feld, Michael S



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. PMID:19582118

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



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:; 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)



Combined confocal Raman and quantitative phase microscopy system for biomedical diagnosis  

PubMed Central

We have developed a novel multimodal microscopy system that incorporates confocal Raman, confocal reflectance, and quantitative phase microscopy (QPM) into a single imaging entity. Confocal Raman microscopy provides detailed chemical information from the sample, while confocal reflectance and quantitative phase microscopy show detailed morphology. Combining these intrinsic contrast imaging modalities makes it possible to obtain quantitative morphological and chemical information without exogenous staining. For validation and characterization, we have used this multi-modal system to investigate healthy and diseased blood samples. We first show that the thickness of a healthy red blood cell (RBC) shows good correlation with its hemoglobin distribution. Further, in malaria infected RBCs, we successfully image the distribution of hemozoin (malaria pigment) inside the cell. Our observations lead us to propose morphological screening by QPM and subsequent chemical imaging by Raman for investigating blood disorders. This new approach allows monitoring cell development and cell-drug interactions with minimal perturbation of the biological system of interest. PMID:21991542

Kang, Jeon Woong; Lue, Niyom; Kong, Chae-Ryon; Barman, Ishan; Dingari, Narahara C.; Goldfless, Stephen J.; Niles, Jacquin C.; Dasari, Ramachandra R.; Feld, Michael S.



Image Resolution in Scanning Transmission Electron Microscopy  

SciTech Connect

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

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



Quantitative thermal microscopy using thermoelectric probe in passive mode.  


A scanning thermal microscope working in passive mode using a micronic thermocouple probe is presented as a quantitative technique. We show that actual surface temperature distributions of microsystems are measurable under conditions for which most of usual techniques cannot operate. The quantitative aspect relies on the necessity of an appropriate calibration procedure which takes into account of the probe-to-sample thermal interaction prior to any measurement. Besides this consideration that should be treated for any thermal contact probing system, the main advantages of our thermal microscope deal with the temperature available range, the insensitivity to the surface optical parameters, the possibility to image DC, and AC temperature components up to 1 kHz typically and a resolution limit related to near-field behavior. PMID:24182115

Bontempi, A; Thiery, L; Teyssieux, D; Briand, D; Vairac, P



Electron holography and environmental transmission electron microscopy of magnetism at the nanoscale  

E-print Network

Electron holography and environmental transmission electron microscopy of magnetism holography. Interpretation of the recorded phase shift allows magnetic fields in materials and in working on the specimen surface are minimized. We are currently combining electron holography with environmental TEM

Dunin-Borkowski, Rafal E.


Dual interference channel quantitative phase microscopy of live cell dynamics  

PubMed Central

We introduce and experimentally demonstrate a new fast and accurate method for quantitative imaging of the dynamics of live biological cells. Using a dual-channel interferometric setup, two phase-shifted interferograms of nearly-transparent biological samples are acquired in a single digital camera exposure, and digitally processed into the phase profile of the sample. Since two interferograms of the same sample are acquired simultaneously, most of the common phase noise is eliminated, enabling the visualization of millisecond-scale dynamic biological phenomena with sub-nanometer optical path length temporal stability. PMID:19282926

Shaked, Natan T.; Rinehart, Matthew T.; Wax, Adam



Study on development of Agaricus bisporus by fluorescent microscopy and scanning electron microscopy.  

PubMed Central

Two strains of Agaricus bisporus have been investigated by fluorescent microscopy and scanning electron microscopy. Somatic nuclei, stained with auramin O and examined by fluorescent microscopy, appear to be randomly distributed, divide asynchronously, and assume a nonclassical or "two-track" configuration during mitotic metaphase. A similar configuration has been observed for nuclei during meiosis, but early meiosis in A. bisporus appears to be classical, usually with nine pairs of chromosomes evident during prophase I. Scanning electron microscopy has been used to document developmental stages in the formation and germination of basidiospores. Two-spored basidia were predominant, but occasionally one- or three-spored forms were observed. Four-spored basidia were absent, and uninucleated basidiospores were exceedingly rare to absent. Images PMID:944181

Saksena, K N; Marino, R; Haller, M N; Lemke, P A



Scanning transmission electron microscopy study of III-V nitrides  

NASA Astrophysics Data System (ADS)

A study of the electronic properties of the III-V nitrides and the characterization of nitride-based heterostructures, interfaces and quantum wells using scanning transmission electron microscopy (STEM) are presented. Examination of the epitaxially grown GaN/Al0.25Ga0.75N heterostructure shows that, in contrast to expectations, the interface between GaN buffer and Al0.25Ga0.75N barrier is not atomically sharp, but diffuse. High spatial resolution electron energy loss spectroscopy measurements and annular dark field imaging indicate that these interfaces can be up to 20 A wide. The effects of the presence of the diffuse interface between the GaN and AlxGa1- xN layers on formation of the quasi-two-dimensional electron gas at the heterointerface are studied. Electronic energy levels and the distribution of these highly localized electrons at the interface are calculated for different interface widths and for various physical parameters of the structure. The long-range and atomic level uniformities of the GaN quantum wells grown in an AlN matrix are characterized using electron energy loss spectroscopy and annular dark field imaging. The effects of the incident electron beam broadening inside the specimen on STEM measurements are discussed and mechanisms to minimize them are suggested. For quantitative correlation, the measured intensity of the nitrogen K-edge is compared with the propagating beam intensity obtained from multislice calculations. Possible effects of strain in the structure on its electronic states and energy-loss spectra are predicted. The electron-beam-induced damage of the wurtzite InN in STEM is studied and knock-on type damage with ejection of nitrogen atoms from a sample is observed. From comparison of the measured integrated intensity of the nitrogen K-edge and indium M4,5-edge with a calculated mass-loss model the vacancy-enhanced displacement energy for nitrogen atoms in InN is obtained. Investigations of the electronic structure of the wurtzite InN are carried out and excellent agreement between measured spectra of the nitrogen K-edge and the indium M4,5 -edge and corresponding nitrogen 2p and the indium 5p partial density of states (DOS) of the conduction band is obtained. The calculations of DOS are performed using density functional theory (DFT). DFT calculations of nitrogen 2p partial DOS of the conduction band in strained and relaxed wurtzite InN combined with multiple scattering x-ray absorption near edge structure calculations of the corresponding nitrogen K-edge spectra suggest that a strong modification of the electronic structure should be expected in epitaxially grown multilayer structures when a significant mismatch in lattice constants between layers is present.

Mkhoyan, Karen Andre


Quantitative flaw characterization with scanning laser acoustic microscopy  

NASA Technical Reports Server (NTRS)

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.

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



Use of Atomic Force Microscopy and Transmission Electron Microscopy for Correlative Studies of Bacterial Capsules  

Microsoft Academic Search

Bacteria can possess an outermost assembly of polysaccharide molecules, a capsule, which is attached to their cell wall. We have used two complementary, high-resolution microscopy techniques, atomic force micros- copy (AFM) and transmission electron microscopy (TEM), to study bacterial capsules of four different gram-negative bacterial strains: Escherichia coli K30, Pseudomonas aeruginosa FRD1, Shewanella oneidensis MR-4, and Geobacter sulfurreducens PCA. TEM

Oleg Stukalov; Anton Korenevsky; Terry J. Beveridge; John R. Dutcher



Recent advances in electron imaging, image interpretation and applications: environmental scanning electron microscopy  

Microsoft Academic Search

One of the latest developments in electron microscopy is the environmental scanning electron microscope (ESEM), which enables soft, moist and\\/or electrically insulating materials to be viewed without pre-treatment, unlike conventional scanning electron microscopy, in which specimens must be solid, dry and usually electrically conductive. Such an advance has significant implications for studies of the 'native' surfaces of specimens including rocks

Debbie J. Stokes



Contributed Review: Review of integrated correlative light and electron microscopy  

NASA Astrophysics Data System (ADS)

New developments in the field of microscopy enable to acquire increasing amounts of information from large sample areas and at an increased resolution. Depending on the nature of the technique, the information may reveal morphological, structural, chemical, and still other sample characteristics. In research fields, such as cell biology and materials science, there is an increasing demand to correlate these individual levels of information and in this way to obtain a better understanding of sample preparation and specific sample properties. To address this need, integrated systems were developed that combine nanometer resolution electron microscopes with optical microscopes, which produce chemically or label specific information through spectroscopy. The complementary information from electron microscopy and light microscopy presents an opportunity to investigate a broad range of sample properties in a correlated fashion. An important part of correlating the differences in information lies in bridging the different resolution and image contrast features. The trend to analyse samples using multiple correlated microscopes has resulted in a new research field. Current research is focused, for instance, on (a) the investigation of samples with nanometer scale distribution of inorganic and organic materials, (b) live cell analysis combined with electron microscopy, and (c) in situ spectroscopic and electron microscopy analysis of catalytic materials, but more areas will benefit from integrated correlative microscopy.

Timmermans, F. J.; Otto, C.



Characterization of chemical composition and electronic structure of Pt\\/YSZ interfaces by analytical transmission electron microscopy  

Microsoft Academic Search

Platinum\\/yttria stabilized zirconia (Pt\\/YSZ) interfaces with two different orientation relationships were characterized using advanced analytical transmission electron microscopy methods. Quantitative X-ray energy dispersive spectroscopy (XEDS) was performed by the recently developed ?-factor method. Neither interdiffusion nor segregation was detected across the Pt\\/YSZ interfaces of both orientation conditions within the resolution limit of the technique. The interface specific components of the

V. Srot; M. Watanabe; C. Scheu; P. A. van Aken; U. Salzberger; B. Luerßen; J. Janek; M. Rühle



Single-cell lysis for visual analysis by electron microscopy.  


The stochastic nature of biological systems makes the study of individual cells a necessity in systems biology. Yet, handling and disruption of single cells and the analysis of the relatively low concentrations of their protein components still challenges available techniques. Transmission electron microscopy (TEM) allows for the analysis of proteins at the single-molecule level. Here, we present a system for single-cell lysis under light microscopy observation, followed by rapid uptake of the cell lysate. Eukaryotic cells were grown on conductively coated glass slides and observed by light microscopy. A custom-designed microcapillary electrode was used to target and lyse individual cells with electrical pulses. Nanoliter volumes were subsequently aspirated into the microcapillary and dispensed onto an electron microscopy grid for TEM inspection. We show, that the cell lysis and preparation method conserves protein structures well and is suitable for visual analysis by TEM. PMID:23816812

Kemmerling, Simon; Arnold, Stefan A; Bircher, Benjamin A; Sauter, Nora; Escobedo, Carlos; Dernick, Gregor; Hierlemann, Andreas; Stahlberg, Henning; Braun, Thomas



Scanning electron microscopy of soybean protein bodies  

Microsoft Academic Search

Protein bodies prepared from defatted soybean flour contained numerous spherical particles 1–3 µ in diameter, plus amorphous\\u000a material, when examined in a scanning electron microscope. Full-fat and defatted soybean flours contained particles 1–10 µ\\u000a in diameter. The larger protein bodies apparently disrupted during isolation. The scanning technique is a simple and rapid\\u000a method for observing the effects of various treatments

W. J. Wolf



CI Slide: calibration slide for quantitative microscopy imaging in absorbance  

NASA Astrophysics Data System (ADS)

New imaging technologies are changing the field of digital pathology. This field faces numerous challenges and there is a pressing need for standardization, calibration protocols, quality control and quantitative assessment. We have designed a new calibration imaging slide (Cancer Imaging Slide), specifically to measure the characteristics of old or new imaging systems or scanners. The layout of the slide consists of 138 boxes with the side length of 1.6 mm, containing objects of known morphologic and photometric characteristics. Among them, 112 boxes contain different permutations of circles, ovals, and squares. The circles have different radii, radius/pitch ratios and step transmissions. The ovals have different sizes and orientations. The squares are consistent in size and orientation but have different step transmission values. Also, 16 boxes contain three resolution test targets: crosses, USAF target and Siemens star. The last 10 boxes are blank boxes with different transmission values. Four slides were scanned and imaged on one commercial whole-slide scanner and one high resolution imaging system. After segmenting the images, about 200 features (photometric, morphologic and architectural) were measured with our in-house image processing software. The objective of the project is to develop a statistical process control using this new slide. In this paper, we describe the characteristics of the slide and present our preliminary results.

Sheikhzadeh, Fahime; Ye, Qian; Zulkafly, Nasir; Carraro, Anita; Korbelic, Jagoda; Chen, Zhaoyang; Harrison, Alan; Follen, Michele; MacAulay, Calum; Ward, Rabab K.; Guillaud, Martial



Quantitative orientation-independent differential interference contrast (DIC) microscopy  

NASA Astrophysics Data System (ADS)

We describe a new DIC technique, which records phase gradients within microscopic specimens independently of their orientation. The proposed system allows the generation of images representing the distribution of dry mass (optical path difference) in the specimen. Unlike in other forms of interference microscopes, this approach does not require a narrow illuminating cone. The orientation-independent differential interference contrast (OI-DIC) system can also be combined with orientation-independent polarization (OI-Pol) measurements to yield two complementary images: one showing dry mass distribution (which is proportional to refractive index) and the other showing distribution of birefringence (due to structural or internal anisotropy). With a model specimen used for this work -- living spermatocytes from the crane fly, Nephrotoma suturalis --- the OI-DIC image clearly reveals the detailed shape of the chromosomes while the polarization image quantitatively depicts the distribution of the birefringent microtubules in the spindle, both without any need for staining or other modifications of the cell. We present examples of a pseudo-color combined image incorporating both orientation-independent DIC and polarization images of a spermatocyte at diakinesis and metaphase of meiosis I. Those images provide clear evidence that the proposed technique can reveal fine architecture and molecular organization in live cells without perturbation associated with staining or fluorescent labeling. The phase image was obtained using optics having a numerical aperture 1.4, thus achieving a level of resolution never before achieved with any interference microscope.

Shribak, Michael; LaFountain, James; Biggs, David; Inoué, Shinya



Quantitative phase microscopy of red blood cells with slightly-off-axis interference  

Microsoft Academic Search

Microscopic interferometry is a noncontact technique for quantitative phase imaging of live cells. The method combines the principles of single-shot slightly-off-axis interferometry and confocal microscopy and is characterized by real-time acquisition capabilities and optimized spatial resolution. However, slightly-off-axis interferometry requires less detector bandwidth than traditional off-axis interferometry and fewer phase-shifted steps than on-axis interferometry. Meanwhile, confocal microscopy allows microstructure magnification

Liang Xue; Jian-Cheng Lai; Zhen-Hua Li



Correlative super-resolution fluorescence and electron microscopy of the nuclear pore complex with molecular resolution.  


Here, we combine super-resolution fluorescence localization microscopy with scanning electron microscopy to map the position of proteins of nuclear pore complexes in isolated Xenopus laevis oocyte nuclear envelopes with molecular resolution in both imaging modes. We use the periodic molecular structure of the nuclear pore complex to superimpose direct stochastic optical reconstruction microscopy images with a precision of <20?nm on electron micrographs. The correlative images demonstrate quantitative molecular labeling and localization of nuclear pore complex proteins by standard immunocytochemistry with primary and secondary antibodies and reveal that the nuclear pore complex is composed of eight gp210 (also known as NUP210) protein homodimers. In addition, we find subpopulations of nuclear pore complexes with ninefold symmetry, which are found occasionally among the more typical eightfold symmetrical structures. PMID:25146397

Löschberger, Anna; Franke, Christian; Krohne, Georg; van de Linde, Sebastian; Sauer, Markus



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

PubMed Central

Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3?nm, sufficient to identify the locations of individual EGFR dimer subunits. The sizes and distribution of dimers and higher order clusters of EGFRs were determined. The distance between labels bound to dimers amounted to 19?nm, consistent with a molecular model. A fraction of the EGFRs was found in higher order clusters with sizes ranging from 32–56?nm. ESEM can be used for quantitative whole cell screening studies of membrane receptors, and for the study of nanoparticle-cell interactions in general. PMID:24022088

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



Correlative microscopy: bridging the gap between fluorescence light microscopy and cryo-electron tomography.  


Cryo-electron tomography of frozen-hydrated biological samples offers a means of studying large and complex cellular structures in three-dimensions and with nanometer-scale resolution. The low contrast of unstained biological material embedded in amorphous ice and the need to minimise the exposure of these radiation-sensitive samples to the electron beam result in a poor signal-to-noise ratio. This poses problems not only in the visualisation and interpretation of such tomograms, it is also a problem in surveying the sample and in finding regions which contain the features of interest and which are suitable for recording tomograms. To address this problem, we have developed a correlative fluorescence light microscopy-electron microscopy approach, which guides the search for the structures of interest and allows electron microscopy to zoom in on them. With our approach, the total dose spent on locating regions of interest is negligible. A newly designed cryo-holder allows imaging of fluorescently labelled samples after vitrification. The absolute coordinates of structures identified and located by cryo-light microscopy are transferred to the electron microscope via a Matlab-based user interface. We have successfully tested the experimental setup and the whole procedure with two types of adherent fluorescently labelled cells, a neuronal cell line and keratinocytes, both grown directly on EM grids. PMID:17884579

Sartori, Anna; Gatz, Rudolf; Beck, Florian; Rigort, Alexander; Baumeister, Wolfgang; Plitzko, Juergen M



Quantitative phase microscopy of articular chondrocyte dynamics by wide-field digital interferometry  

PubMed Central

We experimentally implement label-free phase microscopy using wide-field digital interferometry (WFDI) techniques to retrieve quantitative volumetric data of articular chondrocyte dynamics. Using the scanless interferometric system, we visualize chondrocyte swelling and bursting induced by hypo-osmotic pressure. Reconstructed images are obtained by an efficient digital process. We use the resulting images to calculate quantitative temporal-spatial morphological parameters of the cell, with the observed dynamics limited only by the true frame rate of the camera. To show the utility of WFDI in recording articular chondrocyte dynamics, we also provide an experimental comparison of WFDI and differential interference contrast microscopy. PMID:20210420

Shaked, Natan T.; Finan, John D.; Guilak, Farshid; Wax, Adam



Quantitative imaging of cellular adhesion by total internal reflection holographic microscopy.  


Total internal reflection (TIR) holographic microscopy uses a prism in TIR as a near-field imager to perform quantitative phase microscopy of cell-substrate interfaces. The presence of microscopic organisms, cell-substrate interfaces, adhesions, and tissue structures on the prism's TIR face causes relative index of refraction and frustrated TIR to modulate the object beam's evanescent wave phase front. We present quantitative phase images of test specimens such as Amoeba proteus and cells such as SKOV-3 and 3T3 fibroblasts. PMID:19956284

Ash, William M; Krzewina, Leo; Kim, Myung K



Scanning electron microscopy of bacteria Tetrasphaera duodecadis.  


This study reports the characterization of the Tetrasphaera duodecadis bacteria and the techniques used therein. In order to evaluate the morphological characteristics of the T. duodecadis bacteria scanning electron microscope (SEM) was used throughout its different growth stages. These microorganisms were grown in vitamin B12 broths with 1% tryptone, 0.2% yeast extract, and 0.1% glucose. The turbidimetric method was employed for the determination of bacterial concentration and growth curve. The SEM results show small agglomerates of 0.8?±?0.05?µm during the lag phase, and rod-like shapes during the exponential phase with similar shapes in the stationary phase. PMID:25156672

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



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 cryo-electron microscopy methods providing imaging in the close-to-natural hydrated state. In situ, we observed an irreversible transformation of bacterial extracellular polymers during the traditional dehydration-based sample preparation that resulted in the collapse of hydrated gel-like EPS 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, Alice; Marshall, Matthew J.; Arey, Bruce W.; Williams, Kenneth H.; Buck, Edgar C.; Fredrickson, Jim K.



Scanning electron microscopy of dental calculus.  


The morphologic structure of anorganic dental calculus was studied by means of the scanning electron microscope. From surface observations, calculus is apparently composed of two components with distinguishable patters of calcification. One component is formed by the precipitation of minute calcific crystals on microorganisms and intermicrobial substances (plaque matrix). Such calcified masses, often spherical in shape, have a sponge-like appearance with empty spaces representing the former sites of entombed and degenerated organisms. Thus, intracellular calcification is not evident at this stage of calculus development. The other component, although having at least one common calcification front with the former, does not appear to be directly associated with microbial calcification. It exhibits a configuration of generally larger crystal growths of varying shapes and sizes. These two calcification patterns are comparable, both in distribution and size, to what has been observed by means of the transmission electron microscope, and what Schroeder has designated as "types A & B centers of mineralization," respectively. The calcific precipitation in type A centers have been identified by X-ray diffraction as hydroxyapatite. It is, therefore, speculated that the crystal patters in type B centers might represent other known forms of calcium phosphates present in calculus, such as octacalcium phosphate, whitlockite and brushite. PMID:953792

Lustmann, J; Lewin-Epstein, J; Shteyer, A




Microsoft Academic Search

The Auger electron spectrum was measured, using an electron spectrometer mounted in a scanning electron microscope (SEM). The shift in the energy of a differentiated carbon and oxygen Auger electron peak was measured as a function of an applied potential on the surface of a specimen. The accuracy of the potential measurements is shown to be quite insensitive to transverse

N. C. MacDonald



Quantitative x-ray differential-interference-contrast microscopy with independently adjustable bias and shear  

SciTech Connect

We present a quantitative x-ray phase imaging method that can be readily implemented on existing x-ray microscopy facilities. This technique utilizes Fresnel zone plates both as imaging optical elements for magnification and as second-order grating structures for phase-shifting interferometry. By making high-resolution quantitative x-ray phase information widely available, we expect this work to have significant impact on nanoscale biological and material studies.

Nakamura, Takashi [School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Chang Chang [School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)



Quantitative x-ray differential-interference-contrast microscopy with independently adjustable bias and shear  

Microsoft Academic Search

We present a quantitative x-ray phase imaging method that can be readily implemented on existing x-ray microscopy facilities. This technique utilizes Fresnel zone plates both as imaging optical elements for magnification and as second-order grating structures for phase-shifting interferometry. By making high-resolution quantitative x-ray phase information widely available, we expect this work to have significant impact on nanoscale biological and

Takashi Nakamura; Chang Chang



Quantitative phase microscopy: a new tool for measurement of cell culture growth and confluency in situ  

Microsoft Academic Search

Quantitative phase microscopy (QPM) is a recently developed computational approach that provides quantitative phase measurements of specimen images obtained under bright-field conditions without phase- or interference-contrast optics. To perform QPM, an in-focus bright-field image is acquired, together with one positive and one negative de-focus image. An algorithm is then applied to produce a specimen phase map. In this investigation we

Claire L. Curl; Trudi Harris; Peter J. Harris; Brendan E. Allman; Catherine J. Bellair; Alastair G. Stewart; Lea M. D. Delbridge



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



Studying Arabidopsis chloroplast structural organisation using transmission electron microscopy.  


Chloroplasts, as well as other, non-photosynthetic types of plastid, are characteristic structures within plant cells. They are relatively large organelles (typically 1-5 ?m in diameter), and so can readily be analysed by electron microscopy. Chloroplast structure is remarkably complex, comprising at least six distinct sub-organellar compartments, and is sensitive to developmental changes, environmental effects, and genetic lesions. Transmission electron microscopy (TEM), therefore, represents a powerful technique for monitoring the effects of various changing parameters or treatments on the development and differentiation of these important organelles. We describe a method for the analysis of Arabidopsis plant material by TEM, primarily for the assessment of plastid ultrastructure. PMID:21822836

Hyman, Stefan; Jarvis, R Paul



Studies of epidermal lipids using electron microscopy.  


Ruthenium tetroxide fixation has permitted the electron microscopic visualization of intercellular lipid lamellae in thin sections of stratum corneum. This development complements prior freeze-fracture studies of lipid lamellae and has advanced our knowledge about the ultrastructure of epidermal lipids in several ways. We have demonstrated a continuous lipid envelope that surrounds each differentiated stratum corneum cell and the presence of lipid lamellae throughout the entire stratum corneum of three mammalian species, including humans. Wherever lamellae are seen, they are present in multiples of one, two, or more pairs of bilayers, consistent with their formation from fused, flattened lipid vesicles. A unique pattern of lipid monolayers intervening between each pair of bilayers, based on sharing lipid chains between bilayers, has been proposed. In regions where there are no intercellular lamellae between corneocytes, intervening monolayers are in contact with adjacent lipid envelopes that might be involved in stratum corneum cohesion. However, limitations to the ruthenium technique must be overcome before changes in lamellar patterns can be accurately attributed to, or correlated with, changes in permeability brought about by experimental procedures or in diseased states. PMID:1498019

Swartzendruber, D C



Electron Microscopy of Nephropathia Epidemica. Glomerular changes.  


Electron microscopical changes in the glomeruli in 20 kidney biopsies from 18 patients, who were suffering from or had lately suffered from Nephropathia epidemica were studied. Various kinds of deposits were seen. Under the endothelial cells there were collections of light flocculent material. Small dark deposits were seen in the mesangium at the mesangial cell processes, inside the thickened basement membrane, and occasionally on the epithelial side of the membrane. Large deposits were seen around mesangial cells in the mesangium. Deposits were less numerous than in chronic immune complex diseases. The intramembranous or subepithelial deposits were associated with "moon craters", membranous convoluted structures or membrane debris. Granular extracellular mesangial material, round extracellular particles and intraendothelial microtubular inclusions were occasionally seen. In two of our cases occasional capsular epithelial cells showed numerous myelin bodies. Typical viruses were not seen in the glomeruli. The findings are in accord with the short period of scanty immune complex deposition in the glomeruli in the clinically active phase of Nephropathia epidemica. PMID:205038

Collan, Y; Lähdevirta, J; Jokinen, E J



Attosecond electron pulses for 4D diffraction and microscopy  

PubMed Central

In this contribution, we consider the advancement of ultrafast electron diffraction and microscopy to cover the attosecond time domain. The concept is centered on the compression of femtosecond electron packets to trains of 15-attosecond pulses by the use of the ponderomotive force in synthesized gratings of optical fields. Such attosecond electron pulses are significantly shorter than those achievable with extreme UV light sources near 25 nm (?50 eV) and have the potential for applications in the visualization of ultrafast electron dynamics, especially of atomic structures, clusters of atoms, and some materials. PMID:18000040

Baum, Peter; Zewail, Ahmed H.



A novel approach for correlative light electron microscopy analysis.  


Correlative light and electron microscopy (CLEM) is a multimodal technique of increasing utilization in functional, biochemical, and molecular biology. CLEM attempts to combine multidimensional information from the complementary fluorescence light microscopy (FLM) and electron microscopy (EM) techniques to bridge the various resolution gaps. Within this approach the very same cell/structure/event observed at level can be analyzed as well by FLM and EM. Unfortunately, these studies turned out to be extremely time consuming and are not suitable for statistical relevant data. Here, we describe a new CLEM method based on a robust specimen preparation protocol, optimized for cryosections (Tokuyasu method) and on an innovative image processing toolbox for a novel type of multimodal analysis. Main advantages obtained using the proposed CLEM method are: (1) hundred times more cells/structures/events that can be correlated in each single microscopy session; (2) three-dimensional correlation between FLM and EM, obtained by means of ribbons of serial cryosections and electron tomography microscopy (ETM); (3) high rate of success for each CLEM experiment, obtained implementing protection of samples from physical damage and from loss of fluorescence; (4) compatibility with the classical immunogold and immunofluorescence labeling techniques. This method has been successfully validated for the correlative analysis of Russel Bodies subcellular compartments. PMID:19725102

Vicidomini, Giuseppe; Gagliani, Maria C; Cortese, Katia; Krieger, Jens; Buescher, Peter; Bianchini, Paolo; Boccacci, Patrizia; Tacchetti, Carlo; Diaspro, Alberto



Laboratory-based quantitative hard x-ray phase microscopy in one dimension using waveguides  

NASA Astrophysics Data System (ADS)

We report on the quantitative hard x-ray phase microscopy obtained with a laboratory source equipped with an x-ray planar waveguide. The waveguide, acting as a small secondary source with increased coherence, allows for phase contrast microscopy to be measured from a phase-only one-dimensional object. We analyzed different strategies and their performances for the case studied of low absorbing one-dimensional sample. It was found that the phase-only approximation for the sample enables the best performance in phase retrieval. Results obtained from experimental data are supported by phase retrieval performed on simulated data allowing an estimation of the performance of the algorithms. The ability to perform quantitative phase contrast microscopy with waveguides is an important advance for this novel x-ray phase contrast method, well suited to compact laboratory setups.

Roberts, Matthew D.; Pelliccia, Daniele



Scanning electron microscopy imaging of hydraulic cement microstructure  

E-print Network

Scanning electron microscopy imaging of hydraulic cement microstructure by Paul Stutzman Building Reprinted from Cement and Concrete Composites, Vol. 26, No. 8, 957-966 pp., November 2004. NOTE: This paper;Available online at SCIENCE@OIRECT@ Cement & Concrete CompositesELSEVIER Cement

Bentz, Dale P.


Frontiers in Electron Microscopy: Probing the Nanoscale in Nanoseconds  

Microsoft Academic Search

Electron microscopy has traditionally been driven by the desire to investigate the result of a given materials process (e.g. nucleation and growth, fatigue etc) at the highest spatial resolution. However, this type of observation typically gives no indication as to how the material achieved its final state. With the nanotechnology revolution highlighting the novel properties that can be achieved by

Nigel Browning



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.



Seeing Inside Materials by Aberration-Corrected Electron Microscopy  

SciTech Connect

The motivation for aberration correction in electron microscopy was primarily to improve lateral resolution, and its successful achievement enabled the direct imaging of sub- ngstrom lattice spacings in a crystal. However, the smaller probe results in greatly enhanced sensitivity for imaging individual atoms, and in addition, the wider useable aperture results in a smaller depth of field.

Pennycook, Stephen J [ORNL; Borisevich, Albina Y [ORNL; van Benthem, Klaus [ORNL; Oxley, Mark P [ORNL; Luo, Weidong [ORNL; Oh, Sang Ho [ORNL; Kumar, Dhananjay [ORNL; Werner, P [Max Planck Institute of Microstructure Physics; Zakharov, N. D. [Max Planck Institute of Microstructure Physics; Molina Rubio, Sergio I [ORNL; Marinopulos, Apostolos [Vanderbilt University; Pantelides, Sokrates T [ORNL



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



PREFACE: Electron Microscopy and Analysis Group Conference 2009  

Microsoft Academic Search

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

Richard Baker



Araldite as an Embedding Medium for Electron Microscopy  

Microsoft Academic Search

Epoxy resins are suitable media for embedding for electron microscopy, as they set uniformly with virtually no shrinkage. A mixture of araldite epoxy resins has been developed which is soluble in ethanol, and which yields a block of the required hardness for thin sectioning. The critical modifications to the conven- tional mixtures are the choice of a plasticized resin in




Electron diffraction and microscopy study of nanotubes and nanowires  

Microsoft Academic Search

Carbon nanotubes have many excellent properties that are strongly influenced by their atomic structure. The realization of the ultimate potential of carbon nanotubes in technological applications necessitates a precise control of the structure of as-grown nanotubes as well as the identification of their atomic structures. Transmission electron microscopy (TEM) is a technique that can deliver this by combining the high

Hakan Deniz



Refining Mitochondria Segmentation in Electron Microscopy Imagery with Active Surfaces  

E-print Network

Refining Mitochondria Segmentation in Electron Microscopy Imagery with Active Surfaces Anne Jorstad for refining the boundary surfaces of mitochondria segmentation data. We exploit the fact that mitochondria imagery. Our resulting surfaces are seen to fit very accurately to the mitochondria membranes, more

Fua, Pascal



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



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



Breaking resolution limits in ultrafast electron diffraction and microscopy  

PubMed Central

Ultrafast electron microscopy and diffraction are powerful techniques for the study of the time-resolved structures of molecules, materials, and biological systems. Central to these approaches is the use of ultrafast coherent electron packets. The electron pulses typically have an energy of 30 keV for diffraction and 100–200 keV for microscopy, corresponding to speeds of 33–70% of the speed of light. Although the spatial resolution can reach the atomic scale, the temporal resolution is limited by the pulse width and by the difference in group velocities of electrons and the light used to initiate the dynamical change. In this contribution, we introduce the concept of tilted optical pulses into diffraction and imaging techniques and demonstrate the methodology experimentally. These advances allow us to reach limits of time resolution down to regimes of a few femtoseconds and, possibly, attoseconds. With tilted pulses, every part of the sample is excited at precisely the same time as when the electrons arrive at the specimen. Here, this approach is demonstrated for the most unfavorable case of ultrafast crystallography. We also present a method for measuring the duration of electron packets by autocorrelating electron pulses in free space and without streaking, and we discuss the potential of tilting the electron pulses themselves for applications in domains involving nuclear and electron motions. PMID:17056711

Baum, Peter; Zewail, Ahmed H.



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



Use of Atomic Force Microscopy and Transmission Electron Microscopy for Correlative Studies of Bacterial Capsules? †  

PubMed Central

Bacteria can possess an outermost assembly of polysaccharide molecules, a capsule, which is attached to their cell wall. We have used two complementary, high-resolution microscopy techniques, atomic force microscopy (AFM) and transmission electron microscopy (TEM), to study bacterial capsules of four different gram-negative bacterial strains: Escherichia coli K30, Pseudomonas aeruginosa FRD1, Shewanella oneidensis MR-4, and Geobacter sulfurreducens PCA. TEM analysis of bacterial cells using different preparative techniques (whole-cell mounts, conventional embeddings, and freeze-substitution) revealed capsules for some but not all of the strains. In contrast, the use of AFM allowed the unambiguous identification of the presence of capsules on all strains used in the present study, including those that were shown by TEM to be not encapsulated. In addition, the use of AFM phase imaging allowed the visualization of the bacterial cell within the capsule, with a depth sensitivity that decreased with increasing tapping frequency. PMID:18606791

Stukalov, Oleg; Korenevsky, Anton; Beveridge, Terry J.; Dutcher, John R.



Environmental scanning electron microscopy gold immunolabeling in cell biology.  


Immunogold labeling (IGL) technique has been utilized by many authors in combination with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to obtain the identification/localization of receptors and antigens, both in cells and tissues. Environmental scanning electron microscopy (ESEM) represents an important tool in biomedical research, since it does not require any severe processing of the sample, lowering the risk of generating artifacts and interfere with the IGL procedure. The absence of metal coating could yield further advantages for our purpose as the labeling detection is based on the atomic number difference between nanogold spheres and the biological material. Using the gaseous secondary electron detector, compositional contrast is easily revealed by the backscattered electron component of the signal. In spite of this fact, only few published papers present a combination of ESEM and IGL. Hereby we present our method, optimized to improve the intensity and the specificity of the labeling signal, in order to obtain a semiquantitative evaluation of the labeling signal.In particular, we used a combination of IGL and ESEM to detect the presence of a protein on the cell surface. To achieve this purpose, we chose as an experimental system 3T3 Swiss albino mouse fibroblasts and galectin-3. PMID:23027021

Rosso, Francesco; Papale, Ferdinando; Barbarisi, Alfonso



Electron microscopy of trypanosomes--a historical view.  


Since the discovery of the electron microscope and the development of the initial techniques for the processing of biological samples for electron microscopy, the protozoan Trypanosoma cruzi has been the subject of intense investigation. This review analyzes the results obtained by observation of whole trypanosomes as well as thin sections and replicas using several microscopic approaches. Micrographs detailing the appearance of T. cruzi using several methods illustrate the evolution of electron microscopic techniques as well as its contribution to understanding the structural organization of the protozoan. PMID:18660983

Souza, Wanderley de



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. PMID:19915208

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



Imaging and microanalysis of thin ionomer layers by scanning transmission electron microscopy  

SciTech Connect

Improved conditions for imaging and spectroscopic mapping of thin perfluorosulfonic acid (PFSA) ionomer layers in fuel cell electrodes by scanning transmission electron microscopy (STEM) have been investigated. These conditions are first identified on model systems of Nafion ionomer-coated nanostructured thin films and nanoporous Si. The optimized conditions are then applied in a quantitative study of the ionomer through-layer loading for two typical electrode catalyst coatings using electron energy loss and energy dispersive X-ray spectroscopy in the transmission electron microscope. The e-beam induced damage to the perfluorosulfonic acid (PFSA) ionomer is quantified by following the fluorine mass loss with electron exposure and is then mitigated by a few orders of magnitude using cryogenic specimen cooling and a higher incident electron voltage. Multivariate statistical analysis is also applied to the analysis of spectrum images for data denoising and unbiased separation of independent components related to the catalyst, ionomer, and support.

Cullen, David A [ORNL; Koestner, Roland [General Motors Corporation; Kukreja, Ratan [General Motors Corporation; Minko, Sergiy [Clarkson University, Potsdam, NY; Trotsenko, Oleksandr [Clarkson University, Potsdam, NY; Tokarev, Alexander V [ORNL; Guetaz, Laure [French Atomic Energy Commission (CEA), Grenoble; Meyer III, Harry M [ORNL; Parish, Chad M [ORNL; More, Karren Leslie [ORNL



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. PMID:19348881

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



Biological imaging with 4D ultrafast electron microscopy  

PubMed Central

Advances in the imaging of biological structures with transmission electron microscopy continue to reveal information at the nanometer length scale and below. The images obtained are static, i.e., time-averaged over seconds, and the weak contrast is usually enhanced through sophisticated specimen preparation techniques and/or improvements in electron optics and methodologies. Here we report the application of the technique of photon-induced near-field electron microscopy (PINEM) to imaging of biological specimens with femtosecond (fs) temporal resolution. In PINEM, the biological structure is exposed to single-electron packets and simultaneously irradiated with fs laser pulses that are coincident with the electron pulses in space and time. By electron energy-filtering those electrons that gained photon energies, the contrast is enhanced only at the surface of the structures involved. This method is demonstrated here in imaging of protein vesicles and whole cells of Escherichia coli, both are not absorbing the photon energy, and both are of low-Z contrast. It is also shown that the spatial location of contrast enhancement can be controlled via laser polarization, time resolution, and tomographic tilting. The high-magnification PINEM imaging provides the nanometer scale and the fs temporal resolution. The potential of applications is discussed and includes the study of antibodies and immunolabeling within the cell. PMID:20479261

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



Robert Feulgen Prize Lecture 1995. Electronic light microscopy: present capabilities and future prospects.  


Electronic light microscopy involves the combination of microscopic techniques with electronic imaging and digital image processing, resulting in dramatic improvements in image quality and ease of quantitative analysis. In this review, after a brief definition of digital images and a discussion of the sampling requirements for the accurate digital recording of optical images, I discuss the three most important imaging modalities in electronic light microscopy--video-enhanced contrast microscopy, digital fluorescence microscopy and confocal scanning microscopy--considering their capabilities, their applications, and recent developments that will increase their potential. Video-enhanced contrast microscopy permits the clear visualisation and real-time dynamic recording of minute objects such as microtubules, vesicles and colloidal gold particles, an order of magnitude smaller than the resolution limit of the light microscope. It has revolutionised the study of cellular motility, and permits the quantitative tracking of organelles and gold-labelled membrane bound proteins. In combination with the technique of optical trapping (optical tweezers), it permits exquisitely sensitive force and distance measurements to be made on motor proteins. Digital fluorescence microscopy enables low-light-level imaging of fluorescently labelled specimens. Recent progress has involved improvements in cameras, fluorescent probes and fluorescent filter sets, particularly multiple bandpass dichroic mirrors, and developments in multiparameter imaging, which is becoming particularly important for in situ hybridisation studies and automated image cytometry, fluorescence ratio imaging, and time-resolved fluorescence. As software improves and small computers become more powerful, computational techniques for out-of-focus blur deconvolution and image restoration are becoming increasingly important. Confocal microscopy permits convenient, high-resolution, non-invasive, blur-free optical sectioning and 3D image acquisition, but suffers from a number of limitations. I discuss advances in confocal techniques that address the problems of temporal resolution, spherical and chromatic aberration, wavelength flexibility and cross-talk between fluorescent channels, and describe new optics to enhance axial resolution and the use of two-photon excitation to reduce photobleaching. Finally, I consider the desirability of establishing a digital image database, the BioImage database, which would permit the archival storage of, and public Internet access to, multidimensional image data from all forms of biological microscopy. Submission of images to the BioImage database would be made in coordination with the scientific publication of research results based upon these data.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8536077

Shotton, D M



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


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



Digital self-referencing quantitative phase microscopy by wavefront folding in holographic image reconstruction.  


A completely numerical method, named digital self-referencing holography, is described to easily accomplish a quantitative phase microscopy for microfluidic devices by a digital holographic microscope. The approach works through an appropriate numerical manipulation of the retrieved complex wavefront. The self-referencing is obtained by folding the retrieved wavefront in the image plane. The folding operation allows us to obtain the correct phase map by subtracting from the complex region of interest a flat area outside the microfluidic channel. To demonstrate the effectiveness of the method, quantitative phase maps of bovine spermatozoa and in vitro cells are retrieved. PMID:20967076

Coppola, G; Di Caprio, G; Gioffré, M; Puglisi, R; Balduzzi, D; Galli, A; Miccio, L; Paturzo, M; Grilli, S; Finizio, A; Ferraro, P



Shift-variant digital holographic microscopy: inaccuracies in quantitative phase imaging.  


Inaccuracies introduced in quantitative phase digital holographic microscopy by the use of nontelecentric imaging systems are analyzed. Computer modeling of the experimental result shows that even negligible errors in the radius and center of curvature of the numerical compensation needed to get rid of the remaining quadratic phase factor introduce errors in the phase measurements; these errors depend on the position of the object in the field-of-view. However, when a telecentric imaging system is utilized for the recording of the holograms, the numerical modeling and experimental results show the shift-invariant behavior of the quantitative-phase digital holographic microscope. PMID:23595482

Doblas, Ana; Sánchez-Ortiga, Emilio; Martínez-Corral, Manuel; Saavedra, Genaro; Andrés, Pedro; Garcia-Sucerquia, Jorge



Vibrational and optical spectroscopies integrated with environmental transmission electron microscopy.  


Here, we present a measurement platform for collecting multiple types of spectroscopy data during high-resolution environmental transmission electron microscopy observations of dynamic processes. Such coupled measurements are made possible by a broadband, high-efficiency, free-space optical system. The critical element of the system is a parabolic mirror, inserted using an independent hollow rod and placed below the sample holder which can focus a light on the sample and/or collect the optical response. We demonstrate the versatility of this optical setup by using it to combine in situ atomic-scale electron microscopy observations with Raman spectroscopy. The Raman data is also used to measure the local temperature of the observed sample area. Other applications include, but are not limited to: cathodo- and photoluminescence spectroscopy, and use of the laser as a local, high-rate heating source. PMID:25490533

Picher, Matthieu; Mazzucco, Stefano; Blankenship, Steve; Sharma, Renu



Microfabricated high-bandpass foucault aperture for electron microscopy  


A variant of the Foucault (knife-edge) aperture is disclosed that is designed to provide single-sideband (SSB) contrast at low spatial frequencies but retain conventional double-sideband (DSB) contrast at high spatial frequencies in transmission electron microscopy. The aperture includes a plate with an inner open area, a support extending from the plate at an edge of the open area, a half-circle feature mounted on the support and located at the center of the aperture open area. The radius of the half-circle portion of reciprocal space that is blocked by the aperture can be varied to suit the needs of electron microscopy investigation. The aperture is fabricated from conductive material which is preferably non-oxidizing, such as gold, for example.

Glaeser, Robert; Cambie, Rossana; Jin, Jian



Maximum likelihood refinement of electron microscopy data with normalization errors  

PubMed Central

Commonly employed data models for maximum likelihood refinement of electron microscopy images behave poorly in the presence of normalization errors. Small variations in background mean or signal brightness are relatively common in cryo-electron microscopy data, and varying signal-to-noise ratios or artifacts in the images interfere with standard normalization procedures. In this paper, a statistical data model that accounts for normalization errors is presented, and a corresponding algorithm for maximum likelihood classification of structurally heterogeneous projection data is derived. The extended data model has general relevance, since similar algorithms may be derived for other maximum likelihood approaches in the field. The potentials of this approach are illustrated for two structurally heterogeneous data sets: 70S E.coli ribosomes and human RNA polymerase II complexes. In both cases, maximum likelihood classification based on the conventional data model failed, whereas the new approach was capable of revealing previously unobserved conformations. PMID:19236920

Scheres, Sjors H.W.; Valle, Mikel; Grob, Patricia; Nogales, Eva; Carazo, José-María



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


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



New Tools for Comparing Microscopy Images: Quantitative Analysis of Cell Types in Bacillus subtilis.  


Fluorescence microscopy is a method commonly used to examine individual differences between bacterial cells, yet many studies still lack a quantitative analysis of fluorescence microscopy data. Here we introduce some simple tools that microbiologists can use to analyze and compare their microscopy images. We show how image data can be converted to distribution data. These data can be subjected to a cluster analysis that makes it possible to objectively compare microscopy images. The distribution data can further be analyzed using distribution fitting. We illustrate our methods by scrutinizing two independently acquired data sets, each containing microscopy images of a doubly labeled Bacillus subtilis strain. For the first data set, we examined the expression of srfA and tapA, two genes which are expressed in surfactin-producing and matrix-producing cells, respectively. For the second data set, we examined the expression of eps and tapA; these genes are expressed in matrix-producing cells. We show that srfA is expressed by all cells in the population, a finding which contrasts with a previously reported bimodal distribution of srfA expression. In addition, we show that eps and tapA do not always have the same expression profiles, despite being expressed in the same cell type: both operons are expressed in cell chains, while single cells mainly express eps. These findings exemplify that the quantification and comparison of microscopy data can yield insights that otherwise would go unnoticed. PMID:25448819

van Gestel, Jordi; Vlamakis, Hera; Kolter, Roberto



Defects characterization of welded specimens by transmission electron microscopy  

Microsoft Academic Search

Austenitic Type 304L stainless steel (SS) and martensitic Alloy EP-823 have been identified as candidate structural materials to contain spallation target for transmutation of nuclear waste. Welded specimens consisting of either or both materials have been evaluated by transmission electron microscopy (TEM) to determine the dislocation density near the heat-affected-zone (HAZ) and the base material. The results indicate that the

A. K. Roy; S. Chanda; A. Ghosh; P. Kumar; L. Mab



Visualization of neural cell adhesion molecule by electron microscopy  

Microsoft Academic Search

The 130- and 160-kD polypeptide forms of the neural cell adhesion molecule (NCAM) were ana- lyzed 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. Ag- gregates were also present, containing two to six rods in a pinwheel-like configuration without

Alison K. Hall; Urs Rutishauser



Quantitative phase imaging microscopy with multi-wavelength optical phase unwrapping  

Microsoft Academic Search

This dissertation presents a quantitative phase imaging microscopy technique that combines phase-shifting interferometry with multi-wavelength optical phase unwrapping. The technique consists of a Michelson-type interferometer illuminated with any of three types of light sources; light emitting diodes, laser diodes and a ring dye laser. Interference images are obtained by using a 4-frame phase shifting method, and are combined to calculate

Nilanthi Warnasooriya



Quantitative Phase and Amplitude Imaging Using Differential-Interference Contrast (DIC) Microscopy  

Microsoft Academic Search

We present an extension of the development of an alternating minimization (AM) method1 for the computation of a specimen's complex transmittance function (magnitude and phase) from DIC images. The ability to extract both quantitative phase and amplitude information from two rotationally-diverse DIC images (i.e., acquired by rotating the sample) extends previous efforts in computational DIC microscopy that have focused on

Chrysanthe Preza; Joseph A. O'Sullivan


Three-dimensional volume imaging with electron microscopy toward connectome.  


Ultrastructural analyses with electron microscopy have provided indispensable information to understand physiology and pathology of the nervous system. Recent advancement in imaging methodology paved the way for complete reconstruction of the neuronal connection map in the central nervous system, which is termed 'connectome' and would provide key insights to understand the functions of the brain. The critical advancement includes serial ultrastructural observation with scanning electron microscopy (SEM) instead of conventional serial sectioning transmission electron microscopy along with specific tissue preparation methods to increase heavy metal deposition for efficient SEM imaging. The advanced imaging methods using SEM have distinct advantages and disadvantages in multiple aspects, such as resolution and imaging speed, and should be selected depending on the observation conditions, such as target tissue sizes, required spatial resolution and necessity for re-observation. Dealing with the huge dataset remained to be a major obstacle, and automation in segmentation and 3D reconstruction would be critical to understand neuronal circuits in a larger volume of the brain. Future improvement in acquisition and analyses of the morphological data obtained with the advanced SEM imaging is awaited to elucidate the significance of whole connectome as the structural basis of the consciousness, intelligence and memory of a subject. PMID:25550364

Ohno, Nobuhiko; Katoh, Mitsuhiko; Saitoh, Yurika; Saitoh, Sei; Ohno, Shinichi



Sample preparation for electron microscopy of internal cell structure.  


Methods are reviewed for examination of internal cell structure by high-resolution scanning electron microscopy and compared with the rapid-freeze deep-etch replica technique used in transmission electron microscopy. Rapid freezing of fresh material, followed by freeze-fracture, provides a theoretically attractive approach in ultrastructure studies, but the high protein and solute content of most cells prevents a deep three-dimensional view for material frozen without some form of extraction. After discussion of other methods it is concluded that the most useful general approach, at least for cultured cells, is to first permeabilize or break open the cells in a medium which preserves the structure under study in a functional state as, for example, the movement of chromosomes along the division spindle, or transport of proteins within the Golgi region. After permeabilization, with attendant partial extraction, the preparation can be fixed, then viewed by either deep-etch replication, or by high-resolution scanning electron microscopy, with structure of interest revealed in deep view. PMID:1504346

Haggis, G H



A study of the odontoblast process with transmission electron microscopy.  


Freshly extracted human third molars with completely formed roots were sectioned and placed in Karnovsky's fixative. The specimens were decalcified in ethylenediaminetetraacetic acid (EDTA) for 91 days, followed by digestion in collagenase. They were then fixed in a solution of buffered osmium tetroxide or ruthenium red and buffered osmium tetroxide, embedded in Spurr's plastic mixture, and sectioned for transmission electron microscopy. Each section was stained with uranyl acetate and lead citrate and viewed with a transmission electron microscope. No odontoblast processes could be identified at the cemental third of the dentin with the described technique. PMID:2431372

White, R K; Senia, E S; Zislis, T; Fox, L T; Zeagler, J W



High Resolution Electron Microscopy Study Of Silica Aerogel Transparent Insulation  

NASA Astrophysics Data System (ADS)

The structure of silica aerogel was studied by transmission electron microscopy. The aerogel network consists of particles about 10.0 nm in diameter. The chemical composition of these aggregates was found to be a pure stoichiometric Si0; by both ESCA and Auger spectroscopy. These SiO2 groups appear to form a random network within each particle. The details of this arrangement have yet to be determined, because in this preliminary study, silica aerogel was found to transform after exposure to the intense electron beam.

Mazur, J. H.; Lampert, C. M.



Transmission Electron Microscopy Study of InN Nanorods  

SciTech Connect

InN nanorods were grown on a, c-, and r-plane of sapphire and also on Si (111) and GaN (0001) by non-catalytic, template-free hydride metal-organic vapor phase epitaxy and studied by transmission electron microscopy, electron energy loss (EELS) and photoluminescence (PL) at room temperature. These nanocrystals have different shapes and different faceting depending on the substrate used and their crystallographic orientation. EELS measurements have confirmed the high purity of these crystals. The observed PL peak was in the range of 0.9-0.95 eV. The strongest PL intensity was observed for the nanocrystals with the larger diameters.

Liliental-Weber, Z.; Li, X.; Kryliouk, Olga; Park, H.J.; Mangum,J.; Anderson, T.



Electron microscopy study of antioxidant interaction with bacterial cells  

NASA Astrophysics Data System (ADS)

To maintain native microorganisms genotype and phenotype features a lyophylization technique is widely used. However in this case cells are affected by influences of vacuum and low temperature that cause a part of the cells population to be destruction. Another factor reduced microorganisms vitality is formation of reactive oxygen forms that damage certain biological targets (such as DNA, membranes etc.) Recently to raise microorganism's resistance against adverse condition natural and synthetic antioxidants are used. Antioxidant- are antagonists of free radicals. Introduction of antioxidants in protective medium for lyophylization increase bacteria storage life about 2,0-4,8 fold in comparison with reference samples. In the article the main results of our investigation of antioxidants interaction with microorganism cells is described. As bacteria cells we use vaccine strain yersinia pestis EV, that were grown for 48 h at 28 degree(s)C on the Hottinger agar (pH 7,2). Antioxidants are inserted on the agar surface in specimen under test. To investigate a localization of antioxidants for electron microscopy investigation, thallium organic antioxidants were used. The thallium organic compounds have an antioxidant features if thallium is in low concentration (about 1(mu) g/ml). The localization of the thallium organic antioxidants on bacteria Y. pestis EV is visible in electron microscopy images, thallium being heavy metal with high electron density. The negatively stained bacteria and bacteria thin sections with thallium organic compounds were investigated by means of transmission electron microscopy. The localization of the thallium organic compounds is clearly visible in electron micrographs as small dark spots with size about 10-80nm. Probably mechanisms of interaction of antioxidants with bacteria cells are discussed.

Plotnikov, Oleg P.; Novikova, Olga V.; Konnov, Nikolai P.; Korsukov, Vladimir N.; Gunkin, Ivan F.; Volkov, Uryi P.



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. PMID:23198914

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



4D multiple-cathode ultrafast electron microscopy.  


Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging. PMID:25006261

Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H



4D multiple-cathode ultrafast electron microscopy  

PubMed Central

Four-dimensional multiple-cathode ultrafast electron microscopy is developed to enable the capture of multiple images at ultrashort time intervals for a single microscopic dynamic process. The dynamic process is initiated in the specimen by one femtosecond light pulse and probed by multiple packets of electrons generated by one UV laser pulse impinging on multiple, spatially distinct, cathode surfaces. Each packet is distinctly recorded, with timing and detector location controlled by the cathode configuration. In the first demonstration, two packets of electrons on each image frame (of the CCD) probe different times, separated by 19 picoseconds, in the evolution of the diffraction of a gold film following femtosecond heating. Future elaborations of this concept to extend its capabilities and expand the range of applications of 4D ultrafast electron microscopy are discussed. The proof-of-principle demonstration reported here provides a path toward the imaging of irreversible ultrafast phenomena of materials, and opens the door to studies involving the single-frame capture of ultrafast dynamics using single-pump/multiple-probe, embedded stroboscopic imaging. PMID:25006261

Baskin, John Spencer; Liu, Haihua; Zewail, Ahmed H.



Quantitative auger electron analysis of titanium nitrides  

Microsoft Academic Search

Chemical analysis of titanium nitrides by Auger Electron Spectroscopy is complicated by the fact that the main Auger electron emission from nitrogen occurs at an energy that completely overlaps the transition from titanium. For this reason, most surface analysis of titanium nitride has been semiquantitative, at best. In this paper, Auger spectrum simulation techniques are used to establish that satisfactory

P. T. Dawson; K. K. Tzatzov



Fast microstructure and phase analyses of nanopowders using combined analysis of transmission electron microscopy scattering patterns.  


The full quantitative characterization of nanopowders using transmission electron microscopy scattering patterns is shown. This study demonstrates the feasibility of the application of so-called combined analysis, a global approach for phase identification, structure refinement, characterization of anisotropic crystallite sizes and shapes, texture analysis and texture variations with the probed scale, using electron diffraction patterns of TiO2 and Mn3O4 nanocrystal aggregates and platinum films. Electron diffraction pattern misalignments, positioning, and slight changes from pattern to pattern are directly integrated and refined within this approach. The use of a newly developed full-pattern search-match methodology for phase identification of nanopowders and the incorporation of the two-wave dynamical correction for diffraction patterns are also reported and proved to be efficient. PMID:25176993

Boullay, P; Lutterotti, L; Chateigner, D; Sicard, L



Quantitative light and electron microscopical studies of the epithelial-connective tissue junction in intraoral mucosae.  


The present study was designed to clarify the morphological nature of epithelial-connective tissue attachment by quantitative comparison of palatal and buccal mucosae. Tissue samples were obtained from ferrets and, following a strict sampling regime, sections were obtained for quantitative light and electron microscopy. Electron micrographs from the epithelial-connective tissue junction were subjected to analysis by serological intersection counting. Quantitative results show that palatal epithelium has a comparatively convoluted interface, and is twice as thick as buccal epithelium. Stereological data are presented for relative surface area of basal plasma membrane occupied by hemidesmosomes, mean hemidesmosomal diameter and numerical density of hemidesmosomes per unit area of basal plasma membrane. Larger hemidesmosomes are found in the palatal epithelium. Results suggest that a prominent rete-ridge pattern, as seen in the palatal epithelium, along with a greater specialized surface for adhesion, may be responsible for providing epithelial-connective tissue stability in regions subjected to high mechanical stress. PMID:7143437

Bale, E; White, F H



Interference electron microscopy of one-dimensional electron-optical phase objects  

Microsoft Academic Search

The application of interference electron microscopy to the investigation of electron optical one-dimensional phase objects like reverse biased p–n junctions and ferromagnetic domain walls is considered. In particular the influence of diffraction from the biprism edges on the interference images is analyzed and the range of applicability of the geometric optical equation for the interpretation of the interference fringe shifts

P. F. Fazzini; L. Ortolani; G. Pozzi; F. Ubaldi



Digital Holographic Microscopy: Quantitative Phase Imaging and Applications in Live Cell Analysis  

NASA Astrophysics Data System (ADS)

The analysis of complex processes in living cells creates a high demand for fast and label-free methods for online monitoring. Widely used fluorescence methods require specific labeling and are often restricted to chemically fixated samples. Thus, methods that offer label-free and minimally invasive detection of live cell processes and cell state alterations are of particular interest. In combination with light microscopy, digital holography provides label-free, multi-focus quantitative phase imaging of living cells. In overview, several methods for digital holographic microscopy (DHM) are presented. First, different experimental setups for the recording of digital holograms and the modular integration of DHM into common microscopes are described. Then the numerical processing of digitally captured holograms is explained. This includes the description of spatial and temporal phase shifting techniques, spatial filtering based reconstruction, holographic autofocusing, and the evaluation of self-interference holograms. Furthermore, the usage of partial coherent light and multi-wavelength approaches is discussed. Finally, potentials of digital holographic microscopy for quantitative cell imaging are illustrated by results from selected applications. It is shown that DHM can be used for automated tracking of migrating cells and cell thickness monitoring as well as for refractive index determination of cells and particles. Moreover, the use of DHM for label-free analysis in fluidics and micro-injection monitoring is demonstrated. The results show that DHM is a highly relevant method that allows novel insights in dynamic cell biology, with applications in cancer research and for drugs and toxicity testing.

Kemper, Björn; Langehanenberg, Patrik; Kosmeier, Sebastian; Schlichthaber, Frank; Remmersmann, Christian; von Bally, Gert; Rommel, Christina; Dierker, Christian; Schnekenburger, Jürgen


Resinless section electron microscopy reveals the yeast cytoskeleton.  


The cytoskeleton of Saccharomyces cerevisiae is essentially invisible using conventional microscopy techniques. A similar problem was solved for the mammalian cell cytoskeleton using resinless section electron microscopy, a technique applied here to yeast. In the resinless image, soluble proteins are no longer cloaked by embedding medium and must be removed by selective detergent extraction. In yeast, this requires breaching the cell wall by digesting with Zymolyase sufficiently to allow detergent extraction of the plasma membrane lipids. Gel electropherograms show that the extracted or "soluble" proteins are distinct from the retained or "structural" proteins that presumably comprise the cytoskeleton. These putative cytoskeleton proteins include the major portions of a 43-kDa protein, which is presumably actin, and of proteins in a band appearing at 55 kDa, as well as numerous less abundant, nonactin proteins. Resinless section electron micrographs show a dense, three-dimensional web of anastomosing, polymorphic filaments bounded by the remnant cell wall. Although the filament network is very heterogenous, there appear to be two principal classes of filament diameters-5 nm and 15-20 nm-which may correspond to actin and intermediate filaments, respectively. A large oval region of lower filament density probably corresponds to the vacuole, and an electron dense spheroidal body, 300-500 nm in diameter, is likely the nucleus. The techniques detailed in this report afford new approaches to the study of yeast cytoarchitecture. PMID:9108046

Penman, J; Penman, S



Electron microscopy of negatively stained and unstained fibrinogen.  


Electron microscope images of negatively stained fibrinogen are predominantly asymmetric rods 450 A in length and about 60 A in width. The molecules appear to have considerable flexibility, and mass distribution along the major axis is not uniquely distinguished despite apparent beading in some particles. Scanning transmission electron microscopy of unstained fibrinogen again demonstrates that a majority of molecules are rodlike. The results differ from those obtained by negative staining in that a substantial fraction of images are trinodular with striking resemblance to those obtained by C. E. Hall and H. S. Slayter [J. Biophys. Biochem. Cytol. (1959) 5, 11--16] using the mica replica technique. The above results were obtained on glow-discharged carbon substrate films by a simple low-concentration, long-attachment-time modification of standard deposition methods that is diffusion controlled and depends on concentration and time but is independent of pH, buffer, and other staining conditions. Evidence is presented that standard attachment procedures result in artifactual images. Any models of fibrinogen in solution consequently must encompass properties that permit its visualization as an asymmetetric rod by electron microscopy as first suggested by Hall and Slayter 20 years ago. PMID:6158041

Estis, L F; Haschemeyer, R H



Interferometric time-stretch microscopy for ultrafast quantitative cellular and tissue imaging at 1 ?m  

NASA Astrophysics Data System (ADS)

Quantitative phase imaging (QPI) has been proven to be a powerful tool for label-free characterization of biological specimens. However, the imaging speed, largely limited by the image sensor technology, impedes its utility in applications where high-throughput screening and efficient big-data analysis are mandated. We here demonstrate interferometric time-stretch (iTS) microscopy for delivering ultrafast quantitative phase cellular and tissue imaging at an imaging line-scan rate >20 MHz-orders-of-magnitude faster than conventional QPI. Enabling an efficient time-stretch operation in the 1-?m wavelength window, we present an iTS microscope system for practical ultrafast QPI of fixed cells and tissue sections, as well as ultrafast flowing cells (at a flow speed of up to 8 m/s). To the best of our knowledge, this is the first time that time-stretch imaging could reveal quantitative morphological information of cells and tissues with nanometer precision. As many parameters can be further extracted from the phase and can serve as the intrinsic biomarkers for disease diagnosis, iTS microscopy could find its niche in high-throughput and high-content cellular assays (e.g., imaging flow cytometry) as well as tissue refractometric imaging (e.g., whole-slide imaging for digital pathology).

Lau, Andy K. S.; Wong, Terence T. W.; Ho, Kenneth K. Y.; Tang, Matthew T. H.; Chan, Antony C. S.; Wei, Xiaoming; Lam, Edmund Y.; Shum, Ho Cheung; Wong, Kenneth K. Y.; Tsia, Kevin K.



Interferometric time-stretch microscopy for ultrafast quantitative cellular and tissue imaging at 1 ?m.  


Quantitative phase imaging (QPI) has been proven to be a powerful tool for label-free characterization of biological specimens. However, the imaging speed, largely limited by the image sensor technology, impedes its utility in applications where high-throughput screening and efficient big-data analysis are mandated. We here demonstrate interferometric time-stretch (iTS) microscopy for delivering ultrafast quantitative phase cellular and tissue imaging at an imaging line-scan rate >20 MHz—orders-of-magnitude faster than conventional QPI. Enabling an efficient time-stretch operation in the 1-?m wavelength window, we present an iTS microscope system for practical ultrafast QPI of fixed cells and tissue sections, as well as ultrafast flowing cells (at a flow speed of up to 8 m?s). To the best of our knowledge, this is the first time that time-stretch imaging could reveal quantitative morphological information of cells and tissues with nanometer precision. As many parameters can be further extracted from the phase and can serve as the intrinsic biomarkers for disease diagnosis, iTS microscopy could find its niche in high-throughput and high-content cellular assays (e.g., imaging flow cytometry) as well as tissue refractometric imaging (e.g., whole-slide imaging for digital pathology). PMID:24983913

Lau, Andy K S; Wong, Terence T W; Ho, Kenneth K Y; Tang, Matthew T H; Chan, Antony C S; Wei, Xiaoming; Lam, Edmund Y; Shum, Ho Cheung; Wong, Kenneth K Y; Tsia, Kevin K



Imaging and quantitative data acquisition of biological cell walls with Atomic Force Microscopy and Scanning Acoustic Microscopy  

SciTech Connect

This chapter demonstrates the feasibility of Atomic Force Microscopy (AFM) and High Frequency Scanning Acoustic Microscopy (HF-SAM) as tools to characterize biological tissues. Both the AFM and the SAM have shown to provide imaging (with different resolution) and quantitative elasticity measuring abilities. Plant cell walls with minimal disturbance and under conditions of their native state have been examined with these two kinds of microscopy. After descriptions of both the SAM and AFM, their special features and the typical sample preparation is discussed. The sample preparation is focused here on epidermal peels of onion scales and celery epidermis cells which were sectioned for the AFM to visualize the inner surface (closest to the plasma membrane) of the outer epidermal wall. The nm-wide cellulose microfibrils orientation and multilayer structure were clearly observed. The microfibril orientation and alignment tend to be more organized in older scales compared with younger scales. The onion epidermis cell wall was also used as a test analog to study cell wall elasticity by the AFM nanoindentation and the SAM V(z) feature. The novelty in this work was to demonstrate the capability of these two techniques to analyze isolated, single layered plant cell walls in their natural state. AFM nanoindentation was also used to probe the effects of Ethylenediaminetetraacetic acid (EDTA), and calcium ion treatment to modify pectin networks in cell walls. The results suggest a significant modulus increase in the calcium ion treatment and a slight decrease in EDTA treatment. To complement the AFM measurements, the HF-SAM was used to obtain the V(z) signatures of the onion epidermis. These measurements were focused on documenting the effect of pectinase enzyme treatment. The results indicate a significant change in the V(z) signature curves with time into the enzyme treatment. Thus AFM and HF-SAM open the door to a systematic nondestructive structure and mechanical property study of complex biological cell walls. A unique feature of this approach is that both microscopes allow the biological samples to be examined in their natural fluid (water) environment.

Tittmann, B. R. [Penn State; Xi, X. [Penn State



Photoemission Electron Microscopy of a Plasmonic Silver Nanoparticle Trimer  

SciTech Connect

We present a combined experimental and theoretical study to investigate the spatial distribution of photoelectrons emitted from core-shell silver (Ag) nanoparticles. We use two-photon photoemission microscopy (2P-PEEM) to spatially resolve electron emission from a trimeric core-shell aggregate of triangular symmetry. Finite difference time domain (FDTD) simulations are performed to model the intensity distributions of the electromagnetic near-fields resulting from femtosecond (fs) laser excitation of localized surface plasmon oscillations in the triangular core-shell structure. We demonstrate that the predicted FDTD near-field intensity distribution reproduces the 2P-PEEM photoemission pattern.

Peppernick, Samuel J.; Joly, Alan G.; Beck, Kenneth M.; Hess, Wayne P.; Wang, Jinyong; Wang, Yi-Chung; Wei, Wei



Fast projection matching for cryo-electron microscopy image reconstruction.  


A new FFT-accelerated projection matching method is presented and tested. The electron microscopy images are represented by their Fourier-Bessel transforms and the 3D model by its expansion in spherical harmonics, or more specifically in terms of symmetry-adapted functions. The rotational and translational properties of these representations are used to quickly access all the possible 2D projections of the 3D model, which allow an exhaustive inspection of the whole five-dimensional domain of parameters associated to each particle. PMID:18353677

Estrozi, Leandro Farias; Navaza, Jorge



Electron microscopy of a Gd-Ba-Cu-O superconductor  

NASA Technical Reports Server (NTRS)

An electron microscopy study has been carried out to characterize the microstructure of a sintered Gd-Ba-Cu-O superconductor alloy. The GdBa2Cu3O(7-x) phase in the oxygen annealed sample is orthorhombic, while in the vacuum annealed sample it is tetragonal. It is shown that the details of the fine structure in the 001-line zone axis convergent beam patterns can be used to distinguish between the orthorhombic form and the tetragonal form. In addition to this matrix phase, an amorphous phase is frequently observed at the triple grain junctions. Gd-rich inclusions have been observed inside the matrix phase.

Ramesh, R.; Thomas, G.; Meng, R. L.; Hor, P. H.; Chu, C. W.



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


Confocal Microscopy for Modeling Electron Microbeam Irradiation of Skin  

SciTech Connect

For radiation exposures employing targeted sources such as particle microbeams, the deposition of energy and dose will depend on the spatial heterogeneity of the spample. Although cell structural variations are relatively minor for two-dimensional cell cultures, they can vary significantly for fully differential tissues. Employing high-resolution confocal microscopy, we have determined the spatial distribution, size, and shape of epidermal kerantinocyte nuclei for the full-thickness EpiDerm skin model (MatTek, Ashland, VA). Application of these data to claculate the microdosimetry and microdistribution of energy deposition by an electron microbeam is discussed.

Miller, John H.; Chrisler, William B.; Wang, Xihai; Sowa, Marianne B.



Simultaneous orientation and thickness mapping in transmission electron microscopy.  


In this paper we introduce an approach for simultaneous thickness and orientation mapping of crystalline samples by means of transmission electron microscopy. We show that local thickness and orientation values can be extracted from experimental dark-field (DF) image data acquired at different specimen tilts. The method has been implemented to automatically acquire the necessary data and then map thickness and crystal orientation for a given region of interest. We have applied this technique to a specimen prepared from a commercial semiconductor device, containing multiple 22nm technology transistor structures. The performance and limitations of our method are discussed and compared to those of other techniques available. PMID:25497718

Tyutyunnikov, Dmitry; Burak Özdöl, V; Koch, Christoph T



Correlative light and electron microscopy imaging of autophagy in a zebrafish infection model.  


High-resolution imaging of autophagy has been used intensively in cell culture studies, but so far it has been difficult to visualize this process in detail in whole animal models. In this study we present a versatile method for high-resolution imaging of microbial infection in zebrafish larvae by injecting pathogens into the tail fin. This allows visualization of autophagic compartments by light and electron microscopy, which makes it possible to correlate images acquired by the 2 techniques. Using this method we have studied the autophagy response against Mycobacterium marinum infection. We show that mycobacteria during the progress of infection are frequently associated with GFP-Lc3-positive vesicles, and that 2 types of GFP-Lc3-positive vesicles were observed. The majority of these vesicles were approximately 1 ?m in size and in close vicinity of bacteria, and a smaller number of GFP-Lc3-positive vesicles was larger in size and were observed to contain bacteria. Quantitative data showed that these larger vesicles occurred significantly more in leukocytes than in other cell types, and that approximately 70% of these vesicles were positive for a lysosomal marker. Using electron microscopy, it was found that approximately 5% of intracellular bacteria were present in autophagic vacuoles and that the remaining intracellular bacteria were present in phagosomes, lysosomes, free inside the cytoplasm or occurred as large aggregates. Based on correlation of light and electron microscopy images, it was shown that GFP-Lc3-positive vesicles displayed autophagic morphology. This study provides a new approach for injection of pathogens into the tail fin, which allows combined light and electron microscopy imaging in vivo and opens new research directions for studying autophagy process related to infectious diseases. PMID:25126731

Hosseini, Rohola; Lamers, Gerda Em; Hodzic, Zlatan; Meijer, Annemarie H; Schaaf, Marcel Jm; Spaink, Herman P



Quantitative Measurements of Grain Boundary Sliding in an Ultrafine-Grained Al Alloy by Atomic Force Microscopy  

NASA Astrophysics Data System (ADS)

In the current study, quantitative measurements for grain boundary sliding (GBS) in ultrafine-grained (UFG) 5083 Al by atomic force microscopy (AFM) were performed. An ion beam polishing and etching technique was used to reveal grain boundaries in the alloy for AFM characterization. A comparison between the average grain sizes measured from AFM images and those estimated from transmission electron microscopy micrographs and electron backscatter diffraction (EBSD) maps showed excellent agreement. The vertical offset of GBS was measured by comparing predeformation and postdeformation AFM images. By analyzing these measurements, the contribution of GBS to the total tensile strain in 5083 Al was estimated as 25 pct at a strain rate of 10-4 seconds-1 and a temperature of 473 K (200 °C). It was demonstrated that the relatively low value of the contribution of GBS to the total strain is most likely the result of testing UFG 5083 Al under experimental conditions that favor the dominance of region I (low-stress region) of the sigmoidal behavior characterizing high-strain-rate superplasticity, which was reported previously for the alloy.

Han, Jung H.; Mohamed, Farghalli A.



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



Quantitative analysis on collagen of dermatofibrosarcoma protuberans skin by second harmonic generation microscopy.  


Dermatofibrosarcoma protuberans (DFSP) is a skin cancer usually mistaken as other benign tumors. Abnormal DFSP resection results in tumor recurrence. Quantitative characterization of collagen alteration on the skin tumor is essential for developing a diagnostic technique. In this study, second harmonic generation (SHG) microscopy was performed to obtain images of the human DFSP skin and normal skin. Subsequently, structure and texture analysis methods were applied to determine the differences in skin texture characteristics between the two skin types, and the link between collagen alteration and tumor was established. Results suggest that combining SHG microscopy and texture analysis methods is a feasible and effective method to describe the characteristics of skin tumor like DFSP. SCANNING 9999:XX-XX, 2014. © 2014 Wiley Periodicals, Inc. PMID:25369371

Wu, Shulian; Huang, Yudian; Li, Hui; Wang, Yunxia; Zhang, Xiaoman



Noise coefficients of backscattered electron detectors for low voltage scanning electron microscopy.  


Noise coefficients of backscattered electron (BSE) detectors for low voltage scanning electron microscopy were studied theoretically and experimentally. The conversion method of BSE detection, the scintillation detector with an acceleration of BSE and detectors with electron multipliers were considered. Formulae for noise coefficients were derived and noise coefficients of detectors were computed for different values of gains of detectors' components. Theoretical predictions of noise coefficients were compared with experimental results. PMID:23879663

Hejna, J



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


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



Identification of bovine sperm head for morphometry analysis in quantitative phase-contrast holographic microscopy.  


An investigation is reported of the identification and measurement of region of interest (ROI) in quantitative phase-contrast maps of biological cells by digital holographic microscopy. In particular, two different methods have been developed for in vitro bull sperm head morphometry analysis. We show that semen analysis can be accomplished by means of the proposed techniques . Extraction and measurement of various parameters are performed. It is demonstrated that both proposed methods are efficient to skim the data set in a preselective analysis for discarding anomalous data. PMID:22109200

Memmolo, P; Di Caprio, G; Distante, C; Paturzo, M; Puglisi, R; Balduzzi, D; Galli, A; Coppola, G; Ferraro, P



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


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



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



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

NASA Astrophysics Data System (ADS)

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.

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



Combined Scanning Transmission Electron Microscopy Tilt- and Focal Series  

SciTech Connect

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

Dahmen, Tim [German Research Center for Artificial Intelligence (DFKI), Germany] [German Research Center for Artificial Intelligence (DFKI), Germany; Baudoin, Jean-Pierre G [ORNL] [ORNL; Lupini, Andrew R [ORNL] [ORNL; Kubel, Christian [Karlsruhe Institute of Technology, Leopoldshafen, Germany] [Karlsruhe Institute of Technology, Leopoldshafen, Germany; Slusallek, Phillip [German Research Center for Artificial Intelligence (DFKI), Germany] [German Research Center for Artificial Intelligence (DFKI), Germany; De Jonge, Niels [ORNL] [ORNL



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. PMID:23382239

Lorenz, Ulrich J.; Zewail, Ahmed H.



Accurate single-shot quantitative phase imaging of biological specimens with telecentric digital holographic microscopy.  


The advantages of using a telecentric imaging system in digital holographic microscopy (DHM) to study biological specimens are highlighted. To this end, the performances of nontelecentric DHM and telecentric DHM are evaluated from the quantitative phase imaging (QPI) point of view. The evaluated stability of the microscope allows single-shot QPI in DHM by using telecentric imaging systems. Quantitative phase maps of a section of the head of the drosophila melanogaster fly and of red blood cells are obtained via single-shot DHM with no numerical postprocessing. With these maps we show that the use of telecentric DHM provides larger field of view for a given magnification and permits more accurate QPI measurements with less number of computational operations. PMID:24781590

Doblas, Ana; Sánchez-Ortiga, Emilio; Martínez-Corral, Manuel; Saavedra, Genaro; Garcia-Sucerquia, Jorge



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. PMID:19941558




Magnetic vortex observation in FeCo nanowires by quantitative magnetic force microscopy  

NASA Astrophysics Data System (ADS)

An approach is presented that allows quantifying the three dimensional magnetization pattern of a magnetic nanoobject from measured two dimensional Magnetic Force Microscopy (MFM) data. This is based on a MFM deconvolution approach, which quantitatively determines the effective surface charges, on a micromagnetic calculation of the total magnetic charges at and below the sample surface, and on a projection of the lower lying charges onto the sample surface for a comparison of the such obtained effective surface charges with the experimentally determined ones. Thus, by making use of the depth sensitivity of MFM and by applying a quantitative contrast analysis, we are able to reconstruct the inhomogeneous magnetization state at the end of individual cylindrical Fe52Co48 nanowires arranged in a triangular array. As a result, we prove the existence of a magnetic vortex state at their ends.

Vock, S.; Hengst, C.; Wolf, M.; Tschulik, K.; Uhlemann, M.; Sasvári, Z.; Makarov, D.; Schmidt, O. G.; Schultz, L.; Neu, V.



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


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



A national facility for biological cryo-electron microscopy  

PubMed Central

Three-dimensional electron microscopy is an enormously powerful tool for structural biologists. It is now able to provide an understanding of the molecular machinery of cells, disease processes and the actions of pathogenic organisms from atomic detail through to the cellular context. However, cutting-edge research in this field requires very substantial resources for equipment, infrastructure and expertise. Here, a brief overview is provided of the plans for a UK national three-dimensional electron-microscopy facility for integrated structural biology to enable internationally leading research on the machinery of life. State-of-the-art equipment operated with expert support will be provided, optimized for both atomic-level single-particle analysis of purified macromolecules and complexes and for tomography of cell sections. The access to and organization of the facility will be modelled on the highly successful macromolecular crystallography (MX) synchrotron beamlines, and will be embedded at the Diamond Light Source, facilitating the development of user-friendly workflows providing near-real-time experimental feedback. PMID:25615867

Saibil, Helen R.; Grünewald, Kay; Stuart, David I.



Scanning electron microscopy of Anisakis larvae following different treatments.  


Ingestion of fish parasitized with Anisakis larvae can produce infestation and/or allergy in consumers. Technological and food processing treatments have been applied to parasitized fish in order to kill the larvae and avoid the infestation; however, their influence on allergenicity has not been studied. Four lots of hake (Merluccius merluccius) steaks artificially parasitized with Anisakis larvae were subjected to two storage chilling (5 degrees C +/- 1 degrees C) and freezing (-20 degrees C +/- 1 degrees C) treatments and two food processing treatments of heat (final temperature 86.3 degrees C) and microwave (final temperature 66.9 degrees C) and studied by scanning electron microscopy, environmental scanning electron microscopy (ESEM) (acid [pH = 2] and water preparations), and emission of fluorescence. Anisakis larvae were resistant to acid conditions, remaining alive after treatment. Larvae in the heat- and microwave-treated lots presented coagulated and disrupted zones in the cuticle with release of fluids. The cylindrical shape changed to a dehydrated appearance mainly observed by ESEM. Fluorescence was only noticeable in the frozen larvae. Larvae without apparent changes, together with dehydrated ones, were observed by ESEM in the frozen lot; nevertheless, no disruptions in the cuticle were perceptible. Further studies are needed in order to elucidate if the changes observed in the cuticle reduce the resistance of the parasites to the action of gastric enzymes in the gastrointestinal tract and to determine the release of allergens to the flesh by the live larvae during chilled storage of the fish. PMID:16786860

Tejada, Margarita; Solas, Maria Teresa; Navas, Alfonso; Mendizábal, Angel



Investigation of porous asphalt microstructure using optical and electron microscopy.  


Direct observations of porous asphalt concrete samples in their natural state using optical and electron microscopy techniques led to useful information regarding the microstructure of two mixes and indicated a relationship between microstructure and in situ performance. This paper presents evidence that suboptimal microstructure can lead to premature failure thus making a first step in defining well or suboptimal performing pavements with a bottom-up approach (microstructure). Laboratory and field compaction produce different samples in terms of the microstructure. Laboratory compaction using the gyratory method has produced more microcracks in mineral aggregates after the binder had cooled. Well-performing mixes used polymer-modified binders, had a more homogeneous void structure with fewer elongated voids and better interlocking of the aggregates. Furthermore, well-performing mixes showed better distribution of the mastic and better coverage of the aggregates with bitumen. Low vacuum scanning electron microscopy showed that styrene butadiene styrene polymer modification in binder exists in the form of discontinuous globules and not continuous networks. A reduction in the polymer phase was observed as a result of aging and in-service use. PMID:20946381

Poulikakos, L D; Partl, M N



Simulation Study Of Transmission Electron Microscopy Imaging Of Graphene Stacking  

NASA Astrophysics Data System (ADS)

Graphene is the subject of intense study due to its high mobility and mechanical integrity. These properties make it an attractive material for the "beyond CMOS" technology that will replace today's transistor. Acceleration of process and device technology requires considerable advances in the imaging and characterization of graphene. The physical dimensions of available single and multi-layer samples are not large enough for many metrology methods. For example, the spot size of ellipsometry is typically larger than available samples. Electron microscopy of graphene is also challenging. Carbon is a difficult element to image with electron microscopy because of its low atomic number. The high mobility of single layer and misoriented two and three layer graphene make it attractive for nanoelectronics. The current investigation explores HRTEM simulations of graphene stacking configurations AAA/ABA/ABC as well as bilayers with misorientations between the individual layers. HAADF (High Angle Annular Dark Field) STEM simulation is also discussed. Images calculated using the Multislice algorithm show discernable differences between the stacking sequences when simulated in the presence of random noise.

Nelson, F.; Diebold, A. C.; Hull, R.



Amyloid Structure and Assembly: Insights from Scanning Transmission Electron Microscopy  

SciTech Connect

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

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



A Technique for In Situ Ballistic Electron Emission Microscopy  

NASA Astrophysics Data System (ADS)

Ballistic electron emission microscopy (BEEM) is a scanning tunneling microscopy (STM) technique that can measure transport of hot electrons through materials and interfaces with high spatial and energetic resolution. BEEM requires an additional contact to ground the metal base layer of a metal semiconductor junction. Performing BEEM in situ with the sample fabrication requires a custom built STM or modifying a commercial one to facilitate the extra contact, which leaves the technique to highly trained experts. This poster will describe our work to develop a special silicon substrate that has the extra contact built in to enable in situ BEEM without modifications to the STM. Electrically isolated contact traces are lithographically patterned ex situ onto the silicon substrate and connected to the BEEM sample plate which is then inserted into the ultra-high vacuum chamber. The metal is then deposited through a shadow mask and then mounted in situ onto the STM for BEEM measurements. BEEM measurements comparing both in situ and ex situ deposited films will be presented.

Balsano, Robert; Garramone, John; Labella, Vincent



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


Atomic scale characterization of materials using scanning transmission electron microscopy  

NASA Astrophysics Data System (ADS)

Coupling the development of emerging experimental techniques in STEM and EELS with a fundamental understanding of atomic electronic structure afforded by DFT represents the unique approach and intention of this thesis. Scanning transmission electron microscopes equipped with high-angle annular dark field (HAADF) detectors and Gatan image filters (GIF) provide images and spectra, where the image brightness is interpreted as a function of atomic mass and thickness, and elemental specific spectra provide a means for the exploration of electronic and chemical structure of materials at the angstrom size scale. Over the past 20 years, the application of EELS in STEM has enabled more accurate elemental identification and exploration of electronic and chemical structure on angstrom-length scales, and arguably has provided an unprecedented wealth of materials characterization compared to other available techniques. Many materials issues related to specific novel properties that cannot be analyzed using the traditional techniques of the past, however, still remain unanswered. These concepts require a married approach of experiment and theory to fully explain. The intent of this dissertation is the development of improved analysis techniques that derive quantitative atomic scale information in connection with unraveling the origins of materials properties linked to the electronic structure and chemistry of materials.

Aguiar, Jeffery Andrew


The application of polyethylene glycol (PEG) to electron microscopy  

PubMed Central

The cytoplasm of cells from a variety of tissues has been viewed in sections (0.25-1 micrometers) devoid of any embedding resin. Glutaraldehyde- and osmium tetroxide-fixed tissues were infiltrated and embedded in a water-miscible wax, polyethylene glycol (PEG), and subsequently sectioned on dry glass or diamond knives. The PEG matrix was removed and the sections were placed on Formvarcarbon-polylysine- coated grids, dehydrated, dried by the critical-point method, and observed in either the high- or low-voltage electron microscope. Stereoscopic views of cells devoid of embedding resin present an image of cell utrastructure unobscured by electron-scattering resins similar to the image of whole, unembedded critical-point-dried or freeze-dried cultured cells observed by transmission electron microscopy. All organelles, including the cytoskeletal structures, are identified and appear not to have been damaged during processing, although membrane components appear somewhat less distinct. The absence of an embedding matrix eliminates the need for additional staining to increase contrast, unlike the situation with specimens embedded in standard electron-scattering resins. The PEG technique thus appears to be a valuable adjunct to conventional methods for ultrastructural analysis. PMID:7400222



Electron microscopy and atomic force microscopy studies of chromatin and metaphase chromosome structure.  


The folding of the chromatin filament and, in particular, the organization of genomic DNA within metaphase chromosomes has attracted the interest of many laboratories during the last five decades. This review discusses our current understanding of chromatin higher-order structure based on results obtained with transmission electron microscopy (TEM), cryo-electron microscopy (cryo-EM), and different atomic force microscopy (AFM) techniques. Chromatin isolated from different cell types in buffers without cations form extended filaments with nucleosomes visible as separated units. In presence of low concentrations of Mg(2+), chromatin filaments are folded into fibers having a diameter of ? 30 nm. Highly compact fibers were obtained with isolated chromatin fragments in solutions containing 1-2mM Mg(2+). The high density of these fibers suggested that the successive turns of the chromatin filament are interdigitated. Similar results were obtained with reconstituted nucleosome arrays under the same ionic conditions. This led to the proposal of compact interdigitated solenoid models having a helical pitch of 4-5 nm. These findings, together with the observation of columns of stacked nucleosomes in different liquid crystal phases formed by aggregation of nucleosome core particles at high concentration, and different experimental evidences obtained using other approaches, indicate that face-to-face interactions between nucleosomes are very important for the formation of dense chromatin structures. Chromatin fibers were observed in metaphase chromosome preparations in deionized water and in buffers containing EDTA, but chromosomes in presence of the Mg(2+) concentrations found in metaphase (5-22 mM) are very compact, without visible fibers. Moreover, a recent cryo-electron microscopy analysis of vitreous sections of mitotic cells indicated that chromatin has a disordered organization, which does not support the existence of 30-nm fibers in condensed chromosomes. TEM images of partially denatured chromosomes obtained using different procedures that maintain the ionic conditions of metaphase showed that bulk chromatin in chromosomes is organized forming multilayered plate-like structures. The structure and mechanical properties of these plates were studied using cryo-EM, electron tomography, AFM imaging in aqueous media, and AFM-based nanotribology and force spectroscopy. The results obtained indicated that the chromatin filament forms a flexible two-dimensional network, in which DNA is the main component responsible for the mechanical strength observed in friction force measurements. The discovery of this unexpected structure based on a planar geometry has opened completely new possibilities for the understanding of chromatin folding in metaphase chromosomes. It was proposed that chromatids are formed by many stacked thin chromatin plates oriented perpendicular to the chromatid axis. Different experimental evidences indicated that nucleosomes in the plates are irregularly oriented, and that the successive layers are interdigitated (the apparent layer thickness is 5-6 nm), allowing face-to-face interactions between nucleosomes of adjacent layers. The high density of this structure is in agreement with the high concentration of DNA observed in metaphase chromosomes of different species, and the irregular orientation of nucleosomes within the plates make these results compatible with those obtained with mitotic cell cryo-sections. The multilaminar chromatin structure proposed for chromosomes allows an easy explanation of chromosome banding and of the band splitting observed in stretched chromosomes. PMID:21703860

Daban, Joan-Ramon



LAUR-82-1433 Wohletz and Krinsley: Scanning Electron Microscopy... 1  

E-print Network

Abstract The scanning electron microscope was used to study the surface textures of basaltic hydromagmatic#12;LAUR-82-1433 Wohletz and Krinsley: Scanning Electron Microscopy... 1 Scanning Electron. Introduction Scanning electron microscopy (SEM) plays an increasing role in geology as a tool for understanding


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



Quantitative Electron Tomography of Rubber Composites  

NASA Astrophysics Data System (ADS)

Rubber composite materials have many applications, one example being tyre manufacture. The presence of a filler material in the composite (such as carbon black or silica) causes its mechanical properties to differ in several ways when compared to pure rubber such as viscoelastic behaviour (the Payne effect), increased tensile strength and improved wear resistance. To fully understand these properties, it is necessary to characterise how the filler material is organised on the nanoscale. Using composite materials representative of those found in tyres, this work illustrates the use of electron tomography and machine learning methods as tools to describe the percolation behaviour of the filler; in this case, we focus on the largest proportion of particles absorbed into one single object as a function of particle spacing.

Staniewicz, Lech; Vaudey, Thomas; Degrandcourt, Christophe; Couty, Marc; Gaboriaud, Fabien; Midgley, Paul



Scanning electrochemical microscopy at thermal sprayed anti-corrosion coatings: Effect of thermal spraying on heterogeneous electron transfer kinetics  

Microsoft Academic Search

The effect of thermal spraying on the electrochemical activity of an anti-corrosion superalloy was studied quantitatively using scanning electrochemical microscopy (SECM). The superalloy used was Inconel 625 (a Ni base superalloy) and thin coatings of the alloy were formed on mild steel using high velocity oxy-fuel (HVOF) thermal spraying. The kinetics of electron transfer (ET) across the Inconel 625 coating\\/electrolyte

Lee Johnson; Akbar Niaz; Adrian Boatwright; K. T. Voisey; Darren A. Walsh



Atmospheric Environment 42 (2008) 19831994 Using environmental scanning electron microscopy to determine  

E-print Network

samples using a cascade impactor system and have used an environmental scanning electron microscope (ESEM: Agricultural aerosol; Visibility; Hygroscopicity; Environmental scanning electron microscope (ESEM); EnergyAtmospheric Environment 42 (2008) 1983­1994 Using environmental scanning electron microscopy


Identification and quantitive analysis of calcium phosphate microparticles in intestinal tissue by nuclear microscopy  

NASA Astrophysics Data System (ADS)

Microscopic particles (0.5-2 ?m diameter), rich in calcium and phosphorus, are found in the lumen of the mid-distal gut of all mammals investigated, including humans, and these may play a role in immuno-surveillance and immune regulation of antigens from food and symbiotic bacteria that are contained in the gut. Whether these particles can cross in to tissue of the intestinal mucosa is unclear. If so, characterising their morphology and chemical composition is an important task in elucidating their function. The analysis of calcium phosphate in biological tissues has been approached in several ways including optical microscopy, scanning electron microscopy and, most recently in this work, with nuclear microscopy. In this paper, we describe the use of microPIXE and microRBS to locate these particles and to determine, accurately, the ratio of phosphorus to calcium using the information on sample thickness obtained from RBS to allow the PIXE ratios to be corrected. A commercial sample of hydroxy apatite was used to demonstrate accuracy and precision of the technique. Then, in a pilot study on intestinal tissue of mice, we demonstrated the presence of calcium phosphate microparticles, consistent with confocal microscopy observations, and we identified the average molar P:Ca molar ratio as 1.0. Further work will confirm the exact chemical speciation of these particles and will examine the influence of differing calcium containing diets on the formation of these microparticles.

Gomez-Morilla, Inmaculada; Thoree, Vinay; Powell, Jonathan J.; Kirkby, Karen J.; Grime, Geoffrey W.



Electron microscopy in rapid viral diagnosis: an update.  


Diagnostic electron microscopy (DEM) has conceptual predecessors â€" the application of the sense of vision and of light microscopy in medicine. The evolvement of DEM and the role of its two branches - histopathology and rapid negative-contrast DEM - are described in this review, with a focus on the latter. By its resolving power of 2 nm in praxi, DEM is able to visualize all kinds of pathogens, bacteria, parasites, even the smallest viruses. In contrast to other laboratory diagnostic methods, DEM excels by speed and "open view". All structures on the support grid can be assigned directly by "pattern recognition" of their fine structure to a specific family of agents. The morphology-based "catch-all" diagnosis can be decisive as a differential diagnosis and will help as a preliminary diagnosis to select and apply proper diagnostic tools for typing of the observed agent. Based on two case reports, the advantages and possible pitfalls of DEM are exemplified and hints are given to make DEM reliable and effective. Finally the role of DEM in medicine and the wider fields of life sciences are described together with the organizational conditions to guarantee its future in laboratory diagnostics. PMID:25387280

Gentile, Massimo; Gerdelblom, Hans R



Contribution of scanning electron microscopy to viewing internal cell structure.  


Freeze-fracture provides a way of opening up cells and tissues for an internal view of cytoplasm and nucleus, and can give an internal view of a cytoplasmic organelle if the plane of fracture cuts through the organelle. Selective removal of soluble or other components is necessary for a deep view of structure at the fracture face. This may be achieved by osmium digestion, or by glycerol extraction, or by delaying fixation until after freeze-fracture and thawing, or by prior treatment with detergent to remove cell membranes and wash out soluble components. Cells may also be ruptured at room temperature, or in certain cases prepared to expose the inner surface of the plasma membrane for scanning electron microscopy (SEM) viewing. The problems and potential of SEM viewing of the cell interior are in certain respects similar to those encountered and derived from TEM replica study of freeze-fractured cells after deep etching. TEM replicas give better resolution, while SEM offers advantages in study of surfaces with considerable depth of structure. Study of fresh material, without fixation or alcohol dehydration, by rapid freezing and deep etching, is increasing our understanding of the artifacts that can be produced by these two preparative steps which are essential to critical point drying, whether used as a preparative step for SEM or for whole-mount high-voltage TEM microscopy. PMID:6762649

Haggis, G H



Nanoscale mechanical drumming visualized by 4D electron microscopy.  


With four-dimensional (4D) electron microscopy, we report in situ imaging of the mechanical drumming of a nanoscale material. The single crystal graphite film is found to exhibit global resonance motion that is fully reversible and follows the same evolution after each initiating stress pulse. At early times, the motion appears "chaotic" showing the different mechanical modes present over the micron scale. At longer time, the motion of the thin film collapses into a well-defined fundamental frequency of 1.08 MHz, a behavior reminiscent of mode locking; the mechanical motion damps out after approximately 200 micros and the oscillation has a "cavity" quality factor of 150. The resonance time is determined by the stiffness of the material, and for the 75 nm thick and 40 microm square specimen used here we determined Young's modulus to be 1.0 TPa for the in-plane stress-strain profile. Because of its real-time dimension, this 4D microscopy should have applications in the study of these and other types of materials structures. PMID:19006405

Kwon, Oh-Hoon; Barwick, Brett; Park, Hyun Soon; Baskin, J Spencer; Zewail, Ahmed H




PubMed Central

The ultrastructure of the uterine epithelium has been studied in estrous, ovariectomized, pregnant, and pseudopregnant rabbits. Tissue for light microscopy was fixed in Bouin's solution and stained with hematoxylin and eosin, by the periodic acid-Schiff (PAS) method, and with methylene blue. Tissue for electron microscopy was fixed in 1 per cent osmium tetroxide in White's saline and embedded in Araldite. The uterine epithelium in estrus is comprised of ciliated and non-ciliated cells. After ovariectomy the epithelium becomes reduced in height and PAS-positive material disappears. Multinucleated cells are formed in the epithelium in pregnancy, pseudopregnancy, and in the non-pregnant horn in unilateral pregnancy. They degenerate during the 3rd week of pseudopregnancy and during the 4th week of pregnancy in the non-pregnant horn. The formation of multinucleated cells is believed to be under hormonal control. The uterine epithelium in contact with the blastocyst changes into a "symplasma," presumably under the influence of a local (chemical?) effect produced by the blastocyst. This change is not seen in pseudopregnancy nor in the non-pregnant horn in unilateral pregnancy. A complex infolding of the basal cell membrane of the epithelium accompanies the "symplasmic" change. The remaining uterine epithelium in pregnancy shows a well developed ergastoplasm suggesting a production of secretion materials, some of which may be available for absorption by the fetus through the yolk sac or paraplacental chorion. PMID:14462496

Larsen, Jørgen Falck



Using quantitative fluorescence microscopy and FRET imaging to measure spatiotemporal signaling events in single living cells.  


The mechanisms that mediate how migratory eukaryotic cells amplify a shallow, extracellular chemoattractant gradient into a steep intracellular gradient of signaling components to guide chemotaxis remains unknown. To unravel these mechanisms, it is essential to quantitatively measure the spatiotemporal patterns of chemoattractant gradients, the dynamic movement of intracellular signaling pathway molecules, and the localized activation of these molecules in single living cells. Recent developments in live-cell fluorescence microscopy have permitted direct visualization and quantitative measurement of signal transduction events with high temporal and spatial resolution. Here, we outline fluorescence imaging methods to simultaneously visualize and quantitatively measure spatiotemporal changes in chemoattractant concentration by using the fluorescent tracer dye Alexa 594. Next, we provide a method to correlate the dynamic changes in ligand to the spatiotemporal changes in the second messenger phosphatidylinositol 3,4,5-triphosphate (PIP3) along the inner surface of the plasma membrane in live cells. Finally, we describe a fluorescence resonance energy transfer (FRET) method to determine the extent of heterotrimeric G protein activation in single living cells in response to various chemoattractant fields. PMID:16957297

Xu, Xuehua; Brzostowski, Joseph A; Jin, Tian



Enhanced visualization of microbial biofilms by staining and environmental scanning electron microscopy.  


Bacterial biofilms, i.e. surface-associated cells covered in hydrated extracellular polymeric substances (EPS), are often studied with high-resolution electron microscopy (EM). However, conventional desiccation and high vacuum EM protocols collapse EPS matrices which, in turn, deform biofilm appearances. Alternatively, wet-mode environmental scanning electron microscopy (ESEM) is performed under a moderate vacuum and without biofilm drying. If completely untreated, however, EPS is not electron dense and thus is not resolved well in ESEM. Therefore, this study was towards adapting several conventional SEM staining protocols for improved resolution of biofilms and EPS using ESEM. Three different biofilm types were used: 1) Pseudomonas aeruginosa unsaturated biofilms cultured on membranes, 2) P. aeruginosa cultured in moist sand, and 3) mixed community biofilms cultured on substrates in an estuary. Working with the first specimen type, a staining protocol using ruthenium red, glutaraldehyde, osmium tetroxide and lysine was optimized for best topographic resolution. A quantitative image analysis tool that maps relief, newly adopted here for studying biofilms, was used to compare micrographs. When the optimized staining and ESEM protocols were applied to moist sand cultures and aquatic biofilms, the smoothening effect that bacterial biofilms have on rough sand, and the roughening that aquatic biofilms impart on initially smooth coupons, were each quantifiable. This study thus provides transferable staining and ESEM imaging protocols suitable for a wide range of biofilms, plus a novel tool for quantifying biofilm image data. PMID:17196692

Priester, John H; Horst, Allison M; Van de Werfhorst, Laurie C; Saleta, José L; Mertes, Leal A K; Holden, Patricia A



Microstructure analysis technique for aluminum metallzations by transmission electron microscopy  

NASA Astrophysics Data System (ADS)

This paper discusses two kinds of specimen preparation technique to observe the specific regions of aluminum lines and vias by transmission electron microscopy (TEM). The first technique is a plan-view specimen preparing method to observe the voids in aluminum lines. The procedure consists of a polymerized film coating, mechanical polishing, ion milling and dry etching. Aluminum lines supported with polymerized film remain in the specimen prepared by this technique. The second technique is a cross-sectional specimen preparing method to observe specific regions. The procedure consists of mechanical polishing and focused ion beam (FIB) etching. A very thin sliver containing the specific region is left by FIB etching. These sample preparation techniques allow analysis of stress-induced voids at aluminum lines and aluminum/aluminum vias.

Hata, Y.; Nanatsue, H.; Hidaka, Y.; Harada, Y.; Inoue, M.



A simple and inexpensive route to remote electron microscopy  

SciTech Connect

Due to the availability of fast computer networks such as Ethernet, FDDI and ATM, the idea of Telemicroscopy, including running electron microscopes from remote locations has gained momentum. Fan, Ellisman, Zaluzec and Parvin, have discussed aspects of systems which support such capabilities. In each of these reports the authors describe new stand-alone software packages that are required to run their systems. In order to make remote microscopy more universally available, we have chosen to expand de facto standard commercial software to provide for computerized microscope control and remote control. In order to access one of our instrument at Oak Ridge National Laboratory from your own office or lab, simply send a request via email to: ``. We will then be able to contact you and set up a time so you can run these microscopes from your site.

Voelkl, E.; Allard, L.F.; Nolan, T.A. [Oak Ridge National Lab., TN (United States)] [and others



High Resolution Scanning Electron Microscopy of Cells Using Dielectrophoresis  

PubMed Central

Ultrastructural analysis of cells can reveal valuable information about their morphological, physiological, and biochemical characteristics. Scanning electron microscopy (SEM) has been widely used to provide high-resolution images from the surface of biological samples. However, samples need to be dehydrated and coated with conductive materials for SEM imaging. Besides, immobilizing non-adherent cells during processing and analysis is challenging and requires complex fixation protocols. In this work, we developed a novel dielectrophoresis based microfluidic platform for interfacing non-adherent cells with high-resolution SEM at low vacuum mode. The system enables rapid immobilization and dehydration of samples without deposition of chemical residues over the cell surface. Moreover, it enables the on-chip chemical stimulation and fixation of immobilized cells with minimum dislodgement. These advantages were demonstrated for comparing the morphological changes of non-budding and budding yeast cells following Lyticase treatment. PMID:25089528

Tang, Shi-Yang; Zhang, Wei; Soffe, Rebecca; Nahavandi, Sofia; Shukla, Ravi; Khoshmanesh, Khashayar



New Approach to Image Aerogels by Scanning Electron Microscopy  

NASA Astrophysics Data System (ADS)

A new scanning electron microscopy (SEM) technique to image poor electrically conductive aerogels is presented. The process can be performed by non-expert SEM users. We showed that negative charging effects on aerogels can be minimized significantly by inserting dry nitrogen gas close to the region of interest. The process involves the local recombination of accumulated negative charges with positive ions generated from ionization processes. This new technique made possible the acquisition of images of aerogels with pores down to approximately 3nm in diameter using a positively biased Everhart-Thornley (E-T) detector. Well-founded concepts based on known models will also be presented with the aim to explain the results qualitatively.

Solá, Francisco; Hurwitz, Frances; Yang, Jijing



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. PMID:3755397

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



Fluctuation electron microscopy studies of complex structured materials  

NASA Astrophysics Data System (ADS)

Fluctuation electron microscopy (FEM) is a hybrid imaging-diffraction technique. This technique is particularly sensitive to paracrystalline structures of dimension 0.5-2 nm, which are difficult to detect by either imaging or diffraction techniques alone. It has been successfully deployed to study paracrystalline structures in amorphous silicon, germanium thin film. This technique has also been used to study metallic glasses and oxide glasses. Until now, FEM has not been used to study disordered geological materials. In this talk we present our FEM studies of shungite, a naturally occurring disordered carbonaceous material, reveal that trace quantities of tightly curved graphene structures such as C60, or fragments of C60, is present in shungite. We also present results from our study of metamict zircon, whose crystal structure is destroyed by self-radiation during naturally occurring ? decay events. Work is in progress to study the structural evolution during the metamictization process.

Zhao, Gongpu; Rougée, Annick; Buseck, Peter; Treacy, Michael



Morphological classification of bioaerosols from composting using scanning electron microscopy.  


This research classifies the physical morphology (form and structure) of bioaerosols emitted from open windrow composting. Aggregation state, shape and size of the particles captured are reported alongside the implications for bioaerosol dispersal after release. Bioaerosol sampling took place at a composting facility using personal air filter samplers. Samples were analysed using scanning electron microscopy. Particles were released mainly as small (<1 ?m) single, spherical cells, followed by larger (>1 ?m) single cells, with aggregates occurring in smaller proportions. Most aggregates consisted of clusters of 2-3 particles as opposed to chains, and were <10 ?m in size. No cells were attached to soil debris or wood particles. These small single cells or small aggregates are more likely to disperse further downwind from source, and cell viability may be reduced due to increased exposure to environmental factors. PMID:24565805

Tamer Vestlund, A; Al-Ashaab, R; Tyrrel, S F; Longhurst, P J; Pollard, S J T; Drew, G H



Watershed Merge Tree Classification for Electron Microscopy Image Segmentation  

SciTech Connect

Automated segmentation of electron microscopy (EM) images is a challenging problem. In this paper, we present a novel method that utilizes a hierarchical structure and boundary classification for 2D neuron segmentation. With a membrane detection probability map, a watershed merge tree is built for the representation of hierarchical region merging from the watershed algorithm. A boundary classifier is learned with non-local image features to predict each potential merge in the tree, upon which merge decisions are made with consistency constraints in the sense of optimization to acquire the final segmentation. Independent of classifiers and decision strategies, our approach proposes a general framework for efficient hierarchical segmentation with statistical learning. We demonstrate that our method leads to a substantial improvement in segmentation accuracy.

Liu, TIng; Jurrus, Elizabeth R.; Seyedhosseini, Mojtaba; Ellisman, Mark; Tasdizen, Tolga



Collaborative Computational Project for Electron cryo-Microscopy  

PubMed Central

The Collaborative Computational Project for Electron cryo-Microscopy (CCP-EM) has recently been established. The aims of the project are threefold: to build a coherent cryoEM community which will provide support for individual scientists and will act as a focal point for liaising with other communities, to support practising scientists in their use of cryoEM software and finally to support software developers in producing and disseminating robust and user-friendly programs. The project is closely modelled on CCP4 for macromolecular crystallo­graphy, and areas of common interest such as model fitting, underlying software libraries and tools for building program packages are being exploited. Nevertheless, cryoEM includes a number of techniques covering a large range of resolutions and a distinct project is required. In this article, progress so far is reported and future plans are discussed. PMID:25615866

Wood, Chris; Burnley, Tom; Patwardhan, Ardan; Scheres, Sjors; Topf, Maya; Roseman, Alan; Winn, Martyn



Logic upsets in SRAMs using ion electron emission microscopy  

NASA Astrophysics Data System (ADS)

A high linear energy transfer (LET) system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratories in Albuquerque. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff - Pelletron from 0.25 to 1.9 MeV/amu. The LET for heavy ions is near a maximum at this velocity and the range is ˜20 ?m. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor, which makes focusing such ions difficult. To circumvent this problem, we are not using a focused microbeam, but instead are employing an ion-electron emission microscope or IEEM to perform high-LET REM experiments. Details of the RFQ-Booster and the new Axial IEEM system are given. Results using IEEM-IBIC to observe single event upsets in Sandia-manufactured radiation hardened integrated circuits are also presented and interpreted.

Doyle, B. L.; McDaniel, F. D.; Vizkelethy, G.; Dodd, P. E.; Rossi, P.; Walsh, D. S.



Correlating Intravital Multi-Photon Microscopy to 3D Electron Microscopy of Invading Tumor Cells Using Anatomical Reference Points  

PubMed Central

Correlative microscopy combines the advantages of both light and electron microscopy to enable imaging of rare and transient events at high resolution. Performing correlative microscopy in complex and bulky samples such as an entire living organism is a time-consuming and error-prone task. Here, we investigate correlative methods that rely on the use of artificial and endogenous structural features of the sample as reference points for correlating intravital fluorescence microscopy and electron microscopy. To investigate tumor cell behavior in vivo with ultrastructural accuracy, a reliable approach is needed to retrieve single tumor cells imaged deep within the tissue. For this purpose, fluorescently labeled tumor cells were subcutaneously injected into a mouse ear and imaged using two-photon-excitation microscopy. Using near-infrared branding, the position of the imaged area within the sample was labeled at the skin level, allowing for its precise recollection. Following sample preparation for electron microscopy, concerted usage of the artificial branding and anatomical landmarks enables targeting and approaching the cells of interest while serial sectioning through the specimen. We describe here three procedures showing how three-dimensional (3D) mapping of structural features in the tissue can be exploited to accurately correlate between the two imaging modalities, without having to rely on the use of artificially introduced markers of the region of interest. The methods employed here facilitate the link between intravital and nanoscale imaging of invasive tumor cells, enabling correlating function to structure in the study of tumor invasion and metastasis. PMID:25479106

Karreman, Matthia A.; Mercier, Luc; Schieber, Nicole L.; Shibue, Tsukasa; Schwab, Yannick; Goetz, Jacky G.



Correlating Intravital Multi-Photon Microscopy to 3D Electron Microscopy of Invading Tumor Cells Using Anatomical Reference Points.  


Correlative microscopy combines the advantages of both light and electron microscopy to enable imaging of rare and transient events at high resolution. Performing correlative microscopy in complex and bulky samples such as an entire living organism is a time-consuming and error-prone task. Here, we investigate correlative methods that rely on the use of artificial and endogenous structural features of the sample as reference points for correlating intravital fluorescence microscopy and electron microscopy. To investigate tumor cell behavior in vivo with ultrastructural accuracy, a reliable approach is needed to retrieve single tumor cells imaged deep within the tissue. For this purpose, fluorescently labeled tumor cells were subcutaneously injected into a mouse ear and imaged using two-photon-excitation microscopy. Using near-infrared branding, the position of the imaged area within the sample was labeled at the skin level, allowing for its precise recollection. Following sample preparation for electron microscopy, concerted usage of the artificial branding and anatomical landmarks enables targeting and approaching the cells of interest while serial sectioning through the specimen. We describe here three procedures showing how three-dimensional (3D) mapping of structural features in the tissue can be exploited to accurately correlate between the two imaging modalities, without having to rely on the use of artificially introduced markers of the region of interest. The methods employed here facilitate the link between intravital and nanoscale imaging of invasive tumor cells, enabling correlating function to structure in the study of tumor invasion and metastasis. PMID:25479106

Karreman, Matthia A; Mercier, Luc; Schieber, Nicole L; Shibue, Tsukasa; Schwab, Yannick; Goetz, Jacky G



Electronic environment for a field emission gun in electron microscopy H. Pinna, K. Liang (*), M. Denizart and B. Jouffrey  

E-print Network

659 Electronic environment for a field emission gun in electron microscopy H. Pinna, K. Liang of the source given by a field emis- sion gun is particularly interesting in electron microscopy. This paper ofthe numerous disruptive breakdowns which can occur in that type of gun. The fluctuations

Paris-Sud XI, Université de


Superhydrophobic and adhesive properties of surfaces: testing the quality by an elaborated scanning electron microscopy method.  


In contrast to advancements in the fabrication of new superhydrophobic materials, the characterization of their water repellency and quality is often coarse and unsatisfactory. In view of the problems and inaccuracies, particularly in the measurement of very high contact angles, we developed alternative methods for the characterization of superhydrophobic surfaces. It was found that adhering water remnants after immersion are a useful criterion in determining the repellency quality. In this study, we introduce microscopy methods to detect traces of water-resembling test liquids on superhydrophobic surfaces by scanning electron microscopy (SEM) or fluorescence light microscopy (FLM). Diverse plant surfaces and some artificial superhydrophobic samples were examined. Instead of pure water, we used aqueous solutions containing a detectable stain and glycerol in order to prevent immediate evaporation of the microdroplets. For the SEM examinations, aqueous solutions of lead acetate were used, which could be detected in a frozen state at -90 °C with high sensitivity using a backscattered electron detector. For fluorescence microscopy, aqueous solutions of auramine were used. On different species of superhydrophobic plants, varying patterns of remaining microdroplets were found on their leaves. On some species, drop remnants occurred only on surface defects such as damaged epicuticular waxes. On others, microdroplets regularly decorated the locations of increased adhesion, particularly on hierarchically structured surfaces. Furthermore, it is demonstrated that the method is suitable for testing the limits of repellency under harsh conditions, such as drop impact or long-enduring contact. The supplementation of the visualization method by the measurement of the pull-off force between a water drop and the sample allowed us to determine the adhesive properties of superhydrophobic surfaces quantitatively. The results were in good agreement with former studies of the water repellency and contact angles. In contrast to contact angle measurements, the acqusition of SEM images with high resolution and wide depth of sharpness gives better insight into the wetting behavior and susceptibility of the structural elements of the superhydrophobic surfaces. PMID:22978578

Ensikat, Hans J; Mayser, Matthias; Barthlott, Wilhelm



Quantitative Auger electron spectroscopy of SiC  

Microsoft Academic Search

The article is devoted to quantitative Auger electron spectroscopy (AES) of silicon carbide (SiC). It compares the results obtained by various procedures applied to LVV and KLL Auger peaks of silicon (Si) for determining the Auger current. We have found that reliable results for the content of Si in SiC can be achieved by the method in which the Auger

R. Kosiba; J. Liday; G. Ecke; O. Ambacher; J. Breza; P. Vogrin?i?



Quantitative Auger electron analysis of gold--copper alloys  

Microsoft Academic Search

Quantitative Auger electron analysis was established for gold (7 to 80 atomic percent)--copper alloys. The procedure for preparing samples must include uniform metallographic polishing and final sputter etching before Auger analysis. A 30-second sputter etch in argon is required to minimize the effects of surface contaminants. Beam current and potential were systematically varied to determine their effects on the resulting

R. L. Hanlin; D. L. Stoltz



Capturing enveloped viruses on affinity grids for downstream cryo-electron microscopy applications  

Technology Transfer Automated Retrieval System (TEKTRAN)

Electron microscopy cryo-electron microscopy and cryo-electron tomography are essential techniques used for characterizing basic virus morphology and determining the three-dimensional structure of viruses. Enveloped viruses, which contain an outer lipoprotein coat, constitute the largest group of pa...


Combined scanning transmission electron microscopy tilt- and focal series.  


In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt-focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller "missing wedge" artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography. PMID:24548618

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



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.



High Resolution Transmission Electron Microscopy (HRTEM) of nanophase ferric oxides  

NASA Technical Reports Server (NTRS)

Iron oxide minerals are the prime candidates for Fe(III) signatures in remotely sensed Martian surface spectra. Magnetic, Mossbauer, and reflectance spectroscopy have been carried out in the laboratory in order to understand the mineralogical nature of Martian analog ferric oxide minerals of submicron or nanometer size range. Out of the iron oxide minerals studied, nanometer sized ferric oxides are promising candidates for possible Martian spectral analogs. 'Nanophase ferric oxide (np-Ox)' is a generic term for ferric oxide/oxihydroxide particles having nanoscale (less than 10 nm) particle dimensions. Ferrihydrite, superparamagnetic particles of hematite, maghemite and goethite, and nanometer sized particles of inherently paramagnetic lepidocrocite are all examples of nanophase ferric oxides. np-Ox particles in general do not give X-ray diffraction (XRD) patterns with well defined peaks and would often be classified as X-ray amorphous. Therefore, different np-Oxs preparations should be characterized using a more sensitive technique e.g., high resolution transmission electron microscopy (HRTEM). The purpose of this study is to report the particle size, morphology and crystalline order, of five np-Ox samples by HRTEM imaging and electron diffraction (ED).

Golden, D. C.; Morris, R. V.; Ming, D. W.; Lauer, H. V., Jr.



Advanced scanning transmission electron microscopy characterization of UV LED nanowires  

NASA Astrophysics Data System (ADS)

The role of aberration-corrected scanning transmission electron microscopy (STEM) in materials characterization is examined in regards to Al(x)Ga(1-x)N nanowires. Wires were graded from x=0 to x=1 and then from x=1 to x=0 with a small active quantum disk region located between the two gradations. This configuration is the basis for previously reported UV light emitting diodes. However, to assist subsequent growth processes while striving for optimum efficiency, both structural and chemical characterization methods are necessary, which can be provided at sufficiently high resolutions by advanced STEM instruments. Specifically, structural characterization will focus on determining layer thicknesses and wire polarity, as well as visualizing any short-range ordering and/or stacking faults that may be present. STEM multislice image simulations will also be discussed. Chemically, both energy dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies will be discussed in various capacities, ranging from quantum well composition (EDX) to N K-edge fine structure of both GaN and AlN (EELS).

Phillips, Patrick; Kumar, Rajan; Carnevale, Santino; Myers, Roberto; Klie, Robert



Bsoft: image and molecular processing in electron microscopy.  


Software for the processing of electron micrographs in structural biology suffers from incompatibility between different packages, poor definition and choice of conventions, and a lack of coherence in software development. The solution lies in adopting a common philosophy of interaction and conventions between the packages. To understand the choices required to have such common interfaces, I am developing a package called "Bsoft." Its foundations lie in the variety of different image file formats used in electron microscopy-a continually frustrating experience to the user and programmer alike. In Bsoft, this problem is greatly diminished by support for many different formats (including MRC, SPIDER, IMAGIC, SUPRIM, and PIF) and by separating algorithmic issues from image format-specific issues. In addition, I implemented a generalized functionality for reading the tag-base STAR (self-defining text archiving and retrieval) parameter file format as a mechanism to exchanging parameters between different packages. Bsoft is written in highly portable code (tested on several Unix systems and under VMS) and offers a continually growing range of image processing functionality, such as Fourier transformation, cross-correlation, and interpolation. Finally, prerequisites for software collaboration are explored, which include agreements on information exchange and conventions, and tests to evaluate compatibility between packages. PMID:11472087

Heymann, J B



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.



Ultra-high vacuum scanning thermal microscopy for nanometer resolution quantitative thermometry.  


Understanding energy dissipation at the nanoscale requires the ability to probe temperature fields with nanometer resolution. Here, we describe an ultra-high vacuum (UHV)-based scanning thermal microscope (SThM) technique that is capable of quantitatively mapping temperature fields with ?15 mK temperature resolution and ?10 nm spatial resolution. In this technique, a custom fabricated atomic force microscope (AFM) cantilever, with a nanoscale Au-Cr thermocouple integrated into the tip of the probe, is used to measure temperature fields of surfaces. Operation in an UHV environment eliminates parasitic heat transport between the tip and the sample enabling quantitative measurement of temperature fields on metal and dielectric surfaces with nanoscale resolution. We demonstrate the capabilities of this technique by directly imaging thermal fields in the vicinity of a 200 nm wide, self-heated, Pt line. Our measurements are in excellent agreement with computational results-unambiguously demonstrating the quantitative capabilities of the technique. UHV-SThM techniques will play an important role in the study of energy dissipation in nanometer-sized electronic and photonic devices and the study of phonon and electron transport at the nanoscale. PMID:22530657

Kim, Kyeongtae; Jeong, Wonho; Lee, Woochul; Reddy, Pramod



Using advanced electron microscopy for the characterization of catalytic materials  

NASA Astrophysics Data System (ADS)

Catalysis will continue to be vitally important to the advancement and sustainability of industrialized societies. Unfortunately, the petroleum-based resources that currently fuel the energy and consumer product needs of an advancing society are becoming increasingly difficult and expensive to extract as supplies diminish and the quality of sources degrade. Therefore, the development of sustainable energy sources and the improvement of the carbon efficiency of existing chemical processes are critical. Further challenges require that these initiatives are accomplished in an environmentally friendly fashion since the effects of carbon-based emissions are proving to be a serious threat to global climate stability. In this dissertation, materials being developed for sustainable energy and process improvement initiatives are studied. Our approach is to use materials characterization, namely advanced electron microscopy, to analyze the targeted systems at the nano- or Angstrom-scale with the goal of developing useful relationships between structure, composition, crystalline order, morphology, and catalytic performance. One area of interest is the complex Mo-V-M-O (M=Te, Sb, Ta, Nb) oxide system currently being developed for the selective oxidation/ammoxidation of propane to acrylic acid or acrylonitrile, respectively. Currently, the production of acrylic acid and acrylonitrile rely on propylene-based processes, yet significant cost savings could be realized if the olefin-based feeds could be replaced by paraffin-based ones. The major challenge preventing this feedstock replacement is the development of a suitable paraffin-activating catalyst. Currently, the best candidate is the Mo-V-Nb-Te-O complex oxide catalyst that is composed of two majority phases that are commonly referred to as M1 and M2. However, there is a limited understanding of the roles of each component with respect to how they contribute to catalyst stability and the reaction mechanism. Aberration-corrected electron microscopy was used to systematically examine, atomic column by atomic column, the effect of elemental substitution on the long-range crystalline order, atomic coordinates, and site occupancies of the various formulations such that trends could be developed linking these properties to catalytic yields. To accomplish this task, an algorithm was developed that enabled the direct extraction of atomic coordinates and site occupancies from high-angle annular dark-field (HAADF) images to within 1% and 15% uncertainty, respectively. Furthermore, this general method could be applied to various crystalline systems and may dramatically improve the quality of initial structural models used in Rietveld refinements. Improvement in the quality of starting models may increase the structural and chemical complexity of inorganic structures that can be solved by using "powder methods" alone. In addition to the development of these trends, HAADF analyses also revealed the presence of coherent compositional miscibility gaps, rotational twin domains, and structural intergrowths in the complex Mo-V-M-O oxide system. Other catalytic systems that are addressed in this dissertation include Pd, Ag, and bimetallic Pd-Ag catalysts for the selective hydrogenation of acetylene in excess ethylene, alkali and alkaline earth promoted Ru catalysts for the production of clean hydrogen through the decomposition of ammonia, the production of Pt nanoparticles using dendrimer templates, and Pt-Re bimetallic catalysts for the conversion of glycerol to hydrocarbons and syn gas. In each of these studies, electron microscopy was used as a complimentary tool to synthetic and reaction studies to better understand interactions between the nanoparticles and the support/template, to determine the effect of adding various promoters, or to understand the nanoscale structural and chemical changes associated with the formation of bimetallic nanoparticles. A final area addressed in this dissertation is the interaction between the electron beam and the specimen. In one particular study direct

Pyrz, William D.


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



Hydrated human corneal stroma revealed by quantitative dynamic atomic force microscopy at nanoscale.  


The structures and mechanical properties of human tissues are significantly influenced by water. The functionality of the human cornea can be linked to the hydrated collagen fibers. By applying quantitative dynamic atomic force microscopy to investigate morphological and mechanical property variations of corneal stroma under different hydration levels, we found that the collagen fibers in the stromal tissue show the specific periodicities and the stiffness of giga-Pa magnitude at 40% humidity. However, under increasing hydration, the collagen fibers clearly show nanoparticle structures along the fibers with the stiffness in mega-Pa magnitude. By increasing the hydration time, the stroma regains the fiber structure but with larger diameter. The age-dependency in stiffness was further investigated. The interplay of structures and nanomechanical mapping may be applied for the future diagnosis and assessment or even pathologic analysis. PMID:24833346

Xia, Dan; Zhang, Shuai; Hjortdal, Jesper Østergaard; Li, Qiang; Thomsen, Karen; Chevallier, Jacques; Besenbacher, Flemming; Dong, Mingdong



Quantitative magnetic force microscopy on permalloy dots using an iron filled carbon nanotube probe.  


An iron filled carbon nanotube (FeCNT), a 10-40 nm ferromagnetic nanowire enclosed in a protective carbon tube, is an attractive candidate for a magnetic force microscopy (MFM) probe as it provides a mechanically and chemically robust, nanoscale probe. We demonstrate the probe's capabilities with images of the magnetic field gradients close to the surface of a Py dot in both the multi-domain and vortex states. We show the FeCNT probe is accurately described by a single magnetic monopole located at its tip. Its effective magnetic charge is determined by the diameter of the iron wire and its saturation magnetization 4?M(s) ? 2.2 × 10(4)G. A magnetic monopole probe is advantageous as it enables quantitative measurements of the magnetic field gradient close to the sample surface. The lateral resolution is defined by the diameter of the iron wire and the probe-sample separation. PMID:21864777

Wolny, F; Obukhov, Y; Mühl, T; Weissker, U; Philippi, S; Leonhardt, A; Banerjee, P; Reed, A; Xiang, G; Adur, R; Lee, I; Hauser, A J; Yang, F Y; Pelekhov, D V; Büchner, B; Hammel, P C



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


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



Contamination-free imaging by electron induced carbon volatilization in environmental scanning electron microscopy  

NASA Astrophysics Data System (ADS)

Many ultraviolet, x-ray and charged particle beam techniques are inhibited by the growth of carbonaceous films caused by cross linking of hydrocarbon contaminant adsorbates. In electron microscopy, such films obscure surface features and reduce resolution. We demonstrate how resolution degradation can be alleviated using a H2O environment via gas mediated, electron beam induced carbon volatilization, a process that competes with film growth. Net behavior is a function of electron flux, which provides control over growth kinetics during imaging. Under optimized conditions, film growth can be eliminated, removing contamination as a factor limiting image information content and resolution.

Toth, Milos; Lobo, Charlene J.; Lysaght, Michael J.; Vladár, András E.; Postek, Michael T.



Customized patterned substrates for highly versatile correlative light-scanning electron microscopy  

PubMed Central

Correlative light electron microscopy (CLEM) combines the advantages of light and electron microscopy, thus making it possible to follow dynamic events in living cells at nanometre resolution. Various CLEM approaches and devices have been developed, each of which has its own advantages and technical challenges. We here describe our customized patterned glass substrates, which improve the feasibility of correlative fluorescence/confocal and scanning electron microscopy. PMID:25391455

Benedetti, Lorena; Sogne, Elisa; Rodighiero, Simona; Marchesi, Davide; Milani, Paolo; Francolini, Maura



Interactive Stereo Electron Microscopy Enhanced with Virtual Reality LBNL-48336December 17, 2001 1 Interactive Stereo Electron Microscopy Enhanced with Virtual Reality  

E-print Network

image pairs obtained from a scanning electron microscope (SEM). Our system operates by presenting in understanding the pathophysiology at a cellular level of resolution. A Scanning Electron Microscope (SEMInteractive Stereo Electron Microscopy Enhanced with Virtual Reality LBNL-48336December 17, 2001 1


Rapid estimation of catalyst nanoparticle morphology and atomic-coordination by high-resolution Z-contrast electron microscopy.  


Heterogeneous nanoparticle catalyst development relies on an understanding of their structure-property relationships, ideally at atomic resolution and in three-dimensions. Current transmission electron microscopy techniques such as discrete tomography can provide this but require multiple images of each nanoparticle and are incompatible with samples that change under electron irradiation or with surveying large numbers of particles to gain significant statistics. Here, we make use of recent advances in quantitative dark-field scanning transmission electron microscopy to count the number atoms in each atomic column of a single image from a platinum nanoparticle. These atom-counts, along with the prior knowledge of the face-centered cubic geometry, are used to create atomistic models. An energy minimization is then used to relax the nanoparticle's 3D structure. This rapid approach enables high-throughput statistical studies or the analysis of dynamic processes such as facet-restructuring or particle damage. PMID:25340541

Jones, Lewys; MacArthur, Katherine E; Fauske, Vidar T; van Helvoort, Antonius T J; Nellist, Peter D



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


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



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



Characterization of indium gallium nitride led structures using electron microscopy  

NASA Astrophysics Data System (ADS)

Lighting accounts for a significant portion of our energy consumption, but conversion to more efficient solid state lighting alternatives, namely light emitting diodes (LEDs), has been hampered by a number of technical and scientific hurdles. One of the foremost among these is the lack of an efficient green emitter, necessary for the development of color-mixing LEDs capable of producing warm white light efficiently, without the need for a phosphor down- conversion. (In,Ga)N, has been considered as a suitable candidate, having a range of direct bandgaps encompassing the visible spectrum for the various mixtures of InN and GaN. However, challenges confront the (In,Ga)N system, including lack of well-matched substrates for GaN, and the broad miscibility gap between GaN and InN. These concerns have been addressed by exploitation of nano-scale heteroepitaxy: specifically by growing GaN/(In,Ga)N-based LEDs through a nanoporous mask. With this approach, it is possible to grow individual nanorod LED structures by otherwise very conventional means, yet with negligibly low dislocation densities in the active region, and greater InN incorporation. Such systems were characterized through the use of transmission electron microscopy (TEM). Extensive TEM-based sampling and numerical modeling were employed to demonstrate that the nanorod geometry results in a better than two orders of magnitude reduction in the typically high density of threading dislocations of conventional GaN grown on sapphire. The structure of the pyramidal (In,Ga)N wells deposited on these essentially dislocation free nanorods were characterized as a function of attainable processing parameters, using a combination of TEM, scanning transmission electron microscopy (STEM) and energy dispersive spectroscopy (EDS). Optoelectronic measurements confirmed that the nanoscale geometry was effective at in incorporating higher than typical concentrations of InN, with preliminary devices emitting in the yellow- orange. Unexpected planar defects and phase transitions were observed and characterized as a function of processing conditions. TEM was used to demonstrate that new dislocations practically never nucleated within the pyramids---despite the encapsulated, strained (In,Ga)N layer and the frequent planar defects---confirming that dislocation-free nanoscale LED devices based on the nanorod design are a promising possibility.

Colby, Robert


Development of two-photon fluorescence microscopy for quantitative imaging in turbid tissues  

NASA Astrophysics Data System (ADS)

Two-photon laser scanning fluorescence microscopy (TPM) is a high resolution, non-invasive biological imaging technique that can be used to image turbid tissues both in vitro and in vivo at depths of several hundred microns. Although TPM has been widely used to image tissue structures, no one has focused on using TPM to extract quantitative information from turbid tissues at depth. As a result, this thesis addresses the quantitative characterization of two-photon signals in turbid media. Initially, a two-photon microscope system is constructed, and two-photon images that validate system performance are obtained. Then TPM is established as an imaging technique that can be used to validate theoretical observations already listed in the literature. In particular, TPM is found to validate the exponential dependence of the fluorescence intensity decay with depth in turbid tissue model systems. Results from these studies next prompted experimental investigation into whether TPM could be used to determine tissue optical properties. Comparing the exponential dependence of the decay with a Monte Carlo model involving tissue optical properties, TPM is shown to be useful for determining the optical properties (total attenuation coefficient) of thick, turbid tissues on a small spatial scale. Next, a role for TPM for studying and optimizing wound healing is demonstrated. In particular, TPM is used to study the effects of perturbations (growth factors, PDT) on extracellular matrix remodeling in artificially engineered skin tissues. Results from these studies combined with tissue contraction studies are shown to demonstrate ways to modulate tissues to optimize the wound healing immune response and reduce scarring. In the end, TPM is shown to be an extremely important quantitative biological imaging technique that can be used to optimize wound repair.

Coleno, Mariah Lee


Quantitation of Glucocorticoid Receptor DNA-Binding Dynamics by Single-Molecule Microscopy and FRAP  

PubMed Central

Recent advances in live cell imaging have provided a wealth of data on the dynamics of transcription factors. However, a consistent quantitative description of these dynamics, explaining how transcription factors find their target sequences in the vast amount of DNA inside the nucleus, is still lacking. In the present study, we have combined two quantitative imaging methods, single-molecule microscopy and fluorescence recovery after photobleaching, to determine the mobility pattern of the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR), two ligand-activated transcription factors. For dexamethasone-activated GR, both techniques showed that approximately half of the population is freely diffusing, while the remaining population is bound to DNA. Of this DNA-bound population about half the GRs appeared to be bound for short periods of time (?0.7 s) and the other half for longer time periods (?2.3 s). A similar pattern of mobility was seen for the MR activated by aldosterone. Inactive receptors (mutant or antagonist-bound receptors) show a decreased DNA binding frequency and duration, but also a higher mobility for the diffusing population. Likely, very brief (?1 ms) interactions with DNA induced by the agonists underlie this difference in diffusion behavior. Surprisingly, different agonists also induce different mobilities of both receptors, presumably due to differences in ligand-induced conformational changes and receptor complex formation. In summary, our data provide a consistent quantitative model of the dynamics of GR and MR, indicating three types of interactions with DNA, which fit into a model in which frequent low-affinity DNA binding facilitates the search for high-affinity target sequences. PMID:24632838

Groeneweg, Femke L.; van Royen, Martin E.; Fenz, Susanne; Keizer, Veer I. P.; Geverts, Bart; Prins, Jurrien; de Kloet, E. Ron; Houtsmuller, Adriaan B.; Schmidt, Thomas S.; Schaaf, Marcel J. M.



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)



Approaching quantitative Zernike phase contrast in full-field transmission hard X-ray microscopy: Origin and reduction of artifacts  

NASA Astrophysics Data System (ADS)

Zernike phase contrast in hard X-ray transmission microscopy provides in-line observation of phase enhanced imaging of weak-absorbing objects. However, the inherent artifacts are the major hurdle to acquire quantitative structural analysis, and may even present misleading information. We explore the origin of these artifacts by frequency analysis in Fourier domain. Subsequently, a simple and flexible method for artifacts reduction well-suited for full-field transmission hard X-ray microscopy based on combination of spectra is proposed. It is demonstrated to yield quantitative local phase maps, with the characteristic artifact patterns reduced.

Yang, Yang; Heine, Ruth; Cheng, Yin; Wang, Chun-Chieh; Song, Yen-Fang; Baumbach, Tilo



Dynamics of cellular response to hypotonic stimulation revealed by quantitative phase microscopy and multi-fractal detrended fluctuation analysis  

NASA Astrophysics Data System (ADS)

Hypotonic stimulation is known to cause morphological changes in cells and also leads to modulation of cellular physiology. In order to evaluate the dynamics of cellular response to hypotonic stimulation, we utilized digital holographic microscopy for quantitative phase microscopy, achieved by a common-path interferometry geometry based on extraction of reference beam by spatial-filtering. Results from live cell investigations demonstrate the capability of this method for dynamic quantitative phase imaging. Further, wavelet and multi-fractal detrended fluctuation analysis revealed that the dynamic phase changes, in response to hypotonic stimulation, are multifractal in nature.

Cardenas, Nelson; Kumar, Satish; Mohanty, Samarendra



Analytical electron microscopy study on gallium nitride systems doped with manganese and iron  

NASA Astrophysics Data System (ADS)

Modulated structures of gallium nitride (GaN) doped with transition metal ions (here Fe, Mn) are investigated by analytical (scanning) transmission electron microscopy to gain insight into the structural arrangement and chemical composition of the material, known to be critically correlated to the magnetic response and hence the functionality of these technologically relevant systems. Three classes of samples are considered: (i) homogeneous (dilute) (Ga, Mn)N; (ii) ?-Mn-doped (Ga, ?-Mn)N and phase separated (Ga, Fe)N, containing Fe-rich nanocrystals. The combination of various microscopic techniques employed, allows for a quantitative determination of the distribution of the magnetic ions in the samples, providing essential information on the structural and chemical asset of these systems.

Meingast, Arno; Navarro Quezada, Andrea; Devillers, Thibaut; Kovács, András; Albu, Mihela; Fladischer, Stefanie; Bonanni, Alberta; Kothleitner, Gerald



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 deg. 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. [CSNSM, Batiment 108, 91405 Orsay Campus (France); Borodin, V. A. [RRC Kurchatov Institute, Kurchatov Sq., 1, 123182 Moscow (Russian Federation); Ganchenkova, M. G. [Helsinki University of Technology, P.O. Box 1100, 02015 Espoo (Finland); Kirk, M. A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)



Recent advances in electron imaging, image interpretation and applications: environmental scanning electron microscopy.  


One of the latest developments in electron microscopy is the environmental scanning electron microscope (ESEM), which enables soft, moist and/or electrically insulating materials to be viewed without pre-treatment, unlike conventional scanning electron microscopy, in which specimens must be solid, dry and usually electrically conductive. Such an advance has significant implications for studies of the 'native' surfaces of specimens including rocks and minerals, polymers, biological tissues and cells, food and pharmaceutical products, precious artefacts and forensic material, for example. Previous types of electron microscopes made scientists think carefully about the physics of electron-beam interactions with specimens and, hence, the interpretation of images. We now face additional factors influencing the emission and detection of electron signals, unique to the imaging of specimens in the partial vacuum of an ESEM. Just as importantly, we must consider the thermodynamic and kinetic stability of specimens, as appropriate, and explore the possibilities for new applications, particularly those of a dynamic nature. This paper briefly describes some of the issues involved and reviews the current state of understanding. PMID:14667297

Stokes, Debbie J



Study of titanate nanotubes by X-ray and electron diffraction and electron microscopy  

SciTech Connect

The structure of titanate nanotubes (Ti-NTs) was studied by a combination of powder X-ray diffraction (PXRD), electron diffraction and high resolution transmission electron microscopy (HRTEM). Ti-NTs are prepared by hydrothermal treatment of TiO{sub 2} powder. The structure is identified by powder X-ray diffraction as the one based on the structure of H{sub 2}Ti{sub 2}O{sub 5}·H{sub 2}O phase. The same structure is obtained by projected potential from HRTEM through-focus image series. The structure is verified by simulated PXRD pattern with the aid of the Debye formula. The validity of the model is tested by computing Fourier transformation of a single nanotube which is proportional to measured electron diffraction intensities. A good agreement of this calculation with measured precession electron diffraction data is achieved. - Highlights: • Titanate nanotubes were prepared by hydrothermal method. • X-ray powder diffraction indicated their structure based on that of H{sub 2}Ti{sub 2}O{sub 5}·H{sub 2}O. • Structural model was created with the aid of high-resolution electron microscopy. • The model was verified with electron diffraction data. • X-ray powder diffraction pattern was calculated with the aid of the Debye formula.

Brunatova, Tereza [Charles University, Faculty of Mathematics and Physics, Dept. of Condensed Matter Physics, Prague (Czech Republic); Popelkova, Daniela [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague (Czech Republic); Wan, Wei [Berzelii Center EXSELENT on Porous Materials, Stockholm University, SE-106 91 Stockholm (Sweden); Dept. of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden); Oleynikov, Peter [Dept. of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden); Danis, Stanislav [Charles University, Faculty of Mathematics and Physics, Dept. of Condensed Matter Physics, Prague (Czech Republic); Zou, Xiaodong [Berzelii Center EXSELENT on Porous Materials, Stockholm University, SE-106 91 Stockholm (Sweden); Dept. of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm (Sweden); Kuzel, Radomir, E-mail: [Charles University, Faculty of Mathematics and Physics, Dept. of Condensed Matter Physics, Prague (Czech Republic)



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


Materials properties, such as optical and electronic response, can be greatly enhanced by isolated single dopants. Determining the full three-dimensional single-dopant defect structure and spatial distribution is therefore critical to understanding and adequately tuning functional properties. Combining quantitative Z-contrast scanning transmission electron microscopy images with image simulations, we show the direct determination of the atomic-scale depth location of an optically active, single atom Ce dopant embedded within wurtzite-type AlN. The method represents a powerful new tool for reconstructing three-dimensional information from a single, two-dimensional image. PMID:24646109

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



Sensitivity and spatial resolution for electron-spin-resonance detection by magnetic resonance force microscopy  

E-print Network

The signal intensity of electron spin resonance in magnetic resonance force microscopy MRFM experiments that magnetic resonance force microscopy MRFM is a new 3D imaging technique8,9 with the potential of achieving force microscopy Z. Zhanga) Condensed Matter and Thermal Physics Group, Materials Science and Technology

Hammel, P. Chris


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.



Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors.  


Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors. PMID:23703020

Kehayias, Christopher E; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian



Kelvin probe microscopy and electronic transport measurements in reduced graphene oxide chemical sensors  

NASA Astrophysics Data System (ADS)

Reduced graphene oxide (RGO) is an electronically hybrid material that displays remarkable chemical sensing properties. Here, we present a quantitative analysis of the chemical gating effects in RGO-based chemical sensors. The gas sensing devices are patterned in a field-effect transistor geometry, by dielectrophoretic assembly of RGO platelets between gold electrodes deposited on SiO2/Si substrates. We show that these sensors display highly selective and reversible responses to the measured analytes, as well as fast response and recovery times (tens of seconds). We use combined electronic transport/Kelvin probe microscopy measurements to quantify the amount of charge transferred to RGO due to chemical doping when the device is exposed to electron-acceptor (acetone) and electron-donor (ammonia) analytes. We demonstrate that this method allows us to obtain high-resolution maps of the surface potential and local charge distribution both before and after chemical doping, to identify local gate-susceptible areas on the RGO surface, and to directly extract the contact resistance between the RGO and the metallic electrodes. The method presented is general, suggesting that these results have important implications for building graphene and other nanomaterial-based chemical sensors.

Kehayias, Christopher E.; MacNaughton, Samuel; Sonkusale, Sameer; Staii, Cristian



Cryogenic Transmission Electron Microscopy Nanostructural Study of Shed Microparticles  

PubMed Central

Microparticles (MPs) are sub-micron membrane vesicles (100–1000 nm) shed from normal and pathologic cells due to stimulation or apoptosis. MPs can be found in the peripheral blood circulation of healthy individuals, whereas elevated concentrations are found in pregnancy and in a variety of diseases. Also, MPs participate in physiological processes, e.g., coagulation, inflammation, and angiogenesis. Since their clinical properties are important, we have developed a new methodology based on nano-imaging that provides significant new data on MPs nanostructure, their composition and function. We are among the first to characterize by direct-imaging cryogenic transmitting electron microscopy (cryo-TEM) the near-to-native nanostructure of MP systems isolated from different cell types and stimulation procedures. We found that there are no major differences between the MP systems we have studied, as most particles were spherical, with diameters from 200 to 400 nm. However, each MP population is very heterogeneous, showing diverse morphologies. We investigated by cryo-TEM the effects of standard techniques used to isolate and store MPs, and found that either high-g centrifugation of MPs for isolation purposes, or slow freezing to –80°C for storage introduce morphological artifacts, which can influence MP nanostructure, and thus affect the efficiency of these particles as future diagnostic tools. PMID:24386253

Issman, Liron; Brenner, Benjamin; Talmon, Yeshayahu; Aharon, Anat



Candidate sampling for neuron reconstruction from anisotropic electron microscopy volumes.  


The automatic reconstruction of neurons from stacks of electron microscopy sections is an important computer vision problem in neuroscience. Recent advances are based on a two step approach: First, a set of possible 2D neuron candidates is generated for each section independently based on membrane predictions of a local classifier. Second, the candidates of all sections of the stack are fed to a neuron tracker that selects and connects them in 3D to yield a reconstruction. The accuracy of the result is currently limited by the quality of the generated candidates. In this paper, we propose to replace the heuristic set of candidates used in previous methods with samples drawn from a conditional random field (CRF) that is trained to label sections of neural tissue. We show on a stack of Drosophila melanogaster neural tissue that neuron candidates generated with our method produce 30% less reconstruction errors than current candidate generation methods. Two properties of our CRF are crucial for the accuracy and applicability of our method: (1) The CRF models the orientation of membranes to produce more plausible neuron candidates. (2) The interactions in the CRF are restricted to form a bipartite graph, which allows a great sampling speed-up without loss of accuracy. PMID:25333096

Funke, Jan; Martel, Julien N P; Gerhard, Stephan; Andres, Bjoern; Cire?an, Dan C; Giusti, Alessandro; Gambardella, Luca M; Schmidhuber, Jürgen; Pfister, Hanspeter; Cardona, Albert; Cook, Matthew



EMAN2: an extensible image processing suite for electron microscopy.  


EMAN is a scientific image processing package with a particular focus on single particle reconstruction from transmission electron microscopy (TEM) images. It was first released in 1999, and new versions have been released typically 2-3 times each year since that time. EMAN2 has been under development for the last two years, with a completely refactored image processing library, and a wide range of features to make it much more flexible and extensible than EMAN1. The user-level programs are better documented, more straightforward to use, and written in the Python scripting language, so advanced users can modify the programs' behavior without any recompilation. A completely rewritten 3D transformation class simplifies translation between Euler angle standards and symmetry conventions. The core C++ library has over 500 functions for image processing and associated tasks, and it is modular with introspection capabilities, so programmers can add new algorithms with minimal effort and programs can incorporate new capabilities automatically. Finally, a flexible new parallelism system has been designed to address the shortcomings in the rigid system in EMAN1. PMID:16859925

Tang, Guang; Peng, Liwei; Baldwin, Philip R; Mann, Deepinder S; Jiang, Wen; Rees, Ian; Ludtke, Steven J




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



Hybrid Electron Microscopy Normal Mode Analysis graphical interface and protocol.  


This article presents an integral graphical interface to the Hybrid Electron Microscopy Normal Mode Analysis (HEMNMA) approach that was developed for capturing continuous motions of large macromolecular complexes from single-particle EM images. HEMNMA was shown to be a good approach to analyze multiple conformations of a macromolecular complex but it could not be widely used in the EM field due to a lack of an integral interface. In particular, its use required switching among different software sources as well as selecting modes for image analysis was difficult without the graphical interface. The graphical interface was thus developed to simplify the practical use of HEMNMA. It is implemented in the open-source software package Xmipp 3.1 ( and only a small part of it relies on MATLAB that is accessible through the main interface. Such integration provides the user with an easy way to perform the analysis of macromolecular dynamics and forms a direct connection to the single-particle reconstruction process. A step-by-step HEMNMA protocol with the graphical interface is given in full details in Supplementary material. The graphical interface will be useful to experimentalists who are interested in studies of continuous conformational changes of macromolecular complexes beyond the modeling of continuous heterogeneity in single particle reconstruction. PMID:25268657

Sorzano, Carlos Oscar S; de la Rosa-Trevín, José Miguel; Tama, Florence; Joni?, Slavica



Analytical electron microscopy of biogenic and inorganic carbonates  

NASA Technical Reports Server (NTRS)

In the terrestrial sedimentary environment, the mineralogically predominant carbonates are calcite-type minerals (rhombohedral carbonates) and aragonite-type minerals (orthorhombic carbonates). Most common minerals precipitating either inorganically or biogenically are high magnesium calcite and aragonite. High magnesium calcite (with magnesium carbonate substituting for more than 7 mole percent of the calcium carbonate) is stable only at temperatures greater than 700 C or thereabouts, and aragonite is stable only at pressures exceeding several kilobars of confining pressure. Therefore, these carbonates are expected to undergo chemical stabilization in the diagenetic environment to ultimately form stable calcite and dolomite. Because of the strong organic control of carbonate deposition in organisms during biomineralization, the microchemistry and microstructure of invertebrate skeletal material is much different than that present in inorganic carbonate cements. The style of preservation of microstructural features in skeletal material is therefore often quite distinctive when compared to that of inorganic carbonate even though wholesale recrystallization of the sediment has taken place. Microstructural and microchemical comparisons are made between high magnesium calcite echinoderm skeletal material and modern inorganic high magnesium calcite inorganic cements, using analytical electron microscopy and related techniques. Similar comparisons are made between analogous materials which have undergone stabilization in the diagenetic environment. Similar analysis schemes may prove useful in distinguishing between biogenic and inorganic carbonates in returned Martian carbonate samples.

Blake, David F.



Transmission electron microscopy (TEM) study of minerals in coal  

SciTech Connect

Minerals in eight coals from different mines were characterized in the micron-size range by using analytical transmission electron microscopy. Specimens were thinned by ion-milling wafers cut from these coals; a cold stage cooled by liquid nitrogen was used to reduce thermal degradation of the minerals by the ion-beam. Different mineral compounds were observed in different coals. The major minerals are clays, sulfides, oxides, carbonates and some minor-element-bearing phosphates. Clays (kaolinite, illite and others) have been most commonly found as either flat sheets or round globules. Iron sulfide was mostly found in the No. 5 and No. 6 coals from Illinois, distributed as massive polycrystals, as clusters of single crystals (framboids) or as isolated single crystals with size range down to some 0.25 microns. Other sulfides and some oxides were found in other coals with particle size as small as some 200 angstroms. Quartz, titanium oxides and many other carbonates and phosphate compounds were also characterized. Brief TEM work in the organic mass of coal was also introduced to study the nature of the coal macerals.

Hsieh, Kuang-Chien



Atomic force microscopy and scanning electron microscopy analysis of daily disposable limbal ring contact lenses  

PubMed Central

Background Limbal ring (also known as ‘circle’) contact lenses are becoming increasingly popular, especially in Asian markets because of their eye-enhancing effects. The pigment particles that give the eye-enhancing effects of these lenses can be found on the front or back surface of the contact lens or ‘enclosed’ within the lens matrix. The purpose of this research was to evaluate the pigment location and surface roughness of seven types of ‘circle’ contact lenses. Methods Scanning electron microscopic (SEM) analysis was performed using a variable pressure Hitachi S3400N instrument to discern the placement of lens pigments. Atomic force microscopy (Dimension Icon AFM from Bruker Nano) was used to determine the surface roughness of the pigmented regions of the contact lenses. Atomic force microscopic analysis was performed in fluid phase under contact mode using a Sharp Nitride Lever probe (SNL-10) with a spring constant of 0.06 N/m. Root mean square (RMS) roughness values were analysed using a generalised linear mixed model with a log-normal distribution. Least square means and their corresponding 95% confidence intervals were estimated for each brand, location and pigment combination. Results SEM cross-sectional images at 500× and 2,000× magnification showed pigment on the surface of six of the seven lens types tested. The mean depth of pigment for 1-DAY ACUVUE DEFINE (1DAD) lenses was 8.1??m below the surface of the lens, while the remaining lens types tested had pigment particles on the front or back surface. Results of the atomic force microscopic analysis indicated that 1DAD lenses had significantly lower root mean square roughness values in the pigmented area of the lens than the other lens types tested. Conclusions SEM and AFM analysis revealed pigment on the surface of the lens for all types tested with the exception of 1DAD. Further research is required to determine if the difference in pigment location influences on-eye performance. PMID:24689948

Lorenz, Kathrine Osborn; Kakkassery, Joseph; Boree, Danielle; Pinto, David



High brightness electron sources for MeV ultrafast diffraction and microscopy  

NASA Astrophysics Data System (ADS)

In this paper we review the present status of MeV electron sources for ultrafast diffraction and microscopy applications and trace the path forward to improve the spatio-temporal resolution of electron scattering probes.

Musumeci, P.; Li, R. K.



Ultrastructure of Hybrid ChitosanGlycerol Phosphate Blood Clots by Environmental Scanning Electron Microscopy  

E-print Network

Ultrastructure of Hybrid Chitosan­Glycerol Phosphate Blood Clots by Environmental Scanning Electron chitosan; chitosan­glycerol phosphate; biomaterials; blood; glutaraldehyde; paraformaldehyde; environmental scanning electron microscopy; cartilage repair; arthritis ABSTRACT Chitosan-based polymers have been

Buschmann, Michael


Nonlinear optical microscopy: use of second harmonic generation and two-photon microscopy for automated quantitative liver fibrosis studies  

E-print Network

Liver fibrosis is associated with an abnormal increase in an extracellular matrix in chronic liver diseases. Quantitative characterization of fibrillar collagen in intact tissue is essential for both fibrosis studies and ...

Sun, Wanxin


Serial block face scanning electron microscopy for the study of cardiac muscle ultrastructure at nanoscale resolutions.  


Electron microscopy techniques have made a significant contribution towards understanding muscle physiology since the 1950s. Subsequent advances in hardware and software have led to major breakthroughs in terms of image resolution as well as the ability to generate three-dimensional (3D) data essential for linking structure to function and dysfunction. In this methodological review we consider the application of a relatively new technique, serial block face scanning electron microscopy (SBF-SEM), for the study of cardiac muscle morphology. Employing SBF-SEM we have generated 3D data for cardiac myocytes within the myocardium with a voxel size of ~15nm in the X-Y plane and 50nm in the Z-direction. We describe how SBF-SEM can be used in conjunction with selective staining techniques to reveal the 3D cellular organisation and the relationship between the t-tubule (t-t) and sarcoplasmic reticulum (SR) networks. These methods describe how SBF-SEM can be used to provide qualitative data to investigate the organisation of the dyad, a specialised calcium microdomain formed between the t-ts and the junctional portion of the SR (jSR). We further describe how image analysis methods may be applied to interrogate the 3D volumes to provide quantitative data such as the volume of the cell occupied by the t-t and SR membranes and the volumes and surface area of jSR patches. We consider the strengths and weaknesses of the SBF-SEM technique, pitfalls in sample preparation together with tips and methods for image analysis. By providing a 'big picture' view at high resolutions, in comparison to conventional confocal microscopy, SBF-SEM represents a paradigm shift for imaging cellular networks in their native environment. PMID:25149127

Pinali, Christian; Kitmitto, Ashraf



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)



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

NASA Astrophysics Data System (ADS)

Superhydrophobic surfaces (SHSs) show promise as promoters of dropwise condensation. Droplets with diameters below ˜10 ?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.; Fedorov, A. G.



In situ transmission electron microscopy of electron-beam induced damage process in nuclear grade graphite  

SciTech Connect

Atomic level processes involved in the swelling and crack-closing in nuclear grade graphite under electron irradiation have been observed in real-time using transmission electron microscopy. Noise-filtered lattice images show the formation of vacancy loops, interstitial loops and resulting dislocations with unprecedented clarity. The dislocation dipoles formed via vacancy loops were found to undergo climb resulting in extra basal planes. Concurrent EELS studies showed a reduction in the atomic density because of the breakage of hexagonal carbon rings. The formation of new basal planes via dislocation climb in addition to the bending/breaking of basal planes leads to swelling and closing of micro-cracks.

C. Karthik; J. Kane; D. P. Butt; W. E. Windes; R. Ubic



Electron diffraction and microscopy study of nanotubes and nanowires  

NASA Astrophysics Data System (ADS)

Carbon nanotubes have many excellent properties that are strongly influenced by their atomic structure. The realization of the ultimate potential of carbon nanotubes in technological applications necessitates a precise control of the structure of as-grown nanotubes as well as the identification of their atomic structures. Transmission electron microscopy (TEM) is a technique that can deliver this by combining the high resolution imaging and electron diffraction simultaneously. In this study, a new catalyst system (the Co/Si) was investigated in the production of single-walled carbon nanotubes (SWNTs) by laser ablation. It was discovered that the Co/Si mixture as a catalyst was as successful as the Ni/Co in the synthesis of SWNTs. The isolated individual SWNTs were examined by using nanobeam electron diffraction for the structure identification and it was found that carbon nanotubes grown by this catalyst mixture tend to be slightly more metallic. The electron diffraction technique has been refined to establish a new methodology to determine the chirality of each shell in a carbon nanotube and it has been applied to determine the atomic structure of double-walled carbon nanotubes (DWNT), few-walled carbon nanotubes (FWNT) and multi-walled carbon nanotubes (MWNT). We observed that there is no strong correlation in the structure of two adjacent shells in DWNTs. Several FWNTs and MWNTs have been examined by our new electron diffraction method to determine their atomic structures and to test the efficiency and the reliability of this method for structure identification. We now suggest that a carbon nanotube of up to 25 shells can be studied and the chirality of each shell can be identified by this new technique. The guidelines for the automation of such procedure have been laid down and explained in this work. The atomic structure of tungsten disulfide (WS2) nanotubes was studied by using the methods developed for the structure determination of carbon nanotubes. The WS2 nanotubes are another example of the tube forming ability of the layered structures and a member of the family of inorganic fullerene-like structures. These nanotubes are much larger in diameter than carbon nanotubes. The tubes studied here have helicities less than 18° and usually have near zigzag structure. The short-range order (SRO) in the atomic structure of carbon soot produced by laser ablation was investigated using electron diffraction and radial distribution function (RDF) analysis. The effects of the furnace temperature and the metal catalyst on the SRO in the carbon soot were also studied. It was discovered that the SRO structure is the same for all carbon soot samples studied and is very similar to that of amorphous carbon. These techniques were also applied to determine the atomic structure of amorphous boron nanowires. We found out that the atomic structure of these boron nanowires agree well with the previously reported structure of bulk amorphous boron.

Deniz, Hakan


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.)



Biominerals at the nanoscale: transmission electron microscopy methods for studying the special properties of biominerals  

E-print Network

Biominerals at the nanoscale: transmission electron microscopy methods for studying the special, calcite and aragonite are used by many organisms for making shells, and magnetite helps bacteria and birds, strictly controlled physical and chemical properties. Transmission electron microscopy is ideally suited

Dunin-Borkowski, Rafal E.



E-print Network

REPRESENTATION THEORETIC PATTERNS IN THREE DIMENSIONAL CRYO-ELECTRON MICROSCOPY III - PRESENCE-dimensional structure determination of large biological molecules from cryo-electron microscopy pro- jection images of many important molecules such as various complex of proteins and exterior shells of viruses. Symmetric

Gurevich, Shamgar



E-print Network

REPRESENTATION THEORETIC PATTERNS IN THREE DIMENSIONAL CRYO-ELECTRON MICROSCOPY III - PRESENCE-dimensional structure deter- mination of large biological molecules from cryo-electron microscopy projection images and exterior shells of viruses. Symmetric biological molecules, usually appear as complexes, composed

Gurevich, Shamgar


Heparin binding sites on Ross River virus revealed by electron cryo-microscopy  

E-print Network

Heparin binding sites on Ross River virus revealed by electron cryo-microscopy Wei Zhang, Marintha complex with heparin were determined through the use of electron cryo-microscopy and image reconstruction methods. Heparin was found to bind at the distal end of the RRV spikes, in a region of the E2 glycoprotein

Baker, Timothy S.


Spermiogenesis and spermatozoon of Echinostoma caproni ( Platyhelminthes, Digenea): transmission and scanning electron microscopy, and tubulin immunocytochemistry  

Microsoft Academic Search

Spermiogenesis and the spermatozoon of Echinostoma caproni (from experimentally infested laboratory mice) were investigated by several methods. Transmission electron microscopy shows that spermiogenesis consists of a proximo-distal fusion of three processes followed by elongation of the spermatid. Scanning electron microscopy shows that the spermatozoon is a filiform cell, 235 ?m in length, with a cylindrical anterior extremity and a broader

C. Iomini; J.-L. Justine



Electron Microscopy of Structures Present in Embryonic Cells of Plants Infected with Plum Pox Virus  

Microsoft Academic Search

Polák J. , Jokeš M. , Duchá?ová M. , Hauptmanová A., Komínek P. (2008): Electron microscopy of structures present in embryonic cells of plants infected with Plum pox virus. Plant Protect. Sci., 44: 81-84. Electron microscopy was used to detect the presence of virus particles or inclusions in growth tips and paren - chymatic cells of leaves of plum, apricot

Jaroslav Polák


Simplified setup for imaging with digital holographic microscopy and enhanced quantitative phase contrast by osmotic stimulation of living cells  

NASA Astrophysics Data System (ADS)

Many interferometry-based quantitative phase contrast imaging techniques require the generation of a coherent reference wave, which results in a phase stability decrease and the demand for a precise adjustment of the intensity ratio between object and reference wave. Thus, investigations on a simplified digital holographic microscopy approach that avoids a separate reference wave were performed. Results from live cell investigations demonstrate the capability of the method for quantitative phase contrast imaging. In further experiments the modification of the intracellular refractive index distribution by osmotic stimulation was analyzed. Data from human pancreas tumor cells show that by choice of suitable buffer solutions live cell imaging with enhanced quantitative phase contrast is achieved.

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



3D quantitative elemental mapping using simultaneous proton induced X-ray emission tomography and scanning transmission ion microscopy tomography  

NASA Astrophysics Data System (ADS)

A technique has been implemented that could produce sub-micron resolution quantitative elemental mapping of cells in an acceptable time frame. A new experimental set-up was installed to produce 3D quantitative elemental maps of biological samples by combining simultaneous proton induced X-ray emission tomography (PIXE-T), on/off-axis scanning transmission ion microscopy tomography (STIM-T) and Rutherford backscattering spectrometry (RBS). Combined with a high efficiency Si(Li) detector, 3D quantitative maps of Cl, S, Ca, K, Fe and Zn in a section of a hair were produced with an analytical time of 3 h.

Beasley, Daniel; Spyrou, Nicholas M.



XMIPP: a new generation of an open-source image processing package for electron microscopy  

Microsoft Academic Search

X-windows based microscopy image processing package (Xmipp) is a specialized suit of image processing programs, primarily aimed at obtaining the 3D reconstruction of biological specimens from large sets of projection images acquired by transmission electron microscopy. This public-domain software package was introduced to the electron microscopy field eight years ago, and since then it has changed drastically. New methodologies for

C. O. S. Sorzano; R. Marabini; J. Velázquez-Muriel; J. R. Bilbao-Castro; S. H. W. Scheres; J. M. Carazo; A. Pascual-Montano



Correlated cryo-fluorescence and cryo-electron microscopy with high spatial precision and improved sensitivity.  


Performing fluorescence microscopy and electron microscopy on the same sample allows fluorescent signals to be used to identify and locate features of interest for subsequent imaging by electron microscopy. To carry out such correlative microscopy on vitrified samples appropriate for structural cryo-electron microscopy it is necessary to perform fluorescence microscopy at liquid-nitrogen temperatures. Here we describe an adaptation of a cryo-light microscopy stage to permit use of high-numerical aperture objectives. This allows high-sensitivity and high-resolution fluorescence microscopy of vitrified samples. We describe and apply a correlative cryo-fluorescence and cryo-electron microscopy workflow together with a fiducial bead-based image correlation procedure. This procedure allows us to locate fluorescent bacteriophages in cryo-electron microscopy images with an accuracy on the order of 50 nm, based on their fluorescent signal. It will allow the user to precisely and unambiguously identify and locate objects and events for subsequent high-resolution structural study, based on fluorescent signals. PMID:24275379

Schorb, Martin; Briggs, John A G



Quantitative determination of maximal imaging depth in all-NIR multiphoton microscopy images of thick tissues  

NASA Astrophysics Data System (ADS)

We report two methods for quantitatively determining maximal imaging depth from thick tissue images captured using all-near-infrared (NIR) multiphoton microscopy (MPM). All-NIR MPM is performed using 1550 nm laser excitation with NIR detection. This method enables imaging more than five-fold deep in thick tissues in comparison with other NIR excitation microscopy methods. In this study, we show a correlation between the multiphoton signal along the depth of tissue samples and the shape of the corresponding empirical probability density function (pdf) of the photon counts. Histograms from this analysis become increasingly symmetric with the imaging depth. This distribution transitions toward the background distribution at higher imaging depths. Inspired by these observations, we propose two independent methods based on which one can automatically determine maximal imaging depth in the all-NIR MPM images of thick tissues. At this point, the signal strength is expected to be weak and similar to the background. The first method suggests the maximal imaging depth corresponds to the deepest image plane where the ratio between the mean and median of the empirical photon-count pdf is outside the vicinity of 1. The second method suggests the maximal imaging depth corresponds to the deepest image plane where the squared distance between the empirical photon-count mean obtained from the object and the mean obtained from the background is greater than a threshold. We demonstrate the application of these methods in all-NIR MPM images of mouse kidney tissues to study maximal depth penetration in such tissues.

Sarder, Pinaki; Akers, Walter J.; Sudlow, Gail P.; Yazdanfar, Siavash; Achilefu, Samuel




PubMed Central

A pre-Columbian Peruvian scalp was examined decades ago by a researcher from the Oswaldo Cruz Foundation. Professor Olympio da Fonseca Filho described nits and adult lice attached to hair shafts and commented about the origin of head lice infestations on mankind. This same scalp was sent to our laboratory and is the subject of the present paper. Analysis showed a massive infestation with nine eggs/cm2 and an impressive number of very well preserved adult lice. The infestation age was roughly estimated as nine months before death based on the distance of nits from the hair root and the medium rate of hair growth. A small traditional textile was associated with the scalp, possibly part of the funerary belongings. Other morphological aspects visualized by low-vacuum scanning electron microscopy are also presented here for adults and nits. PMID:24626412

Dutra, Juliana M.F.; Alves, Arthur Daniel; Pessanha, Thaila; Rachid, Rachel; de Souza, Wanderley; Linardi, Pedro Marcos; Ferreira, Luiz Fernando; de Souza, Sheila Mendonça; Araujo, Adauto



High resolution electron microscopy of interfaces in fcc materials  

SciTech Connect

Modern high-resolution electron microscopy (HREM) instruments, which are capable of a point-to-point resolution of better than 0.2 nm, have allowed atomic-scale observations of a variety of internal interfaces. The application of the HREM technique to fcc model systems for the purpose of addressing a number of interface issues will be examined in this paper. Atomic structure observations for heterophase interfaces of metal/metal and metal/metal-oxide systems as well as HREM studies of grain boundaries in NiO and Au will be discussed with emphasis on generic structural features and the role of the interface plane. Comparisons between observed interface structures and atomistic computer modeling results have shown agreements for some interfaces, as well as certain differences in others. A number of structural features are common to both metal and oxide grain boundaries, as well as certain heterophase boundaries. Of particular importance in close-packed solids appears to be the tendency to preserve, as much as possible, local atomic coordination, giving rise to atomically well-matched regions that alternate along the interface with regions of misfit. It is commonly observed that heterophase interfaces are being preferentially formed on dense-packed planes. Low-index planes are also frequently observed in asymmetric grain boundaries. In addition to the observation of misfit dislocations in heterophase boundaries, misfit-dislocation-like defects have also been found in asymmetric, incommensurate grain boundaries. The tendency for maintaining coherence between dense-packed planes across the interface has resulted in the formation of novel three-dimensional GB structures. HREM observations have brought new insights into the correlations between macroscopic geometry, interfacial energy, and microscopic atomic relaxations.

Merkle, K.L.



[Tegumental ultrastructures of Echinostoma hortense observed by scanning electron microscopy  


The tegumental ultrastructures of Echinostoma hortense adults were observed by scanning electron microscopy. The worms of 4 weeks of age were harvested from albino rats experimentally infected with the metacercariae obtained from the loach. The results were as follows: The worms were leaf-like and their anterior end portion, including oral sucker and head crown, ventrally curved to face posteriorly. The tegument of whole body was wrinkled transversely and covered with cobblestone-like cytoplasmic processes. The oral sucker had roundly swollen (type II) sensory papillae on the ventral half of its lip and uni-ciliated knob-like (type I) sensory papillae, arranged in 2-3 rows, on the dorsal outer surface. Aspinous ventral sucker had many of type I papillae arranged in a circular band on its outer surface. The tegument around the genital opening was of similar feature to the ventral sucker, but sensory papillae were hardly found around the former. Scale-like spines with broad base and round tip were distributed densely on the tegument anterior to the ventral sucker but they became sparse in posterior half of the ventral surface, finally to disappear at posterior extremity. A few number of type I papillae were observed on the ventral surface. The results suggest that the tegument of E. hortense is similar to that of other echinostomes especially E. revolutum. But the number and arrangement of collar spines, and/or the type and distribution of sensory papillae seem characteristic features of E. hortense differed from other echinostomes. PMID:12886109

Lee, Soon Hyung; Hong, Sung Jong; Chai, Jong Yil; Hong, Sung Tae; Seo, Byong Seol



EDITORIAL: Electron Microscopy and Analysis Group Conference 2013 (EMAG2013)  

NASA Astrophysics Data System (ADS)

It has once again been my pleasure to act as editor for these proceedings, and I must thank all those who have acted as reviewers. I am always struck by the scientific quality of the oral and poster contributions and the vibrant discussions that occur both in the formal sessions and in the exhibition space at EMAG. I am convinced that a crucial part of maintaining that scientific quality is the opportunity that is offered of having a paper fully reviewed by two internationally selected referees and published in the Journal of Physics: Conference Series. For many students, this is the first fully reviewed paper they publish. I hope that, like me, you will be struck by the scientific quality of the 80 papers that follow, and that you will find them interesting and informative. I must also personally thank all the organisers of EMAG2013 for arranging such an excellent meeting. Ian MacLaren, as Chair of the EMAG Group and of the meeting itself, has contributed a foreword to these proceedings describing the meeting in more detail. A particular highlight of the conference was the special symposium in honour of Professor Archie Howie. We all enjoyed a wonderful speech from Archie at the conference dinner, along with some of his electron microscopy-related poetry. I have great pleasure in publishing the conference dinner poems in this proceedings. I hope you will find these proceedings to be an interesting read and an invaluable resource. Pete Nellist Conference committee Conference chair: Dr I MacLaren Programme organiser: Dr C Ducati Proceedings editor: Prof P D Nellist Trade exhibition organiser: C Hockey (CEM Group) Local organisers: Professor E Boyes, Professor P Gai, Dr R Kröger, Dr V Lazarov, Dr P O'Toole, Dr S Tear and Professor J Yuan Advanced school organisers: Dr S Haigh, Dr A Brown Other committee members: Mr K Meade, Mr O Heyning, Dr M Crawford, Mr M Dixon and Dr Z Li

Nellist, Pete



Transmission Electron Microscopy of Iron Metal in Almahata Sitta Ureilite  

NASA Technical Reports Server (NTRS)

Almahata Sitta (AS) is a polymict breccia mainly composed of variable ureilite lithologies with small amounts of chondritic lithologies [1]. Fe metal is a common accessory phase in ureilites, but our earlier study on Fe metals in one of AS fragments (#44) revealed a unique mineralogy never seen in other ureilites [2,3]. In this abstract we report detailed transmission electron microscopy (TEM) on these metal grains to better understand the thermal history of ureilites. We prepared FIB sections of AS#44 by JEOL JIB-4000 from the PTS that was well characterized by SEM-EBSD in our earlier study [2]. The sections were then observed by STEM (JEOL JEM- 2100F). One of the FIB sections shows a submicron-sized symplectic intergrown texture composed of Fe metal (kamacite), Fe carbide (cohenite), Fe phosphide (schreibersite), and Fe sulfide (troilite). Each phase has an identical SAED pattern in spite of its complex texture, suggesting co-crystallization of all phases. This is probably caused by shock re-melting of pre-existing metal + graphite to form a eutectic-looking texture. The other FIB section is mostly composed of homogeneous Fe metal (93 wt% Fe, 5 wt% Ni, and 2 wt% Si), but BF-STEM images exhibited the presence of elongated lathy grains (approx. 2 microns long) embedded in the interstitial matrix. The SAED patterns from these lath grains could be indexed by alpha-Fe (bcc) while interstitial areas are gamma-Fe (fcc). The elongated alpha-Fe grains show tweed-like structures suggesting martensite transformation. Such a texture can be formed by rapid cooling from high temperature where gamma-Fe was stable. Subsequently alpha-Fe crystallized, but gamma-Fe remained in the interstitial matrix due to quenching from high temperature. This scenario is consistent with very rapid cooling history of ureilites suggested by silicate mineralogy.

Mikouchi, T.; Yubuta, K.; Sugiyama, K.; Aoyagi, Y.; Yasuhara, A.; Mihira, T.; Zolensky, M. E.; Goodrich, C. A.



Functional Materials characterizations by Scanning/Transmission Electron Microscopy and Electron Energy Loss spectroscopy  

NASA Astrophysics Data System (ADS)

Along with the fast development of science and technology, the studied materials are becoming more complicated and smaller. All these achievements have advanced with the fast development of powerful tools currently, such as Scanning electron microscopy (SEM), Focused Ion Beam (FIB), Transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), Electron energy loss spectroscopy (EELS) and so on. SiTiO3 thin film, which is grown on Si (100) single crystals, attracts a lot of interest in its structural and electronic properties close to its interface. Valence EELS is used to investigate the Plasmon excitations of the ultrathin SrTiO3 thin film which is sandwiched between amorphous Si and crystalline Si layers. On the other hand, theoretical simulations based on dielectric functions have been done to interpret the experimental results. Our findings demonstrate the value of valence electron energy-loss spectroscopy in detecting a local change in the effective electron mass. Recently it is reported that ZnO-LiYbO2 hybrid phosphor is an efficient UV-infrared convertor for silicon solar cell but the mechanism is still not very clear. The microstructure of Li and Yb co-doped ZnO has been studied by SEM and EDX, and our results suggest that a reaction (or diffusion) zone is very likely to exist between LiYbO2 and ZnO. Such diffusion regions may be responsible for the enhanced infrared emission in the Yb and Li co-doped ZnO. Furthermore, to help us study the diffusion zone under TEM in future, the radiation damage on synthesized LiYbO2 has been studied at first, and then the electronic structure of the synthesized LiYbO2 is compared with Yb2O 3 experimentally and theoretically, by EELS and FEFF8 respectively.

Yang, Bo


Nanoscale Electronic Inhomogeneity in In_2Se_3 Nanoribbons Revealed by Microwave Impedance Microscopy  

SciTech Connect

Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides and chalcogenides, these microscopic phases are of great scientific and technological importance for research in hightemperature superconductors, colossal magnetoresistance effect, phase-change memories, and domain switching operations. Direct imaging on dielectric properties of these local phases,however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In{sub 2}Se{sub 3}) nanoribbons by near-field scanning microwave impedance microscopy. Multiple phases with local resistivity spanning six orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with {approx}100nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform quantitative sub-surface electronic study in a noninvasive manner. Finally, the phase change memory function in In{sub 2}Se{sub 3} nanoribbon devices can be locally recorded with big signal of opposite signs.

Lai, K.J.



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.



Visualization of Microbial Biomarkers by Scanning Electron Microscopy  

NASA Technical Reports Server (NTRS)

We are developing tools to link the biochemical structure of selected biomarkers with putative biogenic structures observed in mineralized samples. The detection of evidence of life on Mars and other planets will rely on methods that can discriminate compounds formed exclusively by living organisms. While biogenic compounds, such as amino acids and nucleotides have been discovered in extraterrestrial sources, such as meteorites and comets, their formation can be explained by abiotic means. The formation of cellular structures, or more elaborate organic molecules, such as complex lipids, proteins or nucleic acids, however, is strongly correlated to the presence of even the most primitive life processes. Recent evidence lends support to the hypothesis that life may have once existed on Mars. Carbonate globules and ppm concentrations of polycyclic aromatic hydrocarbons (PAHs) have been described in ALH84001, a meteorite originating from Mars ejecta captured by Earth over 13,000 years ago. The localized high concentration of PAHs that follow an increasing gradient from the intact fusion crust towards the interior corresponds to microgram quantities of hydrocarbon. Even though ALH84001 and other similar meteorites have withstood the forces capable of ejecting rock through Mars' escape velocity, upon entering Earth's atmosphere, their core temperatures are likely not to have been raised significantly, as evidenced by the survival of remanent magnetic signatures. Ideal biomarkers of ancient or modern biological life would include molecules that are (or were) pervasive and highly resistant to degradation. Also, requisite methods of detection should be simple, extremely sensitive and broadly inclusive (NASA SP-530). Lipopolysaccharide (LPS), peptidoglycan or pseudopeptidoglycan and beta-glucan are microbial cell wall components which together cover the entire microbial spectrum of eubacteria, archea and fungi. They are all remarkably resistant to thermal degradation. Fortunately, many antimicrobial defense systems of higher organisms require sensitive detection to combat microbial pathogens. We employ here the primitive immune system of the evolutionarily ancient horseshoe crab, Limulus polyphemus. This species relies on multi-enzyme signal amplification detection of cell wall molecules and they can be applied to the development of useful detectors of life. An extension of this work includes the visualization of microbial signatures by labeling LAL components with chromogenic or electron dense markers. The protein Limulus Anti-LPS Factor (LALF) has an extremely high affinity for LPS. By coupling LALF binding with colloidal gold labels we demonstrate a correlation of the structures visible by electron microscopy with biochemical evidence of microbial cell wall materials. Pure silica particles were mixed with cultures of E. coli (10(exp 6) cfu/mL). Samples were washed sequentially with buffered saline, LALF, antibody to LALF and finally colloidal gold-labeled Protein A. Negative controls were not exposed to E. coli but received identical treatment otherwise. Samples were coated with carbon and imaged on a JEOL JSM-840 scanning electron microscope with LaB6 source in the back scatter mode with the JEOL annular back scatter detector. 20 nm-scale black spots in this contrast-reversed image originate from electrons back-scattered by gold atoms. Negative controls did not give any signal. Future work will expand application of this technique to soil simulants and mineralized rock samples.

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



Solution structure and direct imaging of fibronectin adsorption to solid surfaces by scanning force microscopy and cryo-electron microscopy.  


In this study, we present the scanning force and electron microscopic visualization of single molecules of fibronectin either frozen hydrated or adsorbed onto metallic and polymeric surfaces with different solid surface tensions. The surfaces were characterized by dynamic contact angle measurements, X-ray photo emission spectroscopy (XPS or ESCA) and scanning force microscopy. The proteins were prepared by fast protein liquid chromatography (FPLC) and characterized by gel electrophoresis. Protein films on surfaces were investigated by surface plasmon resonance spectroscopy and directly imaged by scanning force microscopy. The spreading of the adsorbed fibronectin revealed dependence on the chemical composition and the solid surface tension. Structure of fibronectin in solution as well as on solid interface appeared as an extended straight strand as obtained by imaging with electron and scanning probe microscopies. Imaging of DNA was performed by scanning force microscopy to test the accuracy and reproducibility of our measurements. The measured contour lengths were accurate and the larger widths were caused by convolution of the tip shape and sample. Frictional forces during the scan have been of significant contribution in the imaging mechanism. Moreover, this work demonstrated that scanning force microscopy can be used for mapping the orientation and organization of protein film adsorbed onto various surfaces at the nanoscale. PMID:8176331

Zenhausern, F; Adrian, M; Descouts, P



ANG-2 for quantitative Na(+) determination in living cells by time-resolved fluorescence microscopy.  


Sodium ions (Na(+)) play an important role in a plethora of cellular processes, which are complex and partly still unexplored. For the investigation of these processes and quantification of intracellular Na(+) concentrations ([Na(+)]i), two-photon coupled fluorescence lifetime imaging microscopy (2P-FLIM) was performed in the salivary glands of the cockroach Periplaneta americana. For this, the novel Na(+)-sensitive fluorescent dye Asante NaTRIUM Green-2 (ANG-2) was evaluated, both in vitro and in situ. In this context, absorption coefficients, fluorescence quantum yields and 2P action cross-sections were determined for the first time. ANG-2 was 2P-excitable over a broad spectral range and displayed fluorescence in the visible spectral range. Although the fluorescence decay behaviour of ANG-2 was triexponential in vitro, its analysis indicates a Na(+)-sensitivity appropriate for recordings in living cells. The Na(+)-sensitivity was reduced in situ, but the biexponential fluorescence decay behaviour could be successfully analysed in terms of quantitative [Na(+)]i recordings. Thus, physiological 2P-FLIM measurements revealed a dopamine-induced [Na(+)]i rise in cockroach salivary gland cells, which was dependent on a Na(+)-K(+)-2Cl(-) cotransporter (NKCC) activity. It was concluded that ANG-2 is a promising new sodium indicator applicable for diverse biological systems. PMID:25311309

Roder, Phillip; Hille, Carsten



Quantitative Imaging of Rapidly Decaying Evanescent Fields Using Plasmonic Near-Field Scanning Optical Microscopy  

PubMed Central

Non-propagating evanescent fields play an important role in the development of nano-photonic devices. While detecting the evanescent fields in far-field can be accomplished by coupling it to the propagating waves, in practice they are measured in the presence of unwanted propagating background components. It leads to a poor signal-to-noise ratio and thus to errors in quantitative analysis of the local evanescent fields. Here we report on a plasmonic near-field scanning optical microscopy (p-NSOM) technique that incorporates a nanofocusing probe for adiabatic focusing of propagating surface plasmon polaritons at the probe apex, and for enhanced coupling of evanescent waves to the far-field. In addition, a harmonic demodulation technique is employed to suppress the contribution of the background. Our experimental results show strong evidence of background free near-field imaging using the new p-NSOM technique. Furthermore, we present measurements of surface plasmon cavity modes, and quantify their contributing sources using an analytical model. PMID:24076563

Zhang, Zhen; Ahn, Phillip; Dong, Biqin; Balogun, Oluwaseyi; Sun, Cheng



Polarization second harmonic generation microscopy provides quantitative enhanced molecular specificity for tissue diagnostics.  


Due to specific structural organization at the molecular level, several biomolecules (e.g., collagen, myosin etc.) which are strong generators of second harmonic generation (SHG) signals, exhibit unique responses depending on the polarization of the excitation light. By using the polarization second harmonic generation (p-SHG) technique, the values of the second order susceptibility components can be used to differentiate the types of molecule, which cannot be done by the use of a standard SHG intensity image. In this report we discuss how to implement p-SHG on a commercial multiphoton microscope and overcome potential artifacts in susceptibility (?) image. Furthermore we explore the potential of p-SHG microscopy by applying the technique to different types of tissue in order to determine corresponding reference values of the ratio of second-order ? tensor elements. These values may be used as a bio-marker to detect any structural alterations in pathological tissue for diagnostic purposes. The SHG intensity image (red) in (a) shows the distribution of collagen fibers in ovary tissue but cannot determine the type of collagen fiber. However, the histogram distribution (b) for the values of the ? tensor element ratio can be used to quantitatively identify the types of collagen fibers. PMID:25363416

Kumar, Rajesh; Grønhaug, Kirsten M; Romijn, Elisabeth I; Finnøy, Andreas; Davies, Catharina L; Drogset, Jon O; Lilledahl, Magnus B



Microscopy, Culture, and Quantitative Real-Time PCR Examination Confirm Internalization of Mycobacteria in Plants  

PubMed Central

The environment is a reservoir of nontuberculous mycobacteria and is considered a source of infection for animals and humans. Mycobacteria can persist in different types of environments for a relatively long time. We have studied their possible internalization into plant tissue through intact, as well as damaged, root systems of different types of plants grown in vitro and under field conditions. The substrate into which plants were seeded was previously contaminated with different strains of Mycobacterium avium (108 to 1010 cells/g of soil) and feces from animals with paratuberculosis. We detected M. avium subsp. avium, hominissuis, and paratuberculosis in the stems and leaves of the plants by both culture and real-time quantitative PCR. The presence of mycobacteria in the plant tissues was confirmed by microscopy. The concentration of mycobacteria found inside plant tissue was several orders of magnitude lower (up to 104 cells/g of tissue) than the initial concentration of mycobacteria present in the culture medium or substrate. These findings led us to the hypothesis that plants may play a role in the spread and transmission of mycobacteria to other organisms in the environment. PMID:24747896

Lvoncik, S.; Slana, I.; Kulich, P.; Kralik, P.



Nanoparticle interactions with live cells: Quantitative fluorescence microscopy of nanoparticle size effects  

PubMed Central

Summary Engineered nanomaterials are known to enter human cells, often via active endocytosis. Mechanistic details of the interactions between nanoparticles (NPs) with cells are still not well enough understood. NP size is a key parameter that controls the endocytic mechanism and affects the cellular uptake yield. Therefore, we have systematically analyzed the cellular uptake of fluorescent NPs in the size range of 3.3–100 nm (diameter) by live cells. By using spinning disk confocal microscopy in combination with quantitative image analysis, we studied the time courses of NP association with the cell membrane and subsequent internalization. NPs with diameters of less than 10 nm were observed to accumulate at the plasma membrane before being internalized by the cells. In contrast, larger NPs (100 nm) were directly internalized without prior accumulation at the plasma membrane, regardless of their surface charges. We attribute this distinct size dependence to the requirement of a sufficiently strong local interaction of the NPs with the endocytic machinery in order to trigger the subsequent internalization.

Shang, Li; Nienhaus, Karin; Jiang, Xiue; Yang, Linxiao; Landfester, Katharina; Mailänder, Volker; Simmet, Thomas



Characterization of gold nanoparticle films: Rutherford backscattering spectroscopy, scanning electron microscopy with image analysis, and atomic force microscopy  

SciTech Connect

Gold nanoparticle films are of interest in several branches of science and technology, and accurate sample characterization is needed but technically demanding. We prepared such films by DC magnetron sputtering and recorded their mass thickness by Rutherford backscattering spectroscopy. The geometric thickness d{sub g}—from the substrate to the tops of the nanoparticles—was obtained by scanning electron microscopy (SEM) combined with image analysis as well as by atomic force microscopy (AFM). The various techniques yielded an internally consistent characterization of the films. In particular, very similar results for d{sub g} were obtained by SEM with image analysis and by AFM.

Lansåker, Pia C., E-mail:; Niklasson, Gunnar A.; Granqvist, Claes G. [Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, P. O. Box 534, SE-751 21 Uppsala (Sweden); Hallén, Anders [Royal Institute of Technology, KTH-ICT, Elektrum 229, Kista, SE-164 40 Stockholm (Sweden)



Backscattered Electron Microscopy as an Advanced Technique in Petrography.  

ERIC Educational Resources Information Center

Three uses of this method with sandstone, desert varnish, and granite weathering are described. Background information on this technique is provided. Advantages of this type of microscopy are stressed. (CW)

Krinsley, David Henry; Manley, Curtis Robert



Scanned Probe Microscopy of Electronic Transport in Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We use electrostatic force microscopy and scanned gate microscopy to probe the conducting properties of carbon nanotubes at room temperature. Multiwalled carbon nanotubes are shown to be diffusive conductors, while metallic single-walled carbon nanotubes are ballistic conductors over micron lengths. Semiconducting single-walled carbon nanotubes are shown to have a series of large barriers to conduction along their length. These measurements are also used to probe the contact resistance and locate breaks in carbon nanotube circuits.

Bachtold, A.; Fuhrer, M. S.; Plyasunov, S.; Forero, M.; Anderson, Erik H.; Zettl, A.; McEuen, Paul L.



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. PMID:18447528

Downing, Kenneth H.; Mooney, Paul E.



Transmission electron microscopy studies of longitudinal magnetic recording materials  

NASA Astrophysics Data System (ADS)

I describe three studies of materials with potential applications in computer hard drives: the aim of each study was to understand what microstructural features are required for further increases in recording storage density. In the first study, we used Lorentz Transmission Electron Microscopy (LTEM) to observe the magnetic structure of bits on real hard disks. We wanted to determine how the microstructure affects one's ability to store closely spaced, sharp magnetic-transitions. We used Fresnel-mode-LTEM to observe three disks, which had different hysteresis behaviors and microstructures. We also observed one of the disks using Fresnel-mode-LTEM, Foucault-mode-LTEM, and conventional-mode TEM. In so doing, we were able to observe the magnetic structure of the bits and the physical structure of the magnetic film from the same region of the disk. All of the images from both LTEM modes, however, were of low resolution, which we ascribe to a combination of the moderate Mrt of the disks and the limitations of the microscope. I also discuss the future of LTEM for studying low- Mrt disks. In the second study, we attempted to deposit Fe16N2, which has potential in the write head as a core material. We developed a technique to sputter deposit epitaxial (001) Fe-based compounds on(001) Si substrates using a Ag buffer layer. In our efforts, we grew the disordered parent phase to Fe16N2, alpha' nitrogen-martensite, in epitaxial and single phase form. Although we did observe a partial transformation (˜30 volume %) to the ordered Fe16N2 in alpha ' films after post-deposition annealing, we did not observe any Fe16N2 in the as-deposited films. In the third study we observed the thin barrier layer in magnetic tunneling junctions (MTJs) using cross-sectional TEM. We studied how AlOx barriers are formed on Co and PtMnSb. We investigated how position on the substrate, oxidation time, oxygen plasma character, precursor Al thickness, and bottom electrode material affect the final barrier thickness, spread in thickness, and MTJ performance. We show that each of these parameters must be optimized to fabricate high performance MTJs.

Clark, Trevor Edward


Rapid simultaneous identification and quantitation of Staphylococcus aureus and Pseudomonas aeruginosa directly from bronchoalveolar lavage specimens using automated microscopy.  


Diagnosis of ventilator-assisted pneumonia (VAP) requires pathogen quantitation of respiratory samples. Current quantitative culture methods require overnight growth, and pathogen identification requires an additional step. Automated microscopy can perform rapid simultaneous identification and quantitation of live, surface-immobilized bacteria extracted directly from patient specimens using image data collected over 3 h. Automated microscopy was compared to 1 ?L loop culture and standard identification methods for Staphylococcus aureus and Pseudomonas spp. in 53 remnant bronchoalveolar lavage specimens. Microscopy identified 9/9 S. aureus and 7/7 P. aeruginosa in all specimens with content above the VAP diagnostic threshold. Concordance for specimens containing targets above the diagnostic threshold was 13/16, with concordance for sub-diagnostic content of 86/90. Results demonstrated that automated microscopy had higher precision than 1 ?L loop culture (range ~0.55 log versus ?1 log), with a dynamic range of ~4 logs (~10(3) to 10(6) CFU/mL). PMID:24698367

Metzger, Steven; Frobel, Rachel A; Dunne, W Michael



Electron Microscopy 1.0 Introduction and History  

E-print Network

in 1931. · The first Scanning Electron Microscope (SEM) debuted in 1938 ( Von Ardenne) with the first of Results #12;o Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale. o Electron Microscopes were developed due

Moeck, Peter


Enhanced quantitative confocal microscopy and its application for the measurement of tympanic membrane thickness  

NASA Astrophysics Data System (ADS)

This work shows that confocal microscopy allows a quantitative study of delicate 3D-biotissue in fresh condition, thus avoiding histological preparation processes. The developed procedure results in exact and accurate thickness data for mum-sized objects with a measuring error of less than 1mum. It is, however, necessary to take into account the effect of focal shift in the case of refractive index mismatch to obtain such precise data. The use of the proposed method is advised instead of the use of a paraxial approximation for the axial scale correction because the method improves measurement precision by a factor of four. The axial scaling correction factors obtained in this work show that for most practical situations the correction cannot be ignored when one wants to obtain precise quantitative data. The thickness correction method can also be used to determine with high accuracy the index of refraction of biological tissue. The thickness measurement method was applied to fresh, untreated tympanic membranes of the gerbil, the cat and the human. Thickness had to be measured at many points as it differs strongly across the membrane. Similar thickness distributions were found in all pars tensas measured even across the species studied: (1) a very thin, central region with a rather constant thickness, curving as a horse shoe upwards around the manubrium (thickness: gerbil: about 7mum, cat: about 10mum, human: large inter-specimen variation: 40mum-120mum), (2) a thinnest zone at the inferior side, (3) a thicker zone at the supero-anterior side, (4) superior to the umbo, an anterior region thicker than the posterior region, (5) maximal thicknesses in a very small region near the entire manubrium and the entire annular periphery. The pars flaccida is found to be thicker than the pars tensa. It shows no central homogeneous zone: the thickness varies irregularly and very rapidly over short distances. Arbitrarily spaced bumps and notches are present over the entire pars flaccida surface. The thickness results advise against the use of single thickness values in mathematical models. The presented thickness and its spatial distribution can be introduced into middle ear computer models to further improve model realism.

Kuypers, Liesbeth



A workflow for the automatic segmentation of organelles in electron microscopy image stacks  

PubMed Central

Electron microscopy (EM) facilitates analysis of the form, distribution, and functional status of key organelle systems in various pathological processes, including those associated with neurodegenerative disease. Such EM data often provide important new insights into the underlying disease mechanisms. The development of more accurate and efficient methods to quantify changes in subcellular microanatomy has already proven key to understanding the pathogenesis of Parkinson's and Alzheimer's diseases, as well as glaucoma. While our ability to acquire large volumes of 3D EM data is progressing rapidly, more advanced analysis tools are needed to assist in measuring precise three-dimensional morphologies of organelles within data sets that can include hundreds to thousands of whole cells. Although new imaging instrument throughputs can exceed teravoxels of data per day, image segmentation and analysis remain significant bottlenecks to achieving quantitative descriptions of whole cell structural organellomes. Here, we present a novel method for the automatic segmentation of organelles in 3D EM image stacks. Segmentations are generated using only 2D image information, making the method suitable for anisotropic imaging techniques such as serial block-face scanning electron microscopy (SBEM). Additionally, no assumptions about 3D organelle morphology are made, ensuring the method can be easily expanded to any number of structurally and functionally diverse organelles. Following the presentation of our algorithm, we validate its performance by assessing the segmentation accuracy of different organelle targets in an example SBEM dataset and demonstrate that it can be efficiently parallelized on supercomputing resources, resulting in a dramatic reduction in runtime. PMID:25426032

Perez, Alex J.; Seyedhosseini, Mojtaba; Deerinck, Thomas J.; Bushong, Eric A.; Panda, Satchidananda; Tasdizen, Tolga; Ellisman, Mark H.



Fast imaging with inelastically scattered electrons by off-axis chromatic confocal electron microscopy.  


We introduce off-axis chromatic scanning confocal electron microscopy, a technique for fast mapping of inelastically scattered electrons in a scanning transmission electron microscope without a spectrometer. The off-axis confocal mode enables the inelastically scattered electrons to be chromatically dispersed both parallel and perpendicular to the optic axis. This enables electrons with different energy losses to be separated and detected in the image plane, enabling efficient energy filtering in a confocal mode with an integrating detector. We describe the experimental configuration and demonstrate the method with nanoscale core-loss chemical mapping of silver (M4,5) in an aluminium-silver alloy and atomic scale imaging of the low intensity core-loss La (M4,5@840??eV) signal in LaB6. Scan rates up to 2 orders of magnitude faster than conventional methods were used, enabling a corresponding reduction in radiation dose and increase in the field of view. If coupled with the enhanced depth and lateral resolution of the incoherent confocal configuration, this offers an approach for nanoscale three-dimensional chemical mapping. PMID:24815659

Zheng, Changlin; Zhu, Ye; Lazar, Sorin; Etheridge, Joanne



Quantitative scheme for full-field polarization rotating fluorescence microscopy using a liquid crystal variable retarder  

PubMed Central

We present a quantitative scheme for full-field polarization rotating fluorescence microscopy. A quarter-wave plate, in combination with a liquid crystal variable retarder, provides a tunable method to rotate polarization states of light prior to its being coupled into a fluorescence microscope. A calibration of the polarization properties of the incident light is performed in order to correct for elliptical polarization states. This calibration allows the response of the sample to linear polarization states of light to be recovered. Three known polarization states of light can be used to determine the average fluorescent dipole orientations in the presence of a spatially varying dc offset or background polarization-invariant fluorescence signal. To demonstrate the capabilities of this device, we measured a series of full-field fluorescence polarization images from fluorescent analogs incorporated in the lipid membrane of Burkitts lymphoma CA46 cells. The fluorescent lipid-like analogs used in this study are molecules that are labeled by either a DiI (1,1?-Dioctadecyl 3,3,3?,3?-Tetramethylindocarbocyanine) fluorophore in its head group or a Bodipy (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) molecule in its acyl chain. A spatially varying contrast in the normalized amplitude was observed on the cell surface, where the orientation of the DiI molecules is tangential to the cell membrane. The internally labeled cellular structures showed zero response to changes in linear polarization, and the net linear polarization amplitude for these regions was zero. This instrument provides a low cost calibrated method that may be coupled to existing fluorescence microscopes to perform investigations of cellular processes that involve a change in molecular orientations. PMID:22667623

Lesoine, John F.; Youn Lee, Ji; Krogmeier, Jeffrey R.; Kang, Hyeonggon; Clarke, Matthew L.; Chang, Robert; Sackett, Dan L.; Nossal, Ralph; Hwang, Jeeseong



Atomic Force Microscopy of Red-Light Photoreceptors Using PeakForce Quantitative Nanomechanical Property Mapping.  


Atomic force microscopy (AFM) uses a pyramidal tip attached to a cantilever to probe the force response of a surface. The deflections of the tip can be measured to ~10 pN by a laser and sectored detector, which can be converted to image topography. Amplitude modulation or "tapping mode" AFM involves the probe making intermittent contact with the surface while oscillating at its resonant frequency to produce an image. Used in conjunction with a fluid cell, tapping-mode AFM enables the imaging of biological macromolecules such as proteins in physiologically relevant conditions. Tapping-mode AFM requires manual tuning of the probe and frequent adjustments of a multitude of scanning parameters which can be challenging for inexperienced users. To obtain high-quality images, these adjustments are the most time consuming. PeakForce Quantitative Nanomechanical Property Mapping (PF-QNM) produces an image by measuring a force response curve for every point of contact with the sample. With ScanAsyst software, PF-QNM can be automated. This software adjusts the set-point, drive frequency, scan rate, gains, and other important scanning parameters automatically for a given sample. Not only does this process protect both fragile probes and samples, it significantly reduces the time required to obtain high resolution images. PF-QNM is compatible for AFM imaging in fluid; therefore, it has extensive application for imaging biologically relevant materials. The method presented in this paper describes the application of PF-QNM to obtain images of a bacterial red-light photoreceptor, RpBphP3 (P3), from photosynthetic R. palustris in its light-adapted state. Using this method, individual protein dimers of P3 and aggregates of dimers have been observed on a mica surface in the presence of an imaging buffer. With appropriate adjustments to surface and/or solution concentration, this method may be generally applied to other biologically relevant macromolecules and soft materials. PMID:25407118

Kroeger, Marie E; Sorenson, Blaire A; Thomas, J Santoro; Stojkovi?, Emina A; Tsonchev, Stefan; Nicholson, Kenneth T



In Situ Transmission Electron Microscopy of Lead Dendrites and Lead Ions in Aqueous Solution  

PubMed Central

An ideal technique for observing nanoscale assembly would provide atomic-resolution images of both the products and the reactants in real time. Using a transmission electron microscope (TEM) we image in situ the electrochemical deposition of lead from an aqueous solution of lead(II) nitrate. Both the lead deposits and the local Pb2+ concentration can be visualized. Depending on the rate of potential change and the potential history, lead deposits on the cathode in a structurally compact layer or in dendrites. In both cases the deposits can be removed and the process repeated. Asperities that persist through many plating and stripping cycles consistently nucleate larger dendrites. Quantitative digital image analysis reveals excellent correlation between changes in the Pb2+ concentration, the rate of lead deposition, and the current passed by the electrochemical cell. Real-time electron microscopy of dendritic growth dynamics and the associated local ionic concentrations can provide new insight into the functional electrochemistry of batteries and related energy storage technologies. PMID:22702348

White, Edward R.; Singer, Scott B.; Augustyn, Veronica; Hubbard, William A.; Mecklenburg, Matthew; Dunn, Bruce; Regan, Brian C.



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 that a micropattern of ClAlPc ultrathin film prepared on the MoS{sub 2} 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. {copyright} 2001 American Institute of Physics.

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



Transmission electron microscopy of thiol-capped Au clusters on C: Structure and electron irradiation effects.  


High-resolution transmission electron microscopy is used to study interactions between thiol-capped Au clusters and amorphous C support films. The morphologies of the clusters are found to depend both on their size and on the local structure of the underlying C. When the C is amorphous, larger Au clusters are crystalline, while smaller clusters are typically disordered. When the C is graphitic, the Au particles adopt either elongated shapes that maximize their contact with the edge of the C film or planar arrays when they contain few Au atoms. We demonstrate the influence of electron beam irradiation on the structure, shape and stability of the Au clusters, as well as on the formation of holes bounded by terraces of graphitic lamellae in the underlying C. PMID:25554918

Gontard, Lionel C; Dunin-Borkowski, Rafal E



Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells  

PubMed Central

Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 ?m for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM) [Gilbert et al., Journal of the American Chemical Society 2008, 130:17519–17527]. Polarized optical microscopy revealed unprecedented super-structures in the calcitic shell part. This bears, in principle, the potential for in vivo studies, which might be useful for investigating the growth modes of nacre and other shell types. PMID:22967319



A Quantitative 3D Motility Analysis of Trypanosoma brucei by Use of Digital In-line Holographic Microscopy  

PubMed Central

We present a quantitative 3D analysis of the motility of the blood parasite Trypanosoma brucei. Digital in-line holographic microscopy has been used to track single cells with high temporal and spatial accuracy to obtain quantitative data on their behavior. Comparing bloodstream form and insect form trypanosomes as well as mutant and wildtype cells under varying external conditions we were able to derive a general two-state-run-and-tumble-model for trypanosome motility. Differences in the motility of distinct strains indicate that adaption of the trypanosomes to their natural environments involves a change in their mode of swimming. PMID:22629379

Weiße, Sebastian; Heddergott, Niko; Heydt, Matthias; Pflästerer, Daniel; Maier, Timo; Haraszti, Tamás; Grunze, Michael; Engstler, Markus; Rosenhahn, Axel



A quantitative 3D motility analysis of Trypanosoma brucei by use of digital in-line holographic microscopy.  


We present a quantitative 3D analysis of the motility of the blood parasite Trypanosoma brucei. Digital in-line holographic microscopy has been used to track single cells with high temporal and spatial accuracy to obtain quantitative data on their behavior. Comparing bloodstream form and insect form trypanosomes as well as mutant and wildtype cells under varying external conditions we were able to derive a general two-state-run-and-tumble-model for trypanosome motility. Differences in the motility of distinct strains indicate that adaption of the trypanosomes to their natural environments involves a change in their mode of swimming. PMID:22629379

Weiße, Sebastian; Heddergott, Niko; Heydt, Matthias; Pflästerer, Daniel; Maier, Timo; Haraszti, Tamás; Grunze, Michael; Engstler, Markus; Rosenhahn, Axel



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

PubMed Central

Recently, three-dimensional reconstruction of ultrastructure of the brain has been realized with minimal effort by using scanning electron microscopy (SEM) combined with focused ion beam (FIB) milling (FIB-SEM). Application of immunohistochemical staining in electron microscopy (EM) provides a great advantage in that molecules of interest are specifically localized in ultrastructures. Thus, we applied immunocytochemistry for FIB-SEM and correlated this immunoreactivity with that in confocal laser-scanning microcopy (CF-LSM). Dendrites of medium-sized spiny neurons in the rat neostriatum were visualized using a recombinant viral vector, which labeled the infected neurons with membrane-targeted GFP in a Golgi stain-like fashion. Moreover, the thalamostriatal afferent terminals were immunolabeled with Cy5 fluorescence for vesicular glutamate transporter 2 (VGluT2). After detection of the sites of terminals apposed to the dendrites by using CF-LSM, GFP and VGluT2 immunoreactivities were further developed for EM by using immunogold/silver enhancement and immunoperoxidase/diaminobenzidine (DAB) methods, respectively. In contrast-inverted FIB-SEM images, silver precipitations and DAB deposits were observed as fine dark grains and diffuse dense profiles, respectively, indicating that these immunoreactivities were as easily recognizable as those in the transmission electron microscopy (TEM) images. Furthermore, in the sites of interest, some appositions displayed synaptic specializations of an asymmetric type. Thus, the present method was useful in the three-dimensional analysis of immunocytochemically differentiated synaptic connections in the central neural circuit. PMID:23443927

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



Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-Ray (EDX) Spectroscopy  

E-print Network

Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-Ray (EDX) Spectroscopy The materials characterization facility is equipped with a Hitachi S-4700 Field Emission Scanning Electron Electron Microscope (FE-SEM). The FE-SEM is equipped with EDAX Energy Dispersive X-Ray (EDX) spectroscopy

Gelfond, Michael


Investigating the Optical Properties of Dislocations by Scanning Transmission Electron Microscopy  

E-print Network

, Tennessee Summary: The scanning transmission electron microscope (STEM) allows collection of a number (EBIC) modes of the scanning electron microscope (SEM) (Chase and Holt 1973; Datta et al. 1977; DavidsonInvestigating the Optical Properties of Dislocations by Scanning Transmission Electron Microscopy S

Pennycook, Steve


An apparatus for imaging liquids, cells, and other wet samples in the scanning electron microscopy  

E-print Network

capability for the imaging of wet samples in the scanning electron microscope SEM , a need that arises is furthermore easily adaptable to all existing scanning electron microscopes, en- abling measurements of wetAn apparatus for imaging liquids, cells, and other wet samples in the scanning electron microscopy

Moses, Elisha


Investigation of Nanoelectrodes by Transmission Electron Microscopy M.S. Kabir1  

E-print Network

or impossible to image with atomic force microscopes (AFM) or Scanning Electron Microscopes (SEM). We have and investigated their properties in transmission electron microscope (TEM) and their electrical characteristicsInvestigation of Nanoelectrodes by Transmission Electron Microscopy M.S. Kabir1 , S.H. Magnus

Boyer, Edmond


Atherosclerotic alterations in human carotid observed by scanning electron microscopy.  


Atherosclerosis involves all the layers of the artery wall, but the events involving the intimal portion are fundamental to understand the evolution and gravity of lesions. This study shows that scanning microscopy is instrumental for better understanding the physiopathology of this disease. PMID:21072990

Dell'Orbo, Carlo; Quacci, Daniela; Raspanti, Mario; Congiu, Terenzio; Reguzzoni, Marcella; Protasoni, Marina



Microscopic techniques bridging between nanoscale and microscale with an atomically sharpened tip - field ion microscopy/scanning probe microscopy/ scanning electron microscopy.  


Over a hundred years an atomistic point of view has been indispensable to explore fascinating properties of various materials and to develop novel functional materials. High-resolution microscopies, rapidly developed during the period, have taken central roles in promoting materials science and related techniques to observe and analyze the materials. As microscopies with the capability of atom-imaging, field ion microscopy (FIM), scanning tunneling microscopy (STM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) can be cited, which have been highly evaluated as methods to ultimately bring forward the viewpoint of reductionism in materials science. On one hand, there have been difficulties to derive useful and practical information on large (micro) scale unique properties of materials using these excellent microscopies and to directly advance the engineering for practical materials. To make bridges over the gap between an atomic scale and an industrial engineering scale, we have to develop emergence science step-by-step as a discipline having hierarchical structures for future prospects by combining nanoscale and microscale techniques; as promising ways, the combined microscopic instruments covering the scale gap and the extremely sophisticated methods for sample preparation seem to be required. In addition, it is noted that spectroscopic and theoretical methods should implement the emergence science.Fundamentally, the function of microscope is to determine the spatial positions of a finite piece of material, that is, ultimately individual atoms, at an extremely high resolution with a high stability. To define and control the atomic positions, the STM and AFM as scanning probe microscopy (SPM) have successfully demonstrated their power; the technological heart of SPM lies in an atomically sharpened tip, which can be observed by FIM and TEM. For emergence science we would like to set sail using the tip as a base. Meanwhile, it is significant to extend a model sample prepared for the microscopies towards a microscale sample while keeping the intrinsic properties found by the microscopies.In this study we present our trial of developing microscopic combined instruments among FIM, field emission microscopy (FEM), STM, AFM and scanning electron microscopy (SEM), in which we prepared and characterized the tips for the SPM, and in addition, the sample preparation to take a correlation between nanoscale and microscale properties of functional materials. Recently, we developed a simple sample preparation method of a rutile single crystal TiO2 covered with an epitaxially-grown monolayer of SiO2 by annealing the crystals in a furnace at high temperatures in air; the crystal samples were placed into a quartz container in the furnace [1]. The vapor of SiO evaporated from the quartz container were adsorbed on the crystal while the crystal surfaces being fully oxidized in air. The SiO2-TiO2 composite systems are promising to protect catalytic TiO2 performance; the photo-catalytic activity is kept by coating with hard and stable SiO2 layers and to extend the lifetime of water super-hydrophilicity even in dark, though understanding of their properties is insufficient due to the lack of techniques to fabricate a well-characterized system on a nanoscale to conduct control experiments. The SiO2 overlayers were observed by low energy electron diffraction (LEED) in vacuum and frequency-modulation (FM) AFM in water [1,2], and water contact angles (WCA) were measured [2]. Although the WCA measurement seems a classic characterization, this method possesses a high potential to make a bridge by controlling the environmental conditions. We will discuss the details. PMID:25359799

Tomitori, Masahiko; Sasahara, Akira



Scanning electron microscopy of legs of two species of sucking lice (Anoplura: Phthiraptera)  

Microsoft Academic Search

Pretarsal, tarsal and tibial structures of the forelegs, midlegs and hindlegs of Pediculus humanus of humans and of Haematopinus apri Goureau, 1866 (Phthiraptera), a parasite of feral hogs, were studied using light microscopy and scanning electron microscopy. Details of the tibial thumb-like process (tl) with the spine of the thumb (spn), tarsal apophysis (ta) and the coupled finger-like process (cfl)

M. D. Soler Cruz; M. P. Martín Mateo



Diffusive and inelastic scattering in ballistic-electron-emission spectroscopy and ballistic-electron-emission microscopy  

SciTech Connect

Ballistic-electron-emission microscopy (BEEM) of Au/Si(001) n type was done to study whether elastic scattering in the Au overlayer is dominant. It was found that there is no dependence of the BEEM current on the relative gradient of the Au surface with respect to the Si interface, and this demonstrates that significant elastic scattering must occur in the Au overlayer. Ballistic-electron-emission spectroscopy (BEES) was also done, and, rather than using the conventional direct-current BEES, alternating-current (ac) BEES was done on Au/Si and also on Au/PtSi/Si(001) n type. The technique of ac BEES was found to give linear threshold for the Schottky barrier, and it also clearly showed the onset of electron-hole pair creation and other inelastic scattering events. The study of device quality PtSi in Au/PtSi/Si(001) yielded an attenuation length of 4 nm for electrons of energy 1 eV above the PtSi Fermi energy. 20 refs., 5 figs.

Lee, E.Y.; Turner, B.R.; Schowalter, L.J. [Rensselaer Polytechnic Institute, Troy, NY (United States)] [and others] [Rensselaer Polytechnic Institute, Troy, NY (United States); and others



Twin-beams digital holography for 3D tracking and quantitative phase-contrast microscopy in microfluidics.  


We report on a compact twin-beam interferometer that can be adopted as a flexible diagnostic tool in microfluidic platforms with twofold functionality. The novel configuration allows 3D tracking of micro-particles and, at same time, can simultaneously furnish Quantitative Phase-contrast maps of tracked micro-objects by interference microscopy, without changing the configuration. Experimental demonstration is given on for in vitro cells in a microfluidic environment. PMID:22273976

Memmolo, Pasquale; Finizio, Andrea; Paturzo, Melania; Miccio, Lisa; Ferraro, Pietro




EPA Science Inventory

Concerns about the environmental and public health effects of particulate matter (PM) have stimulated interest in analytical techniques capable of measuring the size and chemical composition of individual aerosol particles. Computer-controlled scanning electron microscopy (CCSE...



EPA Science Inventory

Giardia trophozoites were isolated from the small intestine of budgerigars (parakeets) and examined morphologically with light and scanning electron microscopy. The presence of a claw-hammer shape median body suggested classification of these trophozoites as G. duodenalis. Howeve...


Segmentation and registration of molecular components in 3-dimensional density maps from cryo-electron microscopy  

E-print Network

Cryo-electron microscopy is a method that produces 3D density maps of macromolecular complexes. Segmentation and registration methods are heavily used to extract structural information from such density maps. Segmentation ...

Pintilie, Grigore Dimitrie, 1976-



Demonstration of Ballistic Electron Emission Microscopy / Spectroscopy on the Au/Si (001) system  

E-print Network

The Ballistic Electron Emission Microscopy (BEEM) capabilities of a Scanning Tunneling Microscope (STM) have been verified. BEEM is used to analyze the characteristics of buried energy barriers and was developed as an extension of scanning tunneling...

Drummond, Mary Alyssa



Trace element mapping in Parkinsonian brain by quantitative ion beam microscopy  

NASA Astrophysics Data System (ADS)

The role of iron in the pathogenesis of the Parkinson's disease (PD) is a current subject of research in Neurochemistry, since an abnormal increase in iron is reported in the substantia nigra (SN) of Parkinsonian patients. A severe loss of the cells containing dopamine in the SN in the PD has also drawn attention towards the function of a browny-black pigment called neuromelanin, which accumulates predominantly in these dopaminergic neurons. The neuromelanin has an ability to chelate metal ions, which, in free state, may cause considerable damage to cells by reacting with their lipid-rich membranes. However, it could also potentiate free radical production if it releases the bound metal ions. The highly sensitive and non-destructive micro-PIXE method suits best to quantify and map the trace elements in the SN. The accuracy in charge measurement for such microanalysis studies is of utmost importance for quantitative analysis. Since a Faraday cup is usually placed behind the thin biological sample to measure the charge, the primary and the secondary electrons, knocked out from the sample by traversing ion beam, hamper an exact charge determination. Hence, a new non-interceptive technique was developed for precise charge measurement and for continuous monitoring of beam current.

Barapatre, Nirav; Morawski, Markus; Butz, Tilman; Reinert, Tilo



Structure and magnetism in ultrathin iron oxides characterized by low energy electron microscopy.  


We have grown epitaxial films a few atomic layers thick of iron oxides on ruthenium. We characterize the growth by low energy electron microscopy. Using selected-area diffraction and intensity-versus-voltage spectroscopy, we detect two distinct phases which are assigned as wüstite and magnetite. Spin-polarized low energy electron microscopy reveals magnetic domain patterns in the magnetite phase at room temperature. PMID:21828572

Santos, B; Loginova, E; Mascaraque, A; Schmid, A K; McCarty, K F; de la Figuera, J



Near atomic resolution microanalysis of interfaces by analytical electron microscopy  

SciTech Connect

High spatial resoslution x-ray microanalysis in the analytical electron microscope (AEM) can be used to determine chemical composition on spatial scales of < 50 nm. Simple scattering models have the drawback of being incapable of treating electron scattering in inhomogeneous specimens, such as at phase interfaces or grain boundary segregation. The best method for calculating electron scattering and x-ray generation function is by Mone Carlo methods. Two examples are discussed: a phase interface in an Fe-Ni-Cr alloy, and grain boundary segregation using a 0.3 nm Cu slab in a 25 nm Al film (the slab is parallel to incident electron beam). It is concluded that high spatial resolution x-ray microanalysis can achieve near atomic resolution, but that massively parallel Monte Carlo models for electron scattering and a well characterized electron beam are needed.

Romig, A.D. Jr.; Michael, J.R.



Annealing effects on a high-k lanthanum oxide film on Si (001) analyzed by aberration-corrected transmission electron microscopy/scanning transmission electron microscopy and electron energy loss spectroscopy  

NASA Astrophysics Data System (ADS)

The annealing behavior of a lanthanum oxide thin film deposited on a silicon (001) substrate by electron-beam evaporation has been studied by aberration-corrected transmission electron microscopy (TEM), scanning TEM (STEM), and electron energy loss spectroscopy (EELS). We have developed a procedure for the precise measurement of thickness and interfacial roughness by taking advantage of features of aberration correction combined with the statistics of fluctuating crystalline edge positions. The results of the measurements and quantitative elemental analyses by STEM-EELS have revealed atomic diffusion and reactions during deposition and postdeposition annealing (PDA) at 300 and 500 °C. The channel mobility could be limited by Coulomb scattering before PDA, and by remote roughness scattering and remote phonon scattering after PDA at 500 °C. When we consider the large leakage current caused by oxygen defects in the as-deposited sample and the large equivalent oxide thickness of the thick Si-rich layer in the 500 °C-PDA sample, the gate properties of the 300 °C-PDA sample should be better than those of other samples, as shown by electrical measurements.

Inamoto, S.; Yamasaki, J.; Okunishi, E.; Kakushima, K.; Iwai, H.; Tanaka, N.



Enhanced quantitative phase imaging in self-interference digital holographic microscopy using an electrically focus tunable lens.  


Self-interference digital holographic microscopy (DHM) has been found particular suitable for simplified quantitative phase imaging of living cells. However, a main drawback of the self-interference DHM principle are scattering patterns that are induced by the coherent nature of the laser light which affect the resolution for detection of optical path length changes. We present a simple and efficient technique for the reduction of coherent disturbances in quantitative phase images. Therefore, amplitude and phase of the sample illumination are modulated by an electrically focus tunable lens. The proposed method is in particular convenient with the self-interference DHM concept. Results from the characterization of the method show that a reduction of coherence induced disturbances up to 70 percent can be achieved. Finally, the performance for enhanced quantitative imaging of living cells is demonstrated. PMID:25574433

Schubert, Robin; Vollmer, Angelika; Ketelhut, Steffi; Kemper, Björn



Enhanced quantitative phase imaging in self-interference digital holographic microscopy using an electrically focus tunable lens  

PubMed Central

Self-interference digital holographic microscopy (DHM) has been found particular suitable for simplified quantitative phase imaging of living cells. However, a main drawback of the self-interference DHM principle are scattering patterns that are induced by the coherent nature of the laser light which affect the resolution for detection of optical path length changes. We present a simple and efficient technique for the reduction of coherent disturbances in quantitative phase images. Therefore, amplitude and phase of the sample illumination are modulated by an electrically focus tunable lens. The proposed method is in particular convenient with the self-interference DHM concept. Results from the characterization of the method show that a reduction of coherence induced disturbances up to 70 percent can be achieved. Finally, the performance for enhanced quantitative imaging of living cells is demonstrated. PMID:25574433

Schubert, Robin; Vollmer, Angelika; Ketelhut, Steffi; Kemper, Björn



Compact, low power radio frequency cavity for femtosecond electron microscopy  

SciTech Connect

Reported here is the design, construction, and characterization of a small, power efficient, tunable dielectric filled cavity for the creation of femtosecond electron bunches in an existing electron microscope without the mandatory use of femtosecond lasers. A 3 GHz pillbox cavity operating in the TM{sub 110} mode was specially designed for chopping the beam of a 30 keV scanning electron microscope. The dielectric material used is ZrTiO{sub 4}, chosen for the high relative permittivity ({epsilon}{sub r}= 37 at 10 GHz) and low loss tangent (tan {delta}= 2 x 10{sup -4}). This allows the cavity radius to be reduced by a factor of six, while the power consumption is reduced by an order of magnitude compared to a vacuum pillbox cavity. These features make this cavity ideal as a module for existing electron microscopes, and an alternative to femtosecond laser systems integrated with electron microscopes.

Lassise, A.; Mutsaers, P. H. A.; Luiten, O. J. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)



Localization of fluorescently labeled structures in frozen-hydrated samples using integrated light electron microscopy.  


Correlative light and electron microscopy is an increasingly popular technique to study complex biological systems at various levels of resolution. Fluorescence microscopy can be employed to scan large areas to localize regions of interest which are then analyzed by electron microscopy to obtain morphological and structural information from a selected field of view at nm-scale resolution. Previously, an integrated approach to room temperature correlative microscopy was described. Combined use of light and electron microscopy within one instrument greatly simplifies sample handling, avoids cumbersome experimental overheads, simplifies navigation between the two modalities, and improves the success rate of image correlation. Here, an integrated approach for correlative microscopy under cryogenic conditions is presented. Its advantages over the room temperature approach include safeguarding the native hydrated state of the biological specimen, preservation of the fluorescence signal without risk of quenching due to heavy atom stains, and reduced photo bleaching. The potential of cryo integrated light and electron microscopy is demonstrated for the detection of viable bacteria, the study of in vitro polymerized microtubules, the localization of mitochondria in mouse embryonic fibroblasts, and for a search into virus-induced intracellular membrane modifications within mammalian cells. PMID:23261400

Faas, F G A; Bárcena, M; Agronskaia, A V; Gerritsen, H C; Moscicka, K B; Diebolder, C A; van Driel, L F; Limpens, R W A L; Bos, E; Ravelli, R B G; Koning, R I; Koster, A J



High-Contrast Observation of Unstained Proteins and Viruses by Scanning Electron Microscopy  

PubMed Central

Scanning electron microscopy (SEM) is an important tool for the nanometre-scale analysis of the various samples. Imaging of biological specimens can be difficult for two reasons: (1) Samples must often be left unstained to observe detail of the biological structures; however, lack of staining significantly decreases image contrast. (2) Samples are prone to serious radiation damage from electron beam. Herein we report a novel method for sample preparation involving placement on a new metal-coated insulator film. This method enables obtaining high-contrast images from unstained proteins and viruses by scanning electron microscopy with minimal electron radiation damage. These images are similar to those obtained by transmission electron microscopy. In addition, the method can be easily used to observe specimens of proteins, viruses and other organic samples by using SEM. PMID:23056522

Ogura, Toshihiko



Three-Dimensional Electron Microscopy Simulation with the CASINO Monte Carlo Software  

PubMed Central

Monte Carlo softwares are widely used to understand the capabilities of electron microscopes. To study more realistic applications with complex samples, 3D Monte Carlo softwares are needed. In this paper, the development of the 3D version of CASINO is presented. The software feature a graphical user interface, an efficient (in relation to simulation time and memory use) 3D simulation model, accurate physic models for electron microscopy applications, and it is available freely to the scientific community at this website: It can be used to model backscattered, secondary, and transmitted electron signals as well as absorbed energy. The software features like scan points and shot noise allow the simulation and study of realistic experimental conditions. This software has an improved energy range for scanning electron microscopy and scanning transmission electron microscopy applications. PMID:21769885

Demers, Hendrix; Poirier-Demers, Nicolas; Couture, Alexandre Réal; Joly, Dany; Guilmain, Marc; de Jonge, Niels; Drouin, Dominique



[Significance of histopathologic analysis of skin lesions in scleromyxedema. Light microscopy, electron microscopy, immunohistochemistry and immunofluorescence microscopy].  


Scleromyxedema (SM) may be considered as a possible disease entity in the differential diagnosis of scleroderma. Clinical data and the results of light, immunohistochemical, immunofluorescence and electron microscopic study of skin biopsies taken from a 53-year old patient with SM are reported. In the patient with SM in which abnormal serum paraprotein was not identified, the skin biopsy showed mucinous material in the dermis and proliferation of fibroblasts accompanied by mild dermal sclerosis. Immunofluorescence showed scanty granular IgG along the epidermal basement membrane and IgG and C1q focally along the connective tissue fibres in the dermis of clinically involved skin. In addition to clinical findings, detailed skin biopsy studies including contemporary techniques can contribute to the diagnosis of the disease. PMID:9816405

Krajnc, I; Vizjak, A; Hvala, A; Jurcic, V; Rozman, B



The significance of histologic analysis of skin lesions in porphyria cutanea tarda. Light microscopy, electron microscopy, immunohistochemical and immunofluorescence analysis.  


Porphyria cutanea tarda (PCT) is one of several entities in the differential diagnosis of scleroderma. We report a 62-year-old man with PCT diagnosed since two decades. Clinical data and the results of light microscopy, immunohistochemistry, immunofluorescence and electron microscopy of skin biopsies are presented. The biopsy revealed sclerosis of the dermis mainly due to increased collagens I and III, and accumulation of collagen IV, which had caused the vessel wall to thicken. Immunofluorescence for detection of immune reactants was negative. It was concluded that the histomorphology of PCT of long duration may be similar to that of scleroderma. Nevertheless, in addition to clinical findings, detailed skin biopsy studies including contemporary techniques can contribute to the differentiation of these diseases. PMID:9816639

Krajnc, I; Vizjak, A; Hvala, A; Jurci?, V; Rozman, B



Materials Advances through Aberration-Corrected Electron Microscopy  

SciTech Connect

Over the last few years, the performance of electron microscopes has undergone a dramatic improvement, with achievable resolution having more than doubled. It is now possible to probe individual atomic sites in many materials and to determine atomic and electronic structure with single-atom sensitivity. This revolution has been enabled by the successful correction of the dominant aberrations present in electron lenses. In this review, the authors present a brief overview of these instrumental advances, emphasizing the new insights they provide to several areas of materials research.

Pennycook, Stephen J [ORNL; Varela del Arco, Maria [ORNL; Hetherington, Crispin J. D. [University of Oxford; Kirkland, Angus I. [University of Oxford



Elastin and collagen remodeling in emphysema. A scanning electron microscopy study.  

PubMed Central

The relationship between elastin degradation and emphysema is well known. Recent evidence suggests that a complex process of pulmonary remodeling occurs within the emphysematous lung. The aim of this study was to assess the extent of extracellular matrix remodeling in emphysema by ultrastructural examination of elastin and collagen templates in an animal model of emphysema and in human emphysematous lungs. Emphysema was induced in rats by the intratracheal administration of porcine pancreatic elastase. Human lung samples were obtained at surgical resection for lung carcinoma. Emphysema was confirmed morphometrically and quantitated using the mean linear intercept. Matching sections were treated with sodium hydroxide and formic acid to expose collagen and elastin templates, respectively. Scanning electron microscopy with stereo-pair imaging allowed three-dimensional visualization of the exposed templates. In emphysematous lungs from both sources, sheets of elastin were disrupted and perforated with multiple fenestrations. In elastase-induced emphysema, this disintegration was accompanied by a marked increase in thickness of collagen fibrils, which contrasted with the fine fibrillar network of control lungs. Similarly, a pattern of thickened fibrils and disorganized deposition of collagen was observed in human lungs. In conclusion, these findings support the novel concept of increased collagen deposition and aberrant collagen remodeling in the pathogenesis of emphysema. Images Figure 1 Figure 2 Figure 3 PMID:8863687

Finlay, G. A.; O'Donnell, M. D.; O'Connor, C. M.; Hayes, J. P.; FitzGerald, M. X.



Pre-Clustering of the B Cell Antigen Receptor Demonstrated by Mathematically Extended Electron Microscopy  

PubMed Central

The B cell antigen receptor (BCR) plays a crucial role in adaptive immunity, since antigen-induced signaling by the BCR leads to the activation of the B cell and production of antibodies during an immune response. However, the spatial nano-scale organization of the BCR on the cell surface prior to antigen encounter is still controversial. Here, we fixed murine B cells, stained the BCRs on the cell surface with immuno-gold and visualized the distribution of the gold particles by transmission electron microscopy. Approximately 30% of the gold particles were clustered. However the low staining efficiency of 15% precluded a quantitative conclusion concerning the oligomerization state of the BCRs. To overcome this limitation, we used Monte-Carlo simulations to include or to exclude possible distributions of the BCRs. Our combined experimental-modeling approach assuming the lowest number of different BCR sizes to explain the observed gold distribution suggests that 40% of the surface IgD-BCR was present in dimers and 60% formed large laminar clusters of about 18 receptors. In contrast, a transmembrane mutant of the mIgD molecule only formed IgD-BCR dimers. Our approach complements high resolution fluorescence imaging and clearly demonstrates the existence of pre-formed BCR clusters on resting B cells, questioning the classical cross-linking model of BCR activation. PMID:24367367

Fiala, Gina J.; Kaschek, Daniel; Blumenthal, Britta; Reth, Michael; Timmer, Jens; Schamel, Wolfgang W. A.



Analysis of the phiX DNA replication cycle by electron microscopy.  


We have monitored the development of intracellular phiX DNA forms during the course of a virus life cycle that duplicates as closely as possible the normal infection of individual cells by single virions. The viral DNA was isolated in a one-step purification procedure, and quantitative electron microscopy was performed on the samples, resulting in the following conclusions: (i) Early in the life cycle, when the cells accumulate duplex rings, two types of DNA replication intermediates are observed: a rolling circle with a single-stranded tail; and a novel form, a single-stranded circle that is partially duplex. Thus, duplex ring synthesis appears to occur in two asymmetric steps, with positive strand DNA first being processed from the tail of the rolling circle and circularized, before it acts as a template for negative strand synthesis. (ii) Late in the life cycle, as single-stranded circles are synthesized and virus particles are assembled, only one replicating intermediate is observed--the rolling circle with a single-stranded tail. At this stage, the number of rolling circles reaches a level of about 35 per cell. (iii) The net rate of polymerization in the rolling circle intermediates is about 200 nucleotides per sec. PMID:273222

Koths, K; Dressler, D



Electron microscopy and microanalysis of steel weld joints after long time exposures at high temperatures  

NASA Astrophysics Data System (ADS)

The structural changes of three trial weld joints of creep resistant modified 9Cr-1Mo steels and low alloyed chromium steel after post-weld heat treatment and long-term creep tests were investigated. Smooth cross-weld specimens ruptured in different zones of the weld joints as a result of different structural changes taking place during creep exposures. The microstructure of the weld joint is heterogeneous and consequently microstructural development can be different in the weld metal, the heat affected zone, and the base material. Precipitation reactions, nucleation and growth of some particles and dissolution of others, affect the strengthening of the matrix, recovery at high temperatures, and the resulting creep resistance. Therefore, a detailed study of secondary phase's development in individual zones of weld joints can elucidate mechanism of cracks propagation in specific regions and the causes of creep failure. Type I and II fractures in the weld metal and Type IV fractures in the fine prior austenite grain heat affected zones occurred after creep tests at temperatures ranging from 525 to 625 °C and under stresses from 40 to 240 MPa. An extended metallographic study of the weld joints was carried out using scanning and transmission electron microscopy, energy-dispersive and wave-dispersive X-ray microanalysis. Carbon extraction replicas and thin foils were prepared from individual weld joint regions and quantitative evaluation of dislocation substructure and particles of secondary phases has been performed.

Jandová, D.; Kasl, J.; Rek, A.



Developing a denoising filter for electron microscopy and tomography data in the cloud  

PubMed Central

The low radiation conditions and the predominantly phase-object image formation of cryo-electron microscopy (cryo-EM) result in extremely high noise levels and low contrast in the recorded micrographs. The process of single particle or tomographic 3D reconstruction does not completely eliminate this noise and is even capable of introducing new sources of noise during alignment or when correcting for instrument parameters. The recently developed Digital Paths Supervised Variance (DPSV) denoising filter uses local variance information to control regional noise in a robust and adaptive manner. The performance of the DPSV filter was evaluated in this review qualitatively and quantitatively using simulated and experimental data from cryo-EM and tomography in two and three dimensions. We also assessed the benefit of filtering experimental reconstructions for visualization purposes and for enhancing the accuracy of feature detection. The DPSV filter eliminates high-frequency noise artifacts (density gaps), which would normally preclude the accurate segmentation of tomography reconstructions or the detection of alpha-helices in single-particle reconstructions. This collaborative software development project was carried out entirely by virtual interactions among the authors using publicly available development and file sharing tools. PMID:23066432

Starosolski, Zbigniew; Szczepanski, Marek; Wahle, Manuel; Rusu, Mirabela




EPA Science Inventory

A semi-quantitative scanning electron microscope (SEK) analytical technique has been developed to examine granular activated carbon (GAC) utilized as media for biomass attachment in liquid waste treatment (combined processes). he procedure allows for the objective monitoring, com...


Pulmonary mineral dust. A study of ninety patients by electron microscopy, electron microanalysis, and electron microdiffraction.  

PubMed Central

The results of a study of 90 patients are presented. Intrapulmonary mineral deposits were characterized by electron diffraction and electron probe microanalysis. Using this method, pneumoconioses may be distinguidhed from other pneumopathies. In cases of pneumoconiosis, there exists a specific relationship between the etiology of the dust exposure and the crystallographic characteristics of the intrapulmonary deposits. The nature of the deposits may be indicative of a specific type of pneumoconiosis. This method is particularly useful in differentiating between asbestos bodies and ferruginous bodies. The value of the method in general and its importance in the study of pneumoconiosis are discussed. Images Figure 4 Figure 13 Figure 5 Figure 14 Figure 6 Figure 15 Figure 7 Figure 16 Figure 8 Figure 17 Figure 1 Figure 9 Figure 10 Figure 2 Figure 11 Figure 3 Figure 12 PMID:937507

Berry, J. P.; Henoc, P.; Galle, P.; Pariente, R.




PubMed Central

Isolated rat liver mitochondria were incubated in vitro under conditions supporting the massive accumulation of calcium and phosphate. Samples were embedded, thin sectioned, and examined in the electron microscope. The intramitochondrial distribution of insoluble or structure-bound mineral substances was studied by electron microscopy coupled with recently developed techniques of high resolution microincineration. As shown previously, the ion-loaded mitochondria acquire large, internal granules which have inherent electron opacity indicative of high mineral content. Study of ash patterns in preselected areas of sections directly confirmed the high mineral content of the granules, and the appearance of the residues was consistent with the copresence in the granules of some organic material. Other mitochondrial structures were almost devoid of mineral. Thin sections of unincubated control mitochondria also were incinerated. They were found to contain appreciable amounts of intrinsic mineral, seemingly associated with membranes. The normal, dense matrix granules commonly seen in unaltered mitochondria could be seen in intact sections of these control preparations, but after burning no definite correspondence of any ash to the granules could be demonstrated. The normal granules perhaps do not contain mineral. Heating experiments on ash patterns of all the preparations demonstrated the thermal stability and crystallizability of the ash. The crystallized ash of the in vitro-produced dense granules was tentatively shown by electron diffraction to be ?-tricalcium phosphate (whitlockite). This, together with evidence from the literature, suggests that the original, noncrystalline mineral may be a colloidal, subcrystalline precursor of calcium-deficient hydroxyapatite. Experiments were performed on synthetic calcium phosphates for comparison. Other possible applications of the microincineration techniques are briefly discussed. PMID:4878171

Thomas, Richard S.; Greenawalt, John W.



Type of presentation: Oral IT-10-O-2435 Towards 4-D EEL spectroscopic scanning confocal electron microscopy  

E-print Network

Type of presentation: Oral IT-10-O-2435 Towards 4-D EEL spectroscopic scanning confocal electron microscopy (SCEM-EELS) optical sectioning on a Cc and Cs double-corrected transmission electron microscope electron microscopy with electron energy-loss spectroscopy (STEM-EELS) has been widely used for materials

Dunin-Borkowski, Rafal E.


Inner-Shell Excitation Spectroscopy and X-ray Photoemission Electron Microscopy of Adhesion Promoters  

E-print Network

Inner-Shell Excitation Spectroscopy and X-ray Photoemission Electron Microscopy of Adhesion, and AdVanced Electronic Materials, The Dow Chemical Company, 1712 Building, Midland, Michigan 48674 ReceiVed: January 11, 2005 The C 1s, Si 2p,