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Sample records for tem microscopy

  1. Cryogenic transmission electron microscopy (cryo-TEM) for studying the morphology of colloidal drug delivery systems

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Horst, Jennifer C; Bunjes, Heike

    2011-01-01

    Cryogenic transmission electron microscopy (cryo-TEM) has evolved into an indispensable tool for the characterization of colloidal drug delivery systems. It can be applied to study the size, shape and internal structure of nanoparticulate carrier systems as well as the overall colloidal composition...... of the corresponding dispersions. This review gives a short overview over the instrumentation used in cryo-TEM experiments and over the sample preparation procedure. Selected examples of cryo-TEM studies on colloidal drug carrier systems, including liposomes, colloidal lipid emulsions, solid lipid nanoparticles...

  2. Atom-counting in High Resolution Electron Microscopy:TEM or STEM - That's the question.

    Science.gov (United States)

    Gonnissen, J; De Backer, A; den Dekker, A J; Sijbers, J; Van Aert, S

    2017-03-01

    In this work, a recently developed quantitative approach based on the principles of detection theory is used in order to determine the possibilities and limitations of High Resolution Scanning Transmission Electron Microscopy (HR STEM) and HR TEM for atom-counting. So far, HR STEM has been shown to be an appropriate imaging mode to count the number of atoms in a projected atomic column. Recently, it has been demonstrated that HR TEM, when using negative spherical aberration imaging, is suitable for atom-counting as well. The capabilities of both imaging techniques are investigated and compared using the probability of error as a criterion. It is shown that for the same incoming electron dose, HR STEM outperforms HR TEM under common practice standards, i.e. when the decision is based on the probability function of the peak intensities in HR TEM and of the scattering cross-sections in HR STEM. If the atom-counting decision is based on the joint probability function of the image pixel values, the dependence of all image pixel intensities as a function of thickness should be known accurately. Under this assumption, the probability of error may decrease significantly for atom-counting in HR TEM and may, in theory, become lower as compared to HR STEM under the predicted optimal experimental settings. However, the commonly used standard for atom-counting in HR STEM leads to a high performance and has been shown to work in practice. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. eV-TEM: Transmission electron microscopy in a low energy cathode lens instrument

    Energy Technology Data Exchange (ETDEWEB)

    Geelen, Daniël, E-mail: geelen@physics.leidenuniv.nl [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Thete, Aniket [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Schaff, Oliver; Kaiser, Alexander [SPECS GmbH, Voltastrasse 5, D-13355 Berlin (Germany); Molen, Sense Jan van der [Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, P.O. Box 9504, 2300 RA Leiden (Netherlands); Tromp, Rudolf [IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, NY 10598 (United States)

    2015-12-15

    We are developing a transmission electron microscope that operates at extremely low electron energies, 0–40 eV. We call this technique eV-TEM. Its feasibility is based on the fact that at very low electron energies the number of energy loss pathways decreases. Hence, the electron inelastic mean free path increases dramatically. eV-TEM will enable us to study elastic and inelastic interactions of electrons with thin samples. With the recent development of aberration correction in cathode lens instruments, a spatial resolution of a few nm appears within range, even for these very low electron energies. Such resolution will be highly relevant to study biological samples such as proteins and cell membranes. The low electron energies minimize adverse effects due to radiation damage. - Highlights: • We present a new way of performing low energy transmission electron microscopy in an aberration corrected LEEM/PEEM instrument. • We show a proof of principle where we measure transmitted electrons through a suspended graphene monolayer with a preliminary setup. • We present an improved setup design that provides better control of the incident electron beam.

  4. Transmission Electron Microscopy (TEM Through Focused ION Beam (FIB from Vitrified Chromium Wastes

    Directory of Open Access Journals (Sweden)

    S. Ballesteros-Elizondo

    2011-08-01

    Full Text Available This study shows how the Focused Ion Beam (FIB has been applied to vitrified materials obtained from chromiumwastes. Due to the issues arising during conventional Ar+ ion milling, it was necessary to thin these samples usingFIB. Difficulties came from the heterogeneous size between chromium spinels and the residual glass phase. The FIBwas applied to obtain thin foils from vitrified materials. These brittle and heterogeneous samples result in specimenswith many perforations and chipping when using conventional thinning below 100 nanometers. Alternatively, FIBallowed thinning in the range of 60 - 80 nanometers from specifically selected areas such as the areas containingspinel crystals Mg(Al,Cr2O4 in order to facilitate the final Transmission Electron Microscopy (TEM observations. Inthis paper, FIB is shown to be a very powerful microtool as a brittle samples preparation method as well as providingan alternative way for performing conventional ceramography and Ar+ ion milling. FIB is a much less destructivemethod with greater observed capacity in the quantity and analysis of microcrystalline phases.

  5. Novel critical point drying (CPD) based preparation and transmission electron microscopy (TEM) imaging of protein specific molecularly imprinted polymers (HydroMIPs)

    OpenAIRE

    Hawkins, DM; Ellis, EA; Stevenson, D.; Holzenburg, A; Reddy, Subrayal M.

    2007-01-01

    We report the transmission electron microscopy (TEM) imaging of a hydrogel-based molecularly imprinted polymer (HydroMIP) specific to the template molecule bovine haemoglobin (BHb). A novel critical point drying based sample preparation technique was employed to prepare the molecularly imprinted polymer (MIP) samples in a manner that would facilitate the use of TEM to image the imprinted cavities, and provide an appropriate degree of both magnification and resolution to image polymer architec...

  6. First ultrastructural data on the human tapeworm Taenia asiatica eggs by scanning and transmission electron microscopy (SEM, TEM).

    Science.gov (United States)

    Galán-Puchades, M Teresa; Yang, Yichao; Marcilla, Antonio; Choe, Seongjun; Park, Hansol; Osuna, Antonio; Eom, Keeseon S

    2016-09-01

    Humans are definitive hosts of three species of the Taenia genus, namely Taenia solium, Taenia saginata and Taenia asiatica. The relative novelty of the latter explains the lack of knowledge concerning certain relevant aspects related to this parasite, such as its definite geographical distribution and whether its eggs can infect humans or not. So far, only the eggs of T. solium are known to be infective for humans, producing cysticercosis. Although eggs contain the infective stage, the oncosphere, there is a lack of research on the ultrastructure of eggs of human taeniids. We show, for the first time, the ultrastructure of eggs of T. asiatica by means of SEM and TEM analyses. We detected all the envelopes, namely the egg shell, vitelline layer, outer embryophoric membrane, embryophore, granular layer, basal membrane, oncospheral membrane and oncospheral tegument. Hooks surrounded by myofibrils and glycogen-like particles, the two types of secretory granules of the penetration glands, as well as several nuclei and mitochondria were also revealed in the oncospheres. In addition to the already known structures in eggs from other Taenia species, the presence of two types of small vesicles is described herein, possibly corresponding to exosomes and ectosomes because of their shape and size, which could participate in the host/parasite intercellular communication.

  7. Nanoscale intracellular mass-density alteration as a signature of the effect of alcohol on early carcinogenesis: A transmission electron microscopy (TEM) study

    CERN Document Server

    Ghimire, Hemendra M; Sahay, Peeyush; Almabadi, Huda; Tripathi, Vibha; Skalli, Omar; Rao, R K; Pradhan, Prabhakar

    2015-01-01

    Alcohol consumption interferes with the functioning of multiple organ systems, causing changes in the chemistry, physiology and pathology of tissues and cellular organelles. Although epigenetic modifications underlie the development of cancer, exposure to carcinogenic chemicals, such as alcohol, can also contribute to disease development. However, the effects of chronic alcoholism on normal or pre-carcinogenic cells/tissues in different organelles are not well understood. Therefore, we herein study the effect of alcohol consumption on colonic nucleus using control and azoxymethane (AOM) and dextran sulfate sodium (DSS) treated carcinogenic mice. Previous studies showed that progression of carcinogenesis is associated with increase in the degree of intranuclear nanoscale structural disorder. In the present work, we quantify the degree of nanostructural disorder as a measure of carcinogenesis. To accomplish this, transmission electron microscopy (TEM) imaging of respective colonic epithelial cell nuclei are use...

  8. Transmission Electron Microscopy (TEM) Observations of Female Oocytes From Nilaparvata lugens (Hemiptera: Delphacidae): Antibiotic Jinggangmycin (JGM)-Induced Stimulation of Reproduction and Associated Changes in Hormone Levels.

    Science.gov (United States)

    Xu, Bing; You, Lin-Lin; Wu, You; Ding, Jun; Ge, Lin-Quan; Wu, Jin-Cai

    2016-08-01

    Previous studies have demonstrated that the agricultural antibiotic jinggangmycin (JGM) stimulates reproduction in the brown planthopper Nilaparvata lugens Stål and that the stimulation of brown planthopper reproduction induced by JGM is regulated by the fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) genes. However, a key issue in the stimulation of reproduction induced by pesticides involves the growth and development of oocytes. Therefore, the present study investigated oocyte changes via transmission electron microscopy (TEM) and changes in hormone levels (juvenile hormones (JH) and 20-hydroxyecdysone (20 E)) in JGM-treated females. TEM observations showed that the size of the lipid droplets in the oocytes of JGM-treated females, compared with those in the oocytes of the control females, significantly reduced by 32.6 and 29.8% at 1 and 2 d after emergence (1 and 2 DAE), respectively. In addition, the JH levels of JGM-treated females at 1 and 2 DAE were increased by 49.7 and 45.7%, respectively, whereas 20 E levels decreased by 36.0 and 30.0%, respectively. We conclude that JGM treatments lead to substantial changes in lipid metabolism, which are directly and indirectly related to stimulation of reproduction of brown planthopper together with our previous findings. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

  9. Bioaccumulation and localization of exogenous cadmium in a teleost by electron microscopy (TEM) and its specific quantitation by electron probe X-ray microanalysis (EPMA).

    Science.gov (United States)

    Tayal, A K; Kaur, I; Mathur, R P

    2000-03-01

    A cadmium bioconcentration study was carried out in a fresh water teleost, Colisa fasciatus, to study the bioaccumulation kinetics and fate of exogenous cadmium (Cd) in biological tissues. Study shows that on exposure of the fish to a sublethal concentration of cadmium in test water, Cd uptake results in its bioconcentration in gills, liver and muscle tissues. To explore whether the accumulated Cd reaches the membranes or inside the cells, transmission electron microscopy (TEM) of the thin sections of tissues was done after histochemical localization of Cd in cells by modified SST method. TEM studies of sections of gills, liver and muscle tissues showed the deposits of exogenous Cd (visualized as dense clouds) in biological cells. This suggests the presence of free or loosely bound Cd on the membranes and inside the cells, which in the presence of Na2S is converted into insoluble metal sulfides. Electron probe X-ray microanalysis (EPMA) studies confirmed the presence of Cd on the membrane surface as well as inside the cells of bioindicator organs suggesting involvement of membrane transport of exogenous Cd inside the cells and its deposition as loosely bound insoluble metal complexes.

  10. Microscopy

    Science.gov (United States)

    Patricia A. Moss; Les Groom

    2001-01-01

    Microscopy is the study and interpretation of images produced by a microscope. "Interpretation" is the keyword, because the microscope enables one to see structures that are too small or too close together to be resolved by the unaided eye. (The human eye cannot separate two points or lines that are closer together than 0.1 mm.) it is important to...

  11. TEM Video Compressive Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, Andrew; Kovarik, Libor; Abellan, Patricia; Yuan, Xin; Carin, Lawrence; Browning, Nigel D.

    2015-08-01

    One of the main limitations of imaging at high spatial and temporal resolution during in-situ TEM experiments is the frame rate of the camera being used to image the dynamic process. While the recent development of direct detectors has provided the hardware to achieve frame rates approaching 0.1ms, the cameras are expensive and must replace existing detectors. In this paper, we examine the use of coded aperture compressive sensing methods [1, 2, 3, 4] to increase the framerate of any camera with simple, low-cost hardware modifications. The coded aperture approach allows multiple sub-frames to be coded and integrated into a single camera frame during the acquisition process, and then extracted upon readout using statistical compressive sensing inversion. Our simulations show that it should be possible to increase the speed of any camera by at least an order of magnitude. Compressive Sensing (CS) combines sensing and compression in one operation, and thus provides an approach that could further improve the temporal resolution while correspondingly reducing the electron dose rate. Because the signal is measured in a compressive manner, fewer total measurements are required. When applied to TEM video capture, compressive imaging couled improve acquisition speed and reduce the electron dose rate. CS is a recent concept, and has come to the forefront due the seminal work of Candès [5]. Since the publication of Candès, there has been enormous growth in the application of CS and development of CS variants. For electron microscopy applications, the concept of CS has also been recently applied to electron tomography [6], and reduction of electron dose in scanning transmission electron microscopy (STEM) imaging [7]. To demonstrate the applicability of coded aperture CS video reconstruction for atomic level imaging, we simulate compressive sensing on observations of Pd nanoparticles and Ag nanoparticles during exposure to high temperatures and other environmental conditions

  12. Confocal microscopy

    Indian Academy of Sciences (India)

    molecular aggregates in artificial light harvesting sys- tem it is important to elucidate the exciton dynamics of individual micro-rods which can be achieved by using confocal microscopy and polarization resolved single molecule fluorescence spectroscopy.30 41 In the present work, we have studied exciton dynamics of two.

  13. Appendix B: Summary of TEM Particle Size Distribution Datasets

    Science.gov (United States)

    As discussed in the main text (see Section 5.3.2), calculation of the concentration of asbestos fibers in each of the bins of potential interest requires particle size distribution data derived using transmission electron microscopy (TEM).

  14. In-situ TEM Studies : Heat-treatment and Corrosion

    NARCIS (Netherlands)

    Malladi, S.R.K.

    2014-01-01

    Transmission electron microscopy (TEM) has been well known as a powerful characterisation tool to understand the structure and composition of various materials down to the atomic level. Over the years, several TEM studies have been carried out to understand the compositional, structural and

  15. Nanoparticle embedded chitosan film for agglomeration free TEM images.

    Science.gov (United States)

    Dogan, Üzeyir; Çiftçi, Hakan; Cetin, Demet; Suludere, Zekiye; Tamer, Ugur

    2017-02-01

    Transmission electron microscopy (TEM) is a very useful and commonly used microscopy technique, used especially for the characterization of nanoparticles. However, the identification of the magnetic nanoparticle could be thought problematic in TEM analysis, due to the fact that the magnetic nanoparticles are usually form aggregates on the TEM grid to form bigger particles generating higher stability. This prevents to see exact shape and size of each nanoparticle. In order to overcome this problem, a simple process for the formation of well-dispersed nanoparticles was conducted, by covering chitosan film on the unmodified copper grid, it was said to result in aggregation-free TEM images. It is also important to fix the magnetic nanoparticles on the TEM grids, due to possible contamination of TEM filament which is operated under high vacuum conditions. The chitosan film matrix also helps to protect the TEM filament from contact with magnetic nanoparticles during the imaging process. The proposed procedure offers a quick method to fix the nanoparticles in a conventional copper TEM grid and chitosan matrix prevents agglomeration of nanoparticles, and thus getting TEM images showing well-dispersed individual nanoparticles. © 2016 Wiley Periodicals, Inc.

  16. Quantification of small, convex particles by TEM

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Sigmund J. [SINTEF Materials and Chemistry, Department of Synthesis and Properties, Material Physics, NO-7465 Trondheim (Norway)], E-mail: sigmund.j.andersen@sintef.no; Holme, Borge [SINTEF Materials and Chemistry, P.O. Box 124, Blindern, NO-0314 Oslo (Norway); Marioara, Calin D. [SINTEF Materials and Chemistry, Department of Synthesis and Properties, Material Physics, NO-7465 Trondheim (Norway)

    2008-07-15

    It is shown how size distributions of arbitrarily oriented, convex, non-overlapping particles extracted from conventional transmission electron microscopy (TEM) images may be determined by a variation of the Schwartz-Saltykov method. In TEM, particles cut at the surfaces have diminished projections, which alter the observed size distribution. We represent this distribution as a vector and multiply it with the inverse of a matrix comprising thickness-dependent Scheil or Schwartz-Saltykov terms. The result is a corrected size distribution of the projections of uncut particles. It is shown how the real (3D) distribution may be estimated when particle shape is considered. Computer code to generate the matrix is given. A log-normal distribution of spheres and a real distribution of pill-box-shaped dispersoids in an Al-Mg-Si alloy are given as examples. The errors are discussed in detail.

  17. In Situ TEM Creation of Nanowire Devices

    DEFF Research Database (Denmark)

    Alam, Sardar Bilal

    Integration of silicon nanowires (SiNWs) as active components in devices requires that desired mechanical, thermal and electrical interfaces can be established between the nanoscale geometry of the SiNW and the microscale architecture of the device. In situ transmission electron microscopy (TEM...... of SiNW were also investigated in situ. SiNWs were grown on silicon microcantilever heaters using the VLS mechanism. When grown across a gap between adjacent cantilevers, contact was formed when the SiNW impinged on the sidewall of an adjacent cantilever. Using in situ TEM, SiNW contact formation...... process at high temperatures was observed in real time. As the eutectic droplet made contact, it wetted the surface; Si growth catalyzed by the eutectic continued, while at the same time Au often migrated/diffused away from the contact site. The parameters of this contact formation process were measured...

  18. TEM turbulence optimisation in stellarators

    CERN Document Server

    Proll, J H E; Xanthopoulos, P; Lazerson, S A; Faber, B J

    2015-01-01

    With the advent of neoclassically optimised stellarators, optimising stellarators for turbulent transport is an important next step. The reduction of ion-temperature-gradient-driven turbulence has been achieved via shaping of the magnetic field, and the reduction of trapped-electron mode (TEM) turbulence is adressed in the present paper. Recent analytical and numerical findings suggest TEMs are stabilised when a large fraction of trapped particles experiences favourable bounce-averaged curvature. This is the case for example in Wendelstein 7-X [C.D. Beidler $\\textit{et al}$ Fusion Technology $\\bf{17}$, 148 (1990)] and other Helias-type stellarators. Using this knowledge, a proxy function was designed to estimate the TEM dynamics, allowing optimal configurations for TEM stability to be determined with the STELLOPT [D.A. Spong $\\textit{et al}$ Nucl. Fusion $\\bf{41}$, 711 (2001)] code without extensive turbulence simulations. A first proof-of-principle optimised equilibrium stemming from the TEM-dominated stella...

  19. Design, fabrication, and applications of in situ fluid cell TEM.

    Science.gov (United States)

    Li, Dongsheng; Nielsen, Michael H; De Yoreo, James J

    2013-01-01

    In situ fluid cell TEM is a powerful new tool for understanding dynamic processes during liquid phase chemical reactions, including mineral formation. This technique, which operates in the high vacuum of a TEM chamber, provides information on crystal structure, phase, morphology, size, aggregation/segregation, and crystal growth mechanisms in real time. In situ TEM records both crystal structure and morphology at spatial resolutions down to the atomic level with high temporal resolution of up to 10(-6)s per image, giving it distinct advantages over other in situ techniques such as optical microscopy, AFM, or X-ray scattering or diffraction. This chapter addresses the design, fabrication, and assembly of TEM fluid cells and applications of fluid cell TEM to understanding mechanisms of mineralization. © 2013 Elsevier Inc. All rights reserved.

  20. In Situ TEM Electrical Measurements

    DEFF Research Database (Denmark)

    Canepa, Silvia; Alam, Sardar Bilal; Ngo, Duc-The

    2016-01-01

    and measurement of the specimen. Recognizing the benefits of electrical measurements for in situ TEM, many research groups have focused their effort in this field and some of these methods have transferred to ETEM. This chapter will describe recent advances in the in situ TEM investigation of nanostructured...... materials and devices with the specimen being contacted by electrical, mechanical or other means, with emphasis on in situ electrical measurements performed in a gaseous or liquid environment. We will describe the challenges and prospects of electrical characterization of devices and processes induced...... by a voltage in gas and liquids. We will also provide a historical perspective of in situ TEM electrical measurements and applications using electrical contacts....

  1. TEM specimen preparation of a phase-change optical disk

    Science.gov (United States)

    Kouzaki

    2000-01-01

    It has been popular to use transmission electron microscopy (TEM) observation for investigating the microstructure of a phase-change optical disk. In the present work, a new method to prepare a plan-view TEM sample from a disk has been developed. In this method, a copper mesh is placed on a specific area of interest in the disk in advance and then the material is thinned down. By employing this procedure, it becomes possible for the first time to obtain foils that contain the specific area. Furthermore, an advanced method to prepare a cross-sectional TEM sample has also been developed, in which elimination of the polymer substrate is followed by ion milling. With this method, it is possible to prepare cross-sectional foils for high-resolution and analytical electron microscopy observations.

  2. TEM PSHA2015 Reliability Assessment

    Science.gov (United States)

    Lee, Y.; Wang, Y. J.; Chan, C. H.; Ma, K. F.

    2016-12-01

    The Taiwan Earthquake Model (TEM) developed a new probabilistic seismic hazard analysis (PSHA) for determining the probability of exceedance (PoE) of ground motion over a specified period in Taiwan. To investigate the adequacy of the seismic source parameters adopted in the 2015 PSHA of the TEM (TEM PSHA2015), we conducted several tests of the seismic source models. The observed maximal peak ground acceleration (PGA) of the ML > 4.0 mainshocks in the 23-year data period of 1993-2015 were used to test the predicted PGA of PSHA from the areal and subduction zone sources with the time-independent Poisson assumption. This comparison excluded the observations from 1999 Chi-Chi earthquake, as this was the only earthquake associated with the identified active fault in this past 23 years. We used tornado diagrams to analyze the sensitivities of these source parameters to the ground motion values of the PSHA. This study showed that the predicted PGA for a 63% PoE in the 23-year period corresponded to the empirical PGA and the predicted numbers of PGA exceedances to a threshold value 0.1g close to the observed numbers, confirming the parameter applicability for the areal and subduction zone sources. We adopted the disaggregation analysis from a hazard map to determine the contribution of the individual seismic sources to hazard for six metropolitan cities in Taiwan. The sensitivity tests of the seismogenic structure parameters indicated that the slip rate and maximum magnitude are dominant factors for the TEM PSHA2015. For densely populated faults in SW Taiwan, maximum magnitude is more sensitive than the slip rate, giving the concern on the possible multiple fault segments rupture with larger magnitude in this area, which was not yet considered in TEM PSHA2015. The source category disaggregation also suggested that special attention is necessary for subduction zone earthquakes for long-period shaking seismic hazards in Northern Taiwan.

  3. Environmental TEM in an Aberration Corrected Microscope

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    the microscope column. The effects of gas on the electron wave in the objective lens are not well understood and needs further attention. Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast, provides a means for understanding......The increasing use of environmental transmission electron microscopy (ETEM) in materials science provides exciting new possibilities for investigating chemical reactions and understanding both the interaction of fast electrons with gas molecules and the effect of the presence of gas on high......‐resolution imaging. A gaseous atmosphere in the pole‐piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 10‐20 nm), the gas in the environmental...

  4. Environmental TEM in Materials Research

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    Over the last decades, electron microscopy has played a large role in materials research. The increasing use of particularly environmental transmission electron microscopy (ETEM) in materials science provides new possibilities for investigating nanoscale components at work. Careful experimentation....... Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast provides a means for understanding the issues involved with imaging in the presence of a gas. In this work, capabilities, possibilities and challenges of using ETEM...

  5. Environmental TEM for Materials Research

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum

    Over the last decades, electron microscopy has played a large role in materials research. The increasing use of particularly environmental transmission electron microscopy (ETEM) in materials science provides new possibilities for investigating nanoscale components at work. Careful experimentation...... not spatially localized. Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast provides a means for understanding the issues involved with imaging in the presence of a gas.In this work, capabilities, possibilities and challenges...

  6. A TEM Study on the Ti-Alloyed Grey Iron

    DEFF Research Database (Denmark)

    Moumeni, Elham; Tiedje, Niels Skat; Grumsen, Flemming Bjerg

    2014-01-01

    The microstructure of graphite flakes in titanium alloyed cast iron is studied using electron microscopy techniques. Dual beam SEM/FIB has been used for TEM sample preparation. A TEM study has been carried out on graphite flakes in grey cast iron using selected area electron diffraction. Based...... and that there is a high proportion of twins in the fine grained graphite. It appears that twinning and stacking faults are involved in the fine grained structure of the graphite. It is discussed how Ti addition affect crystal growth and may lead to formation of superfine graphite....

  7. Microfabricated Nanofluidic cells for in situ liquid TEM

    DEFF Research Database (Denmark)

    Laganà, Simone

    structural information of materials. In this regard, in situ liquid cell electron microscopy (EM) is one of the new emerging methods that gained a lot of attention by making possible to observe processes and samples in liquid environments within the chamber of an electron microscope. The main focus...... on wafer bonding of Atomic layer deposited (ALD) Al2O3 on Si3N4 membranes. With the improved liquid layer thickness control, we use the devices to measure the electron mean free path in water which is a fundamental aspect of TEM studies, and present the high-resolution TEM capabilities of the nanofluidic...

  8. Illuminating Electron Microscopy of Photocatalysts

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    energy into chemical bonds. By means of Transmission Electron Microscopy (TEM) it is possible to gain insight in the fundamentals of their reaction mechanisms, chemical behaviour, structure and morphology before, during and after reaction using in situ investigations. In particular, the environmental TEM...... (ETEM) is the instrument of choice employed in this thesis to perform such studies. Typically, photocatalysts work in gaseous or liquid atmosphere upon light illumination. We aim at reproducing their working conditions in situ. The ETEM allows exposing specimens to a controlled gas atmosphere, thus...... the microscope that allows electron microscopy under nonconventional TEM conditions and new kinds of in situ spectroscopy....

  9. Nanopipes in GaN : Photo-etching and TEM study

    NARCIS (Netherlands)

    Lazar, S.; Weyher, J.L.; Macht, L.; Tichelaar, F.D.; Zandbergen, H.W.

    2004-01-01

    Photochemical (PEC) etching and transmission electron microscopy (TEM) have been used to study the defects in hetero-epitaxial GaN layers. TEM proved that PEC etching reveals not only dislocations but also nanopipes in the form of protruding, whisker-like etch features. It is shown by diffraction

  10. Nanopipes in GaN: photo-etching and TEM study

    NARCIS (Netherlands)

    Lazar, S.; Weyher, J.L.; Macht, L.J.; Tichelaar, F.D.; Zandbergen, H.W.

    2004-01-01

    Photochemical (PEC) etching and transmission electron microscopy (TEM) have been used to study the defects in hetero-epitaxial GaN layers. TEM proved that PEC etching reveals not only dislocations but also nanopipes in the form of protruding, whisker-like etch features. It is shown by diffraction

  11. Direct electron detection in transmission electron microscopy

    OpenAIRE

    Jin, Liang

    2009-01-01

    Since the first prototype of a transmission electron microscope was built in 1931 by Ernst Ruska and Max Knoll, Transmission Electron Microscopy (TEM) has proved to be an essential imaging tool for physicists, material scientists, and biologists. To record the TEM images for analysis, electron microscopists have used specialized electron micrograph film for a long time, until the new developments in TEM, such as electron tomography and cryo- electron microscopy, pushed for the needs of digita...

  12. Suspended DNA structural characterization by TEM diffraction

    KAUST Repository

    Marini, Monica

    2017-12-01

    In this work, micro-fabrication, super-hydrophobic properties and a physiologically compatible preparation step are combined and tailored to obtain background free biological samples to be investigated by Transmission Electron Microscopy (TEM) diffraction technique. The validation was performed evaluating a well-known parameter such as the DNA interbases value. The diffraction spacing measured is in good agreement with those obtained by HRTEM direct metrology and by traditional X-Ray diffraction. This approach addresses single molecule studies in a simplified and reproducible straightforward way with respect to more conventional and widely used techniques. In addition, it overcomes the need of long and elaborated samples preparations: the sample is in its physiological environment and the HRTEM data acquisition occurs without any background interference, coating, staining or additional manipulation. The congruence in the results reported in this paper makes the application of this approach extremely promising towards those molecules for which crystallization remains a hurdle, such as cell membrane proteins and fibrillar proteins.

  13. The Italian reference site for TEM methods

    Directory of Open Access Journals (Sweden)

    Vincenzo Sapia

    2015-11-01

    Full Text Available The success of a long term transient electromagnetic survey (TEM rigorously calls for appropriate system calibration, in addition to advanced processing and inversion of the measured data. In fact, acquisition of TEM data can be affected by a variety of noise sources from both inside and outside the system, making it difficult, for example, to define an absolute turn off time and/or to synchronize transmitter and receiver. For these reasons, a reference site plays an important role. As first step, we performed the calibration of a Geonics 47 at the Lyngby reference site in Denmark. We then set up a new reference site using the same calibrated TEM instrument. The reference site was established in the San Rossore park area (Pisa, where we identified an area that matches the required conditions. Subsequently, a series of TEM measurements were collected in the selected area using two pre-calibrated TEM instruments: the Geonics 47 and the WalkTEM respectively. The reference responses were therefore jointly inverted, obtaining a 5 layers model that was appointed to be the TEM reference model for the site. Afterwards, based on that reference model, we calibrated the Geonics 47 and 57 instruments for a 100 x 100 m central loop configuration. A unique time-shift and a data level shift factor was calculated and applied to the TEM system as result of the calibration procedure. The San Rossore TEM reference site is now available for anyone interested in calibrating TEM systems.

  14. An electron microscopy appraisal of tensile fracture in metallic glasses

    NARCIS (Netherlands)

    Matthews, D. T. A.; Ocelik, V.; Bronsveld, P. M.; De Hosson, J. Th. M.

    Three glass-forming alloy compositions were chosen for ribbon production and subsequent electron microscopy studies. In situ tensile testing with transmission electron microscopy (TEM), followed by ex situ TEM and ex situ scanning electron microscopy (SEM), allowed the deformation processes in

  15. TEM and SEM studies of microstructural transformations of thin iron films during annealing

    NARCIS (Netherlands)

    Lisowski, W.F.; Keim, Enrico G.; Smithers, Mark A.; Smithers, M.A.

    2002-01-01

    High-temperature induced transformations of the bulk structure as well as the surface and bulk morphology of thin polycrystalline iron films have been investigated using a combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The polycrystalline Fe films were

  16. Complete Tem-Tomography: 3D Structure of Gems Cluster

    Science.gov (United States)

    Matsuno, J.; Miyake, A.; Tsuchiyama, A.; Messenger, S.; Nakamura-Messenger, K.

    2015-01-01

    GEMS (glass with embedded metal and sulfide) grains in interplanetary dust particles (IDPs) are considered to be one of the ubiquitous and fundamental building blocks of solids in the Solar System. They have been considered to be interstellar silicate dust that survived various metamorphism or alteration processes in the protoplanetary disk but the elemental and isotopic composition measurements suggest that most of them have been formed in the protoplanetary disk as condensates from high temperature gas. This formation model is also supported by the formation of GEMS-like grains with respect to the size, mineral assemblage, texture and infrared spectrum by condensation experiments from mean GEMS composition materials. Previous GEMS studies were performed only with 2D observation by transmission electron microscopy (TEM) or scanning TEM (STEM). However, the 3D shape and structure of GEMS grains and the spatial distribution of Fe/FeS's has critical information about their formation and origin. Recently, the 3D structure of GEMS grains in ultrathin sections of cluster IDPs was revealed by electron tomography using a TEM/STEM (JEM-2100F, JEOL). However, CT images of thin sections mounted on Cu grids acquired by conventional TEM-tomography are limited to low tilt angles (e. g., less than absolute value of 75 deg. In fact, previous 3D TEM observations of GEMS were affected by some artifacts related to the limited tilt range in the TEM used. Complete tomographic images should be acquired by rotating the sample tilt angle over a range of more than absolute value of 80 deg otherwise the CT images lose their correct structures. In order to constrain the origin and formation process of GEMS grains more clearly, we performed complete electron tomography for GEMS grains. Here we report the sample preparation method we have developed for this study, and the preliminary results.

  17. TEM sample preparation by femtosecond laser machining and ion milling for high-rate TEM straining experiments

    Energy Technology Data Exchange (ETDEWEB)

    Voisin, Thomas; Grapes, Michael D. [Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Zhang, Yong [Dept. of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States); Lorenzo, Nicholas; Ligda, Jonathan; Schuster, Brian [US Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, MD 21005 (United States); Weihs, Timothy P. [Dept. of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2017-04-15

    To model mechanical properties of metals at high strain rates, it is important to visualize and understand their deformation at the nanoscale. Unlike post mortem Transmission Electron Microscopy (TEM), which allows one to analyze defects within samples before or after deformation, in situ TEM is a powerful tool that enables imaging and recording of deformation and the associated defect motion during mechanical loading. Unfortunately, all current in situ TEM mechanical testing techniques are limited to quasi-static strain rates. In this context, we are developing a new test technique that utilizes a rapid straining stage and the Dynamic TEM (DTEM) at the Lawrence Livermore National Laboratory (LLNL). The new straining stage can load samples in tension at strain rates as high as 4×10{sup 3}/s using two piezoelectric actuators operating in bending while the DTEM at LLNL can image in movie mode with a time resolution as short as 70 ns. Given the piezoelectric actuators are limited in force, speed, and displacement, we have developed a method for fabricating TEM samples with small cross-sectional areas to increase the applied stresses and short gage lengths to raise the applied strain rates and to limit the areas of deformation. In this paper, we present our effort to fabricate such samples from bulk materials. The new sample preparation procedure combines femtosecond laser machining and ion milling to obtain 300 µm wide samples with control of both the size and location of the electron transparent area, as well as the gage cross-section and length. - Highlights: • Tensile straining TEM specimens made by femtosecond laser machining and ion milling. • Accurate positioning of the electron transparent area within a controlled gauge region. • Optimization of femtosecond laser and ion milling parameters. • Fast production of numerous samples with a highly repeatable geometry.

  18. Visualizing DNA Nanoparticle Motion under Graphene Liquid Cell TEM

    Science.gov (United States)

    Chen, Qian; Smith, Jessica; Park, Jungwon; Lee, Somin; Zettl, Alex; Alivisatos, Paul

    2013-03-01

    We think of a simple colloidal nanocrystal as one type of artificial atoms. They mutually interact, cluster into artificial molecules, and further arrange into macroscopically functional artificial solids. The ``atomic'' resolution dynamics of this bottom-up strategy in materials design is studied here in a system of artificial molecules composed of DNA and nanoparticle. The observation of dynamics in their liquid environment is recently enabled by graphene liquid cell transmission electron microscopy (TEM). In comparison to conventional TEM, wherein the assembled 3D artificial structures are dried out during sample preparation and thus are collapsed, this graphene liquid cell introduces a special local liquid structure that retains the conformations as well as the dynamics of the assemblies. In situ imaging of correlated motions of DNA and nanoparticle provides insights into the design principles of artificial nanocrystal molecules and solids linked by DNA.

  19. Imaging of Transient Structures Using Nanosecond in Situ TEM

    Science.gov (United States)

    Kim, Judy S.; LaGrange, Thomas; Reed, Bryan W.; Taheri, Mitra L.; Armstrong, Michael R.; King, Wayne E.; Browning, Nigel D.; Campbell, Geoffrey H.

    2008-09-01

    The microstructure and properties of a material depend on dynamic processes such as defect motion, nucleation and growth, and phase transitions. Transmission electron microscopy (TEM) can spatially resolve these nanoscale phenomena but lacks the time resolution for direct observation. We used a photoemitted electron pulse to probe dynamic events with “snapshot” diffraction and imaging at 15-nanosecond resolution inside of a dynamic TEM. With the use of this capability, the moving reaction front of reactive nanolaminates is observed in situ. Time-resolved images and diffraction show a transient cellular morphology in a dynamically mixing, self-propagating reaction front, revealing brief phase separation during cooling, and thus provide insights into the mechanisms driving the self-propagating high-temperature synthesis.

  20. TEM-145 and TEM-146 β-lactamases produced by Escherichia coli ...

    African Journals Online (AJOL)

    GREGO

    2007-03-05

    Mar 5, 2007 ... The β-lactamases with pI values of 6.0 and 6.6 could be identified as transcripts of. TEM β-lactamase genes and those with pI values of 7.8 and 8.6 as transcripts of the E. coli chromosomal AmpC genes. The TEM-β-lactamase enzymes showed the following changes compared to TEM-1: TEM-145 had two.

  1. TEM sample preparation by femtosecond laser machining and ion milling for high-rate TEM straining experiments.

    Science.gov (United States)

    Voisin, Thomas; Grapes, Michael D; Zhang, Yong; Lorenzo, Nicholas; Ligda, Jonathan; Schuster, Brian; Weihs, Timothy P

    2017-04-01

    To model mechanical properties of metals at high strain rates, it is important to visualize and understand their deformation at the nanoscale. Unlike post mortem Transmission Electron Microscopy (TEM), which allows one to analyze defects within samples before or after deformation, in situ TEM is a powerful tool that enables imaging and recording of deformation and the associated defect motion during mechanical loading. Unfortunately, all current in situ TEM mechanical testing techniques are limited to quasi-static strain rates. In this context, we are developing a new test technique that utilizes a rapid straining stage and the Dynamic TEM (DTEM) at the Lawrence Livermore National Laboratory (LLNL). The new straining stage can load samples in tension at strain rates as high as 4×10 3 /s using two piezoelectric actuators operating in bending while the DTEM at LLNL can image in movie mode with a time resolution as short as 70ns. Given the piezoelectric actuators are limited in force, speed, and displacement, we have developed a method for fabricating TEM samples with small cross-sectional areas to increase the applied stresses and short gage lengths to raise the applied strain rates and to limit the areas of deformation. In this paper, we present our effort to fabricate such samples from bulk materials. The new sample preparation procedure combines femtosecond laser machining and ion milling to obtain 300µm wide samples with control of both the size and location of the electron transparent area, as well as the gage cross-section and length. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Recent advances in cryo-TEM imaging of soft lipid nanoparticles

    DEFF Research Database (Denmark)

    Helvig, Shen Yu; Mat Azmi, Intan Diana Binti; Moghimi, Seyed Moien

    2015-01-01

    Cryo-transmission electron microscopy (Cryo-TEM), and its technological variations thereof, have become a powerful tool for detailed morphological characterization and 3D tomography of soft lipid and polymeric nanoparticles as well as biological materials such as viruses and DNA without chemical...... fixation. Here, we review and discuss recent advances in Cryo-TEM analysis of lipid-based drug nanocarriers with particular emphasis on morphological and internal nanostructure characterization of lyotropic liquid crystalline nanoparticles such as cubosomes and hexosomes....

  3. In situ TEM studies of local transport and structure in nanoscale multilayer films.

    Science.gov (United States)

    Chiaramonti, A N; Thompson, L J; Egelhoff, W F; Kabius, B C; Petford-Long, A K

    2008-11-01

    This paper describes a novel technique for studying structure-transport correlations in nanoscale multilayer thin films. Here, local current-voltage characteristics from simplified magnetic tunnel junctions are measured in situ on cross-sectional transmission electron microscopy (TEM) samples and correlated directly with TEM images of the microstructure at the tunneling site. It is found that local variations in barrier properties can be detected by a point probe method, and that the tunneling barrier height and width can be extracted.

  4. Towards an integrative structural biology approach: combining Cryo-TEM, X-ray crystallography, and NMR.

    Science.gov (United States)

    Lengyel, Jeffrey; Hnath, Eric; Storms, Marc; Wohlfarth, Thomas

    2014-09-01

    Cryo-transmission electron microscopy (Cryo-TEM) and particularly single particle analysis is rapidly becoming the premier method for determining the three-dimensional structure of protein complexes, and viruses. In the last several years there have been dramatic technological improvements in Cryo-TEM, such as advancements in automation and use of improved detectors, as well as improved image processing techniques. While Cryo-TEM was once thought of as a low resolution structural technique, the method is currently capable of generating nearly atomic resolution structures on a routine basis. Moreover, the combination of Cryo-TEM and other methods such as X-ray crystallography, nuclear magnetic resonance spectroscopy, and molecular dynamics modeling are allowing researchers to address scientific questions previously thought intractable. Future technological developments are widely believed to further enhance the method and it is not inconceivable that Cryo-TEM could become as routine as X-ray crystallography for protein structure determination.

  5. Development of a versatile TEM specimen holder for the characterization of photocatalytic materials

    DEFF Research Database (Denmark)

    Cavalca, Filippo; Langhammer, C.; Hansen, Thomas Willum

    2011-01-01

    Photocatalysts are of fundamental interest for sustainable energy research [1]. By means of transmission electron microscopy (TEM), it is possible to obtain insight into their structure, composition and reactivity. Such insight can then be used for their further optimization [2]. Here, we combine...... conventional TEM analysis on photocatalysts with several in situ TEM techniques including environmental TEM (ETEM), in situ photo activation and localized surface plasmon resonance (LSPR) spectroscopy [3-4]. These experiments are facilitated by the construction of a specimen holder capable of illuminating...... samples inside the TEM with a laser diode and an optical system to guide light onto the sample with maximum power transmission. The source can be changed and tuned between the visible and the UV range. The specimen holder is equipped with five electrical contacts that can be used to perform in situ...

  6. Quantitative TEM analysis of Al/Cu multilayer systems prepared by pulsed laser deposition

    DEFF Research Database (Denmark)

    Liu, Haihua; Pryds, Nini; Schou, Jørgen

    2010-01-01

    Thin films composed of alternating Al/Cu/Al layers were deposited on a (111) Si substrate using pulsed laser deposition (PLD). The thicknesses of the film and the individual layers, and the detailed internal structure within the layers were characterized by means of transmission electron microscopy...... (TEM), high-resolution TEM (HRTEM), and energy-filtered TEM (EFTEM). Each Al or Cu layer consists of a single layer of nano-sized grains of different orientations. EFTEM results revealed a layer of oxide about 2 nm thick on the surface of the Si substrate, which is considered to be the reason...

  7. Fluorescence microscopy.

    Science.gov (United States)

    Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

    2014-10-01

    Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

  8. Electron Microscopy.

    Science.gov (United States)

    Beer, Michael

    1980-01-01

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

  9. Compressive Classification for TEM-EELS

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Weituo; Stevens, Andrew; Yang, Hao; Gehm, Michael; Browning, Nigel D.

    2017-07-01

    Electron energy loss spectroscopy (EELS) is typically conducted in STEM mode with a spectrometer, or in TEM mode with energy selction. These methods produce a 3D data set (x, y, energy). Some compressive sensing [1,2] and inpainting [3,4,5] approaches have been proposed for recovering a full set of spectra from compressed measurements. In many cases the final form of the spectral data is an elemental map (an image with channels corresponding to elements). This means that most of the collected data is unused or summarized. We propose a method to directly recover the elemental map with reduced dose and acquisition time. We have designed a new computational TEM sensor for compressive classification [6,7] of energy loss spectra called TEM-EELS.

  10. A novel converter topology for TEM applications

    Indian Academy of Sciences (India)

    Time-domain Electro Magnetic (TEM) systems, are used for remote sensing of conductive mineral deposits buried under the surface of the earth. A low frequency trapezoidal current excitation set-up in an exciter coil loop causes a flux that penetrates deep into the earth. When the excitation is cut off sharply, conductive ...

  11. A novel converter topology for TEM applications

    Indian Academy of Sciences (India)

    and energy levels of the TEM system, require special type of excitation technique. Power converters for ... This paper proposes a novel converter topology to meet these excitation current require- ments. A novel ... The converter control system is given a square wave current reference of required amplitude,. ON duration TS ...

  12. XRD and TEM analysis of microstructure in the welding zone of 9Cr ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Under the condition of tungsten inert gas shielded welding (TIG) + shielded metal arc welding. (SMAW) technology, the microstructure in the welding zone of 9Cr–1Mo–V–Nb (P91) heat-resisting steel is studied by means of X-ray diffractometry (XRD) and transmission electron microscopy (TEM). The test.

  13. TEM characterization of La/B4C multilayer systems by the geometric phase method

    NARCIS (Netherlands)

    Häussler, D.; Spiecker, E.; Yang, S.; Jäger, W.; Störmer, M.; Bormann, R.; Zwicker, G.

    2005-01-01

    New La/B4C multilayer systems with layer thicknesses in the nanometer range have been deposited onto structured silicon (001) surfaces by magnetron sputtering and have been characterized by transmission electron microscopy (TEM). By applying a geometric phase method which has been originally

  14. Optical, mechanical and TEM assessment of titania-doped Bi2V1 ...

    Indian Academy of Sciences (India)

    Furthermore, analysis of transmission electron microscopy (TEM) images for all the oxides was conducted along with line spectra of planes. Results are discussed in light of correlation of these optical and mechanical parameters to their structural properties. Band gap has also been correlated to the conductivity of these ...

  15. Low-voltage and high-voltage TEM observations on MWCNTs of rat in vivo.

    Science.gov (United States)

    Sakaguchi, Norihito; Watari, Fumio; Yokoyama, Atsuro; Nodasaka, Yoshinobu; Ichinose, Hideki

    2009-01-01

    In the present study, we focused on the optimal conditions for observation of morphology and atomic structure of carbon nanotube (CNT) in vivo by transmission electron microscopy (TEM). Either low-voltage or high-voltage TEMs was chosen for the high-contrast or high-resolution imaging of subcutaneous tissue and the multi-wall CNT (MWCNT). The morphology and structure of each cell organelle were well recognized using the low-voltage TEM at 75 kV. Individual MWCNTs forming the cluster were also visible by the low-voltage TEM. On the contrary, the high-voltage TEM image at 1250 kV shows poor contrast on both the cell organelles and MWCNTs. However, graphene layers of MWCNT were clearly visible in the HRTEM image using the high-voltage TEM. The influence of the surrounding biological tissue can be disregarded by the high-energy electrons due to their weak scattering/absorption effect in the tissue. It was indicated that the usage of the high-voltage TEM is quite effective to the atomic structure analysis of nano-crystalline materials in vivo.

  16. TEM investigation of a microcline from a nepheline syenite

    Science.gov (United States)

    Smith, K. L.; McLaren, A. C.

    1983-11-01

    Chess-board (“tiled”) microcline crystals from a nepheline-bearing syenite from Ilimaussaq, W. Greenland, were investigated using transmission electron microscopy (TEM) and were found to consist of a mosaic of slightly misoriented domains, which bear no obvious relationship to the optical microstructure. Part of the misorientation of most pairs of neighbouring domains involves a small rotation about c. However, some are related to adjacent domains by the albite twin law, the pericline law, or diagonal association. This microcline could have crystallized with triclinic symmetry which could account for the differences between the microstructure of this microcline and M-twinned microcline. Metasomatism may explain both the optical microscope and TEM scale structures of this microcline. Examination of the electron diffraction patterns of areas of microcline which contain both diagonally associated and twinned domains draw attention to the fact that each of the few orientations in an M-twinned crystal is related to one of the other orientations by diagonal association. The formation of common cross-hatch twinned microstructures are discussed with reference to diagonal association.

  17. Preparation and Imaging of Specialized ER Using Super-Resolution and TEM Techniques.

    Science.gov (United States)

    Bell, Karen; Oparka, Karl; Knox, Kirsten

    2018-01-01

    The plant endoplasmic reticulum (ER) forms several specialized structures. These include the sieve element reticulum (SER) and the desmotubule formed as the ER passes through plasmodesmata. Imaging both of these structures has been inhibited by the resolution limits of light microscopy and their relatively inaccessible locations, combined with the fragile nature of the ER. Here we describe methods to view desmotubules in live cells under 3D-structured illumination microscopy (3D-SIM) and methods to fix and prepare phloem tissue for both 3D-SIM and transmission electron microscopy (TEM) which preserve the fragile structure and allow the detailed imaging of the SER.

  18. Acoustic microscopy

    CERN Document Server

    Briggs, Andrew

    2010-01-01

    For many years 'Acoustic Microscopy' has been the definitive book on the subject. A key development since it was first published has been the development of ultrasonic force microscopy. This edition has a major new chapter on this technique and its applications.

  19. Semiclassical TEM image formation in phase space.

    Science.gov (United States)

    Lubk, Axel; Röder, Falk

    2015-04-01

    Current developments in TEM such as high-resolution imaging at low acceleration voltages and large fields of view, the ever larger capabilities of hardware aberration correction and the systematic shaping of electron beams require accurate descriptions of TEM imaging in terms of wave optics. Since full quantum mechanic solutions have not yet been established for, e.g., the theory of aberrations, we are exploring semiclassical image formation in the TEM from the perspective of quantum mechanical phase space, here. Firstly, we use two well-known semiclassical approximations, Miller's semiclassical algebra and the frozen Gaussian method, for describing the wave optical generalization of arbitrary geometric aberrations, including nonisoplanatic and slope aberrations. Secondly, we demonstrate that the Wigner function representation of phase space is well suited to also describe incoherent aberrations as well as the ramifications of partial coherence due to the emission process at the electron source. We identify a close relationship between classical phase space and Wigner function distortions due to aberrations as well as classical brightness and quantum mechanical purity. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Comparative study of nanoscale surface structures of calcite microcrystals using FE-SEM, AFM, and TEM.

    Science.gov (United States)

    Chien, Yung-Ching; Mucci, Alfonso; Paquette, Jeanne; Sears, S Kelly; Vali, Hojatollah

    2006-08-01

    The bulk morphology and surface features that developed upon precipitation on micrometer-size calcite powders and millimeter-size cleavage fragments were imaged by three different microscopic techniques: field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) of Pt-C replicas, and atomic force microscopy (AFM). Each technique can resolve some nanoscale surface features, but they offer different ranges of magnification and dimensional resolutions. Because sample preparation and imaging is not constrained by crystal orientation, FE-SEM and TEM of Pt-C replicas are best suited to image the overall morphology of microcrystals. However, owing to the decoration effect of Pt-C on the crystal faces, TEM of Pt-C replicas is superior at resolving nanoscale surface structures, including the development of new faces and the different microtopography among nonequivalent faces in microcrystals, which cannot be revealed by FE-SEM. In conjunction with SEM, Pt-C replica provides the evidence that crystals grow in diverse and face-specific modes. The TEM imaging of Pt-C replicas has nanoscale resolution comparable to AFM. AFM yielded quantitative information (e.g., crystallographic orientation and height of steps) of microtopographic features. In contrast to Pt-C replicas and SEM providing three-dimensional images of the crystals, AFM can only image one individual cleavage or flat surface at a time.

  1. A nonlinear filtering algorithm for denoising HR(S)TEM micrographs

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hongchu, E-mail: h.du@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich Research Centre, Jülich, 52425 (Germany); Central Facility for Electron Microscopy (GFE), RWTH Aachen University, Aachen 52074 (Germany); Peter Grünberg Institute, Jülich Research Centre, Jülich 52425 (Germany)

    2015-04-15

    Noise reduction of micrographs is often an essential task in high resolution (scanning) transmission electron microscopy (HR(S)TEM) either for a higher visual quality or for a more accurate quantification. Since HR(S)TEM studies are often aimed at resolving periodic atomistic columns and their non-periodic deviation at defects, it is important to develop a noise reduction algorithm that can simultaneously handle both periodic and non-periodic features properly. In this work, a nonlinear filtering algorithm is developed based on widely used techniques of low-pass filter and Wiener filter, which can efficiently reduce noise without noticeable artifacts even in HR(S)TEM micrographs with contrast of variation of background and defects. The developed nonlinear filtering algorithm is particularly suitable for quantitative electron microscopy, and is also of great interest for beam sensitive samples, in situ analyses, and atomic resolution EFTEM. - Highlights: • A nonlinear filtering algorithm for denoising HR(S)TEM images is developed. • It can simultaneously handle both periodic and non-periodic features properly. • It is particularly suitable for quantitative electron microscopy. • It is of great interest for beam sensitive samples, in situ analyses, and atomic resolution EFTEM.

  2. Illuminating Electron Microscopy of Photocatalysts

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    Photocatalysts are of fundamental interest for sustainable energy research because of their wide range of applications and great potential for state of the art and future usages [1]. By means of Transmission Electron Microscopy (TEM) it is possible to give a deep insight in the structure......, composition and operation of photocatalysts and to provide information on the compounds inner arrangement and a fundamental contribution for their further optimization [2]. We want to construct a novel specimen holder capable of shining light onto samples inside the TEM allowing real time in situ experiments...... an Environmental TEM (ETEM) in order to expose the specimen to a controlled gas atmosphere during illumination. The aim is to perform complete and exhaustive characterization of photocatalytic materials under simulated working environment, achieving experimental data on yet uninvestigated aspects. Analysis can...

  3. Illuminating Electron Microscopy of Photocatalysts

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    Photocatalysts are of fundamental interest for sustainable energy research [1]. By means of transmission electron microscopy (TEM) it is possible to obtain deep insight in the structure, composition and reactivity of photocatalysts for their further optimization [2]. We have constructed a novel...... the device inside an environmental TEM (ETEM) in order to allow specimens to be exposed to controlled gas atmospheres during illumination. The holder is presently being used to study a variety of photoreactive materials and structures, including photocatalysts, photonic devices and solar cells. Here, we...... specimen holder capable of shining light onto samples inside the TEM. The holder contains a laser diode and an optical system that guides light onto a sample with maximum power transmission. The source can be changed and tuned, in principle spanning the whole visible and UV spectrum. It is possible to use...

  4. High-resolution electron microscopy

    CERN Document Server

    Spence, John C H

    2013-01-01

    This new fourth edition of the standard text on atomic-resolution transmission electron microscopy (TEM) retains previous material on the fundamentals of electron optics and aberration correction, linear imaging theory (including wave aberrations to fifth order) with partial coherence, and multiple-scattering theory. Also preserved are updated earlier sections on practical methods, with detailed step-by-step accounts of the procedures needed to obtain the highest quality images of atoms and molecules using a modern TEM or STEM electron microscope. Applications sections have been updated - these include the semiconductor industry, superconductor research, solid state chemistry and nanoscience, and metallurgy, mineralogy, condensed matter physics, materials science and material on cryo-electron microscopy for structural biology. New or expanded sections have been added on electron holography, aberration correction, field-emission guns, imaging filters, super-resolution methods, Ptychography, Ronchigrams, tomogr...

  5. TEM-EELS: A personal perspective

    Energy Technology Data Exchange (ETDEWEB)

    Egerton, R.F., E-mail: regerton@ualberta.ca [Physics Department, University of Alberta, Edmonton, Canada T6G 2E1 (Canada)

    2012-08-15

    The development of electron energy-loss spectroscopy in a transmission electron microscope (TEM-EELS) is illustrated through personal anecdote, highlighting some of the basic principles, instrumentation and personalities involved. The current state of the art is reviewed, together with some challenges for the future. -- Highlights: Black-Right-Pointing-Pointer The history of EELS instrumentation is reviewed in a lighthearted manner. Black-Right-Pointing-Pointer The current state of the art is summarized, together with some future possibilities. Black-Right-Pointing-Pointer A couple of related mathematical puzzles are offered as a challenge to the reader.

  6. TEM Study of SAFARI-2000 Aerosols

    Science.gov (United States)

    Buseck, Peter R.

    2004-01-01

    The aim of our research was to obtain data on the chemical and physical properties of individual aerosol particles from biomass smoke plume s in southern Africa and from air masses in the region that are affec ted by the smoke. We used analytical transmission electron microscopy (ATEM), including energy-dispersive X-ray spectrometry (EDS) and ele ctron energy-loss spectroscopy (EELS), and field-emission electron microscopy (FESEM) to study aerosol particles from several smoke and haz e samples and from a set of cloud samples.

  7. A simple algorithm for measuring particle size distributions on an uneven background from TEM images

    DEFF Research Database (Denmark)

    Gontard, Lionel Cervera; Ozkaya, Dogan; Dunin-Borkowski, Rafal E.

    2011-01-01

    Nanoparticles have a wide range of applications in science and technology. Their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we describe a simple computer algorithm for measuring particle size distributions from TEM images in the presence...... of an uneven background. The approach is based on adaptive thresholding, making use of local threshold values that change with spatial coordinate. The algorithm allows particles to be detected and characterized with greater accuracy than using more conventional methods, in which a global threshold is used. Its...

  8. Oxidation in ceria infiltrated metal supported SOFCs – A TEM investigation

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Wang, Hsiang-Jen; Blennow Tullmar, Peter

    2013-01-01

    The oxidation resistance of the Fe–Cr alloy backbone structure of metal supported solid oxide fuel cells is significantly improved when infiltrated with gadolinium doped ceria (CGO) particles. The mechanism for the improved oxidation behaviour is elucidated using various analytical transmission...... electron microscopy (TEM) techniques including energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy of focus ion beamed TEM samples. The infiltrated CGO is predominately converted into CeFeO3 after high temperature processing, protecting the alloy. A thin layer of Cr-oxide is observed...

  9. Simulation of topography evolution and damage formation during TEM sample preparation using focused ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Boxleitner, W. E-mail: wini@hobbit.fke.tuwien.ac.at; Hobler, G.; Klueppel, V.; Cerva, H

    2001-04-01

    Our recently developed simulation code FIBSIM is applied to topics related to transmission electron microscopy (TEM) sample preparation using focused ion beams (FIB). FIBSIM combines dynamic Monte Carlo simulation of collision cascades with two-dimensional, cell-based topography simulation. The influence of the scanning mode and of the beam current profile on the evolution of the surface contour is investigated. Furthermore, amorphous zones in silicon samples and damaged regions are predicted for different beam energies of 10, 30 and 50 keV. The thickness of the predicted amorphous regions is in good agreement with experimental TEM data.

  10. Correlative microscopy.

    Science.gov (United States)

    Loussert Fonta, Céline; Humbel, Bruno M

    2015-09-01

    In recent years correlative microscopy, combining the power and advantages of different imaging system, e.g., light, electrons, X-ray, NMR, etc., has become an important tool for biomedical research. Among all the possible combinations of techniques, light and electron microscopy, have made an especially big step forward and are being implemented in more and more research labs. Electron microscopy profits from the high spatial resolution, the direct recognition of the cellular ultrastructure and identification of the organelles. It, however, has two severe limitations: the restricted field of view and the fact that no live imaging can be done. On the other hand light microscopy has the advantage of live imaging, following a fluorescently tagged molecule in real time and at lower magnifications the large field of view facilitates the identification and location of sparse individual cells in a large context, e.g., tissue. The combination of these two imaging techniques appears to be a valuable approach to dissect biological events at a submicrometer level. Light microscopy can be used to follow a labelled protein of interest, or a visible organelle such as mitochondria, in time, then the sample is fixed and the exactly same region is investigated by electron microscopy. The time resolution is dependent on the speed of penetration and fixation when chemical fixatives are used and on the reaction time of the operator for cryo-fixation. Light microscopy can also be used to identify cells of interest, e.g., a special cell type in tissue or cells that have been modified by either transfections or RNAi, in a large population of non-modified cells. A further application is to find fluorescence labels in cells on a large section to reduce searching time in the electron microscope. Multiple fluorescence labelling of a series of sections can be correlated with the ultrastructure of the individual sections to get 3D information of the distribution of the marked proteins: array

  11. Tomographic Heating Holder for In Situ TEM

    DEFF Research Database (Denmark)

    Gontard, Lionel C.; Dunin-Borkowski, Rafal E.; Fernández, Asunción

    2014-01-01

    A tomographic heating holder for transmission electron microscopy that can be used to study supported catalysts at temperatures of up to ~1,500°C is described. The specimen is placed in direct thermal contact with a tungsten filament that is oriented perpendicular to the axis of the holder withou...

  12. Transmission electron microscopy in micro-nanoelectronics

    CERN Document Server

    Claverie, Alain

    2013-01-01

    Today, the availability of bright and highly coherent electron sources and sensitive detectors has radically changed the type and quality of the information which can be obtained by transmission electron microscopy (TEM). TEMs are now present in large numbers not only in academia, but also in industrial research centers and fabs.This book presents in a simple and practical way the new quantitative techniques based on TEM which have recently been invented or developed to address most of the main challenging issues scientists and process engineers have to face to develop or optimize sem

  13. Self-labelling enzymes as universal tags for fluorescence microscopy, super-resolution microscopy and electron microscopy

    Science.gov (United States)

    Liss, Viktoria; Barlag, Britta; Nietschke, Monika; Hensel, Michael

    2015-01-01

    Research in cell biology demands advanced microscopy techniques such as confocal fluorescence microscopy (FM), super-resolution microscopy (SRM) and transmission electron microscopy (TEM). Correlative light and electron microscopy (CLEM) is an approach to combine data on the dynamics of proteins or protein complexes in living cells with the ultrastructural details in the low nanometre scale. To correlate both data sets, markers functional in FM, SRM and TEM are required. Genetically encoded markers such as fluorescent proteins or self-labelling enzyme tags allow observations in living cells. Various genetically encoded tags are available for FM and SRM, but only few tags are suitable for CLEM. Here, we describe the red fluorescent dye tetramethylrhodamine (TMR) as a multimodal marker for CLEM. TMR is used as fluorochrome coupled to ligands of genetically encoded self-labelling enzyme tags HaloTag, SNAP-tag and CLIP-tag in FM and SRM. We demonstrate that TMR can additionally photooxidize diaminobenzidine (DAB) to an osmiophilic polymer visible on TEM sections, thus being a marker suitable for FM, SRM and TEM. We evaluated various organelle markers with enzymatic tags in mammalian cells labelled with TMR-coupled ligands and demonstrate the use as efficient and versatile DAB photooxidizer for CLEM approaches. PMID:26643905

  14. Chemical bioimaging for the subcellular localization of trace elements by high contrast TEM, TEM/X-EDS, and NanoSIMS.

    Science.gov (United States)

    Penen, Florent; Malherbe, Julien; Isaure, Marie-Pierre; Dobritzsch, Dirk; Bertalan, Ivo; Gontier, Etienne; Le Coustumer, Philippe; Schaumlöffel, Dirk

    2016-09-01

    Chemical bioimaging offers an important contribution to the investigation of biochemical functions, biosorption and bioaccumulation processes of trace elements via their localization at the cellular and even at the subcellular level. This paper describes the combined use of high contrast transmission electron microscopy (HC-TEM), energy dispersive X-ray spectroscopy (X-EDS), and nano secondary ion mass spectrometry (NanoSIMS) applied to a model organism, the unicellular green algae Chlamydomonas reinhardtii. HC-TEM providing a lateral resolution of 1nm was used for imaging the ultrastructure of algae cells which have diameters of 5-10μm. TEM coupled to X-EDS (TEM/X-EDS) combined textural (morphology and size) analysis with detection of Ca, P, K, Mg, Fe, and Zn in selected subcellular granules using an X-EDS probe size of approx. 1μm. However, instrumental sensitivity was at the limit for trace element detection. NanoSIMS allowed chemical imaging of macro and trace elements with subcellular resolution (element mapping). Ca, Mg, and P as well as the trace elements Fe, Cu, and Zn present at basal levels were detected in pyrenoids, contractile vacuoles, and granules. Some metals were even localized in small vesicles of about 200nm size. Sensitive subcellular localization of trace metals was possible by the application of a recently developed RF plasma oxygen primary ion source on NanoSIMS which has shown good improvements in terms of lateral resolution (below 50nm), sensitivity, and stability. Furthermore correlative single cell imaging was developed combining the advantages of TEM and NanoSIMS. An advanced sample preparation protocol provided adjacent ultramicrotome sections for parallel TEM and NanoSIMS analyses of the same cell. Thus, the C. reinhardtii cellular ultrastructure could be directly related to the spatial distribution of metals in different cell organelles such as vacuoles and chloroplast. Copyright © 2016 Elsevier GmbH. All rights reserved.

  15. Visualization of arrangements of carbon atoms in graphene layers by Raman mapping and atomic-resolution TEM

    KAUST Repository

    Cong, Chunxiao

    2013-02-01

    In-plane and out-of-plane arrangements of carbon atoms in graphene layers play critical roles in the fundamental physics and practical applications of these novel two-dimensional materials. Here, we report initial results on the edge/crystal orientations and stacking orders of bi-and tri-layer graphene (BLG and TLG) from Raman spectroscopy and transmission electron microscopy (TEM) experiments performed on the same sample. We introduce a new method of transferring graphene flakes onto a normal TEM grid. Using this novel method, we probed the BLG and TLG flakes that had been previously investigated by Raman scattering with high-resolution (atomic) TEM.

  16. Mitigating Curtaining Artifacts During Ga FIB TEM Lamella Preparation of a 14 nm FinFET Device.

    Science.gov (United States)

    Denisyuk, Andrey; Hrnčíř, Tomáš; Vincenc Oboňa, Jozef; Sharang; Petrenec, Martin; Michalička, Jan

    2017-06-01

    We report on the mitigation of curtaining artifacts during transmission electron microscopy (TEM) lamella preparation by means of a modified ion beam milling approach, which involves altering the incident angle of the Ga ions by rocking of the sample on a special stage. We applied this technique to TEM sample preparation of a state-of-the-art integrated circuit based on a 14-nm technology node. Site-specific lamellae with a thickness TEM, which showed a clear transistor structure and confirmed minimal curtaining artifacts. The results are compared with a standard inverted thinning preparation technique.

  17. Visualization of arrangements of carbon atoms in graphene layers by Raman mapping and atomic-resolution TEM

    Science.gov (United States)

    Cong, Chunxiao; Li, Kun; Zhang, Xi Xiang; Yu, Ting

    2013-01-01

    In-plane and out-of-plane arrangements of carbon atoms in graphene layers play critical roles in the fundamental physics and practical applications of these novel two-dimensional materials. Here, we report initial results on the edge/crystal orientations and stacking orders of bi- and tri-layer graphene (BLG and TLG) from Raman spectroscopy and transmission electron microscopy (TEM) experiments performed on the same sample. We introduce a new method of transferring graphene flakes onto a normal TEM grid. Using this novel method, we probed the BLG and TLG flakes that had been previously investigated by Raman scattering with high-resolution (atomic) TEM. PMID:23378926

  18. Vacancy ordering and superstructure formation in dry and hydrated strontium tantalate perovskites: A TEM perspective

    DEFF Research Database (Denmark)

    Ashok, Anuradha M.; Haavik, Camilla; Norby, Poul

    2014-01-01

    Crystal structures of Sr4(Sr2Ta2)O11 and Sr4(Sr1.92Ta2.08)O11.12, synthesized by solid state reaction technique in dry and hydrated state have been studied mainly using Transmission Electron Microscopy. Due to the lesser ability of X-rays to probe details in oxygen sublattice, the change in crystal...... symmetry due to ordering of oxygen vacancies could be detected better using Transmission Electron Microscopy. After detailed analysis through TEM, it was observed that no major change occurs in the cation sublattice. The TEM observations are compared with XRD data and discussed. The crystal symmetries...... structure. © 2014 Elsevier Ltd....

  19. TEM-145 and TEM-146 ß-lactamases produced by Escherichia coli ...

    African Journals Online (AJOL)

    Two Escherichia coli isolates which were isolated from the urine of patients in state hospitals in KwaZulu-Natal, South Africa were investigated to determine the sequence of the TEM -lactamases responsible for their resistance to -lactamase inhibitors. The isolates were subjected to MIC determinations, iso-electric focusing ...

  20. Characterization of Explosive Weld Joints by TEM and SEM/EBSD

    Directory of Open Access Journals (Sweden)

    Paul H.

    2014-10-01

    Full Text Available The layers near the interface of explosively welded plates were investigated by means of microscopic observations with the use of transmission electron microscopy (TEM equipped with energy dispersive spectrometry and scanning electron microscopy equipped with electron backscattered diffraction facility (SEM/EBSD. The metal compositions based on carbon or stainless steels (base plate and Ti, Zr and Ta (flyer plate were analyzed. The study was focused on the possible interdiffusion across the interface and the changes in the dislocation structure of bonded plates in the layers near-the-interface.

  1. TEM characterization of Cr-doped ZnS Thin Films for Solar Cell applications

    OpenAIRE

    Seim, Eivind

    2014-01-01

    The morphology of three Cr-doped zinc sulfide thin films, one deposited by molec-ular beam epitaxy (MBE) and two by pulsed laser deposition (PLD), have beenstudied by transmission electron microscopy (TEM). Investigations of the poly-morphic crystal structure of ZnS have been done by analysis of diffraction, brightfield and high resolution images. Both similarities and differences in morphologybetween the three samples have been discovered. An unambiguous determinationof the crystal structure...

  2. TEM EDS analysis of epitaxially-grown self-assembled indium islands

    Directory of Open Access Journals (Sweden)

    Jasmine Sears

    2017-05-01

    Full Text Available Epitaxially-grown self-assembled indium nanostructures, or islands, show promise as nanoantennas. The elemental composition and internal structure of indium islands grown on gallium arsenide are explored using Transmission Electron Microscopy (TEM Energy Dispersive Spectroscopy (EDS. Several sizes of islands are examined, with larger islands exhibiting high (>94% average indium purity and smaller islands containing inhomogeneous gallium and arsenic contamination. These results enable more accurate predictions of indium nanoantenna behavior as a function of growth parameters.

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

    DEFF Research Database (Denmark)

    Juul Jensen, D.

    1997-01-01

    The potentials of orientation mapping techniques (in the following referred to as OIM) for studies of thermomechanical processes are analysed. Both transmission electron microscopy (TEM) and scanning electron microscopy (SEM) based OIM techniques are considered. Among the thermomechanical processes...... information is achieved when the results of OIM and these various techniques are combined. Examples hereof are given to illustrate the potentials of OIM techniques. Finally, limitations of TEM and SEM based OIM for specific applications are discussed....

  4. Structural characterization of amphiphilic homopolymer micelles using light scattering, SANS, and cryo-TEM.

    Science.gov (United States)

    Patterson, Joseph P; Kelley, Elizabeth G; Murphy, Ryan P; Moughton, Adam O; Robin, Mathew; Lu, Annhelen; Colombani, Olivier; Chassenieux, Christophe; Cheung, David; Sullivan, Millicent O; Epps, Thomas H; O'Reilly, Rachel K

    2013-08-13

    We report the aqueous solution self-assembly of a series of poly(N-isopropylacrylamide) (PNIPAM) polymers end-functionalized with a hydrophobic sulfur-carbon-sulfur (SCS) pincer ligand. Although the hydrophobic ligand accounted for structural details were investigated using light scattering, cryogenic transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS). Radial density profiles extracted from the cryo-TEM micrographs suggested that the PNIPAM chains formed a diffuse corona with a radially decreasing corona density profile and provided valuable a priori information about the micelle structure for SANS data modeling. SANS analysis indicated a similar profile in which the corona surrounded a small hydrophobic core containing the pincer ligand. The similarity between the SANS and cryo-TEM results demonstrated that detailed information about the micelle density profile can be obtained directly from cryo-TEM and highlighted the complementary use of scattering and cryo-TEM in the structural characterization of solution-assemblies, such as the SCS pincer-functionalized homopolymers described here.

  5. Polarized Light Microscopy

    Science.gov (United States)

    Frandsen, Athela F.

    2016-01-01

    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  6. Cryo-TEM analysis of collagen fibrillar structure.

    Science.gov (United States)

    Quan, Bryan D; Sone, Eli D

    2013-01-01

    Fibrillar collagens are important structural proteins and are known to be closely associated with mineral in the case of mineralized tissues. However, the precise role of collagen in the mineralization process remains unclear, and the evaluation of structural differences in collagen from mineralized and nonmineralized tissues may be instructive in this regard. Here, we review the use of cryo-transmission electron microscopy to investigate the axial structure of collagen fibrils in tissue sections from both mineralizing and nonmineralizing tissues. By examining collagen fibrillar structure in an unstained frozen-hydrated state, it is possible to avoid artifacts normally associated with staining and dehydration that are required for conventional TEM. We describe both sample preparation and image analysis with emphasis on the particular challenges of using image averaging techniques, which can be used to overcome the low signal-to-noise ratio that is inherent in this technique. Detailed banding patterns can be obtained from averaged images, and these can be analyzed to obtain quantitative information on fibril periodicity and structure. © 2013 Elsevier Inc. All rights reserved.

  7. Advanced electron microscopy characterization of nanomaterials for catalysis

    Directory of Open Access Journals (Sweden)

    Dong Su

    2017-04-01

    Full Text Available Transmission electron microscopy (TEM has become one of the most powerful techniques in the fields of material science, inorganic chemistry and nanotechnology. In terms of resolutions, advanced TEM may reach a high spatial resolution of 0.05 nm, a high energy-resolution of 7 meV. In addition, in situ TEM can help researchers to image the process happened within 1 ms. This paper reviews the recent technical progresses of applying advanced TEM characterization on nanomaterials for catalysis. The text is organized based on the perspective of application: for example, size, composition, phase, strain, and morphology. The electron beam induced effect and in situ TEM are also introduced. I hope this review can help the scientists in related fields to take advantage of advanced TEM to their own researches. Keywords: Advanced TEM, Nanomaterials, Catalysts, In situ

  8. Electron microscopy study of refractory ceramic fibers.

    Science.gov (United States)

    MacKinnon, P A; Lentz, T J; Rice, C H; Lockey, J E; Lemasters, G K; Gartside, P S

    2001-10-01

    In epidemiological studies designed to identify potential health risks of exposures to synthetic vitreous fibers, the characterization of airborne fiber dimensions may be essential for assessing mechanisms of fiber toxicity. Toward this end, air sampling was conducted as part of an industry-wide study of workers potentially exposed to airborne fibrous dusts during the manufacture of refractory ceramic fibers (RCF) and RCF products. Analyses of a subset of samples obtained on the sample filter as well as on the conductive sampling cowl were performed using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to characterize dimensions of airborne fibers. Comparison was made of bivariate fiber size distributions (length and diameter) from air samples analyzed by SEM and by TEM techniques. Results of the analyses indicate that RCF size distributions include fibers small enough in diameter (fibers (> 60 microm) may go undetected by TEM, as evidenced by the proportion of fibers in this category for TEM and SEM analyses (1% and 5%, respectively). Limitations of the microscopic techniques and differences in fiber-sizing rules for each method are believed to have contributed to the variation among fiber-sizing results. It was concluded from these data that further attempts to characterize RCF exposure in manufacturing and related operations should include analysis by TEM and SEM, since the smallest diameter fibers are not resolved with SEM and the fibers of longer length are not sized by TEM.

  9. Use of atomic force microscopy and transmission electron microscopy for correlative studies of bacterial capsules.

    Science.gov (United States)

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

    2008-09-01

    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.

  10. Metrology of DSA process using TEM tomography

    Science.gov (United States)

    Segal-Peretz, Tamar; Winterstein, Jonathan; Ren, Jiaxing; Biswas, Mahua; Liddle, J. Alexander; Elam, Jeffery W.; Ocola, Leonidas E.; Divan, Ralu N. S.; Zaluzec, Nestor; Nealey, Paul F.

    2015-03-01

    Directed self-assembly (DSA) of block copolymers (BCPs) is a rising technique for sub-20 nm patterning. To fully harness DSA capabilities for patterning, a detailed understanding of the three dimensional (3D) structure of BCPs is needed. By combining sequential infiltration synthesis (SIS) and scanning transmission electron microscopy (STEM) tomography, we have characterized the 3D structure of self-assembled and DSA BCPs films with high precision and resolution. SIS is an emerging technique for enhancing pattern transfer in BCPs through the selective growth of inorganic material in polar BCP domains. Here, Al2O3 SIS was used to enhance the imaging contrast and enable tomographic characterization of BCPs with high fidelity. Moreover, by utilizing SIS for both 3D characterization and hard mask fabrication, we were able to characterize the BCP morphology as well as the alumina nanostructures that would be used for pattern transfer.

  11. Shining light on the Environmental TEM

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Cavalca, Filippo; Hansen, Thomas Willum

    of the major challenges when studying the effects of visible light in the electron microscope is to differentiate between the effect of visible light and that of high-energy electrons. New protocols for acquisition and robust interpretation of in situ data on photocatalysts are needed to minimize the effect......Digging into the world of photocatalysts by means of electron microscopy gives rise to new challenges. In order to study photocatalysts under working conditions, a holder capable of exposing a sample to visible light in situ during gas exposure in the ETEM has been developed at DTU Cen1. One...... of the electron beam without compromising image quality and information to exploit the full potential of in situ light stimuli. A major parameter degrading the image quality in ETEM is the gas-electron interactions. Even though high-resolution ETEMs have been around for more than a decade little has been done...

  12. Characterization of the system MoS{sub 2} + C, HAADF vs Tem conventional; Cracterizacion del sistema MoS{sub 2} + C, HAADF vs TEM convencional

    Energy Technology Data Exchange (ETDEWEB)

    Reza, C.; Cruz, G. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Santiago, P.; Rendon, L. [IFUNAM, A.P. 20-364, 04510 Mexico D.F. (Mexico)

    2004-07-01

    A study is presented about the synthesis and characterization of unidimensional nano systems composed of MoS{sub 2} and C with potential use as solid lubricant. The synthesis process was developed for the mold method, via thermal decomposition, which uses a film of nano porous aluminium oxide. Such systems were characterized by two analysis methods that involve Transmission Electron Microscopy, HRTEM (Conventional TEM) and HAADF (Z Contrast). The results obtained in the structural and morphological characterization were supplemented to determine the structure type obtained in the unidimensional systems. (Author)

  13. Comprehensive analysis of TEM methods for LiFePO4/FePO4 phase mapping: spectroscopic techniques (EFTEM, STEM-EELS) and STEM diffraction techniques (ACOM-TEM)

    DEFF Research Database (Denmark)

    Mu, X.; Kobler, A.; Wang, D.

    2016-01-01

    Transmission electron microscopy (TEM) has been used intensively in investigating battery materials, e.g. to obtain phase maps of partially (dis)charged (lithium) iron phosphate (LFP/FP), which is one of the most promising cathode material for next generation lithium ion (Li-ion) batteries. Due...... to the weak interaction between Li atoms and fast electrons, mapping of the Li distribution is not straightforward. In this work, we revisited the issue of TEM measurements of Li distribution maps for LFP/FP. Different TEM techniques, including spectroscopic techniques (energy filtered (EF)TEM in the energy...... with each other. Because of the strong difference in the imaging mechanisms, it proves the reliability of both the spectroscopic and STEM diffraction phase mapping. A comprehensive comparison of all methods is given in terms of information content, dose level, acquisition time and signal quality. The latter...

  14. In situ TEM analysis of a symmetric solid oxide cell in oxygen and vacuum–cation diffusion observations

    DEFF Research Database (Denmark)

    Gualandris, Fabrizio; Simonsen, Søren Bredmose; Wagner, Jakob Birkedal

    2017-01-01

    In order to establish the use of solid oxide fuel/electrolysis cells (SOFC/SOEC) in the energy market, a deeper understanding of degradation effects during operation is necessary. This study apply in situ transmission electron microscopy (TEM) of a symmetric model cell composed by two oxygen...

  15. Characterization of nanomaterials with transmission electron microscopy

    KAUST Repository

    Anjum, Dalaver H.

    2016-08-01

    The field of nanotechnology is about research and development on materials whose at least one dimension is in the range of 1 to 100 nanometers. In recent years, the research activity for developing nano-materials has grown exponentially owing to the fact that they offer better solutions to the challenges faced by various fields such as energy, food, and environment. In this paper, the importance of transmission electron microscopy (TEM) based techniques is demonstrated for investigating the properties of nano-materials. Specifically the nano-materials that are investigated in this report include gold nano-particles (Au-NPs), silver atom-clusters (Ag-ACs), tantalum single-atoms (Ta-SAs), carbon materials functionalized with iron cobalt (Fe-Co) NPs and titania (TiO2) NPs, and platinum loaded Ceria (Pt-CeO2) Nano composite. TEM techniques that are employed to investigate nano-materials include aberration corrected bright-field TEM (BF-TEM), high-angle dark-field scanning TEM (HAADF-STEM), electron energy-loss spectroscopy (EELS), and BF-TEM electron tomography (ET). With the help presented of results in this report, it is proved herein that as many TEM techniques as available in a given instrument are essential for a comprehensive nano-scale analysis of nanomaterials.

  16. Oil refinery dusts: morphological and size analysis by TEM

    Energy Technology Data Exchange (ETDEWEB)

    Sielicki, Przemyslaw; Janik, Helena; Guzman, Agnieszka [Gdansk University of Technology, Department of Polymer Technology, Chemical Faculty, Gdansk (Poland); Broniszewski, Mieczyslaw [Environmental Protection Office, Lotos Group, Gdansk (Poland); Namiesnik, Jacek [Gdansk University of Technology, Department of Analytical Chemistry, Chemical Faculty, Gdansk (Poland)

    2011-03-15

    The objectives of this work were to develop a means of sampling atmospheric dusts on the premises of an oil refinery for electron microscopic study to carry out preliminary morphological analyses and to compare these dusts with those collected at sites beyond the refinery limits. Carbon and collodion membranes were used as a support for collection of dust particles straight on transmission electron microscopy (TEM) grids. Micrographs of the dust particles were taken at magnifications from x 4,000 to x 80,000 with a Tesla BS500 transmission electron microscope. Four parameters were defined on the basis of the micrographs: surface area, Feret diameter, circumference, and shape coefficient. The micrographs and literature data were used to classify the atmospheric dusts into six groups: particles with an irregular shape and rounded edges; particles with an irregular shape and sharp edges; soot and its aggregates; spherical particles; singly occurring, ultrafine dust particles; and particles not allocated to any of the previous five groups. The types of dusts found in all the samples were similar, although differences did exist between the various morphological parameters. Dust particles with the largest Feret diameter were present in sample 3 (mean, 0.739 {mu}m) - these were collected near the refinery's effluent treatment plant. The particles with the smallest diameter were found in the sample that had been intended to be a reference sample for the remaining results (mean, 0.326 {mu}m). The dust particles collected in the refinery had larger mean Feret diameters, even 100% larger, than those collected beyond it. Particles with diameters from 0.1 to 0.2 {mu}m made up the most numerous group in all the samples collected in the refinery. (orig.)

  17. Oil refinery dusts: morphological and size analysis by TEM.

    Science.gov (United States)

    Sielicki, Przemysław; Janik, Helena; Guzman, Agnieszka; Broniszewski, Mieczysław; Namieśnik, Jacek

    2011-03-01

    The objectives of this work were to develop a means of sampling atmospheric dusts on the premises of an oil refinery for electron microscopic study to carry out preliminary morphological analyses and to compare these dusts with those collected at sites beyond the refinery limits. Carbon and collodion membranes were used as a support for collection of dust particles straight on transmission electron microscopy (TEM) grids. Micrographs of the dust particles were taken at magnifications from ×4,000 to ×80,000 with a Tesla BS500 transmission electron microscope. Four parameters were defined on the basis of the micrographs: surface area, Feret diameter, circumference, and shape coefficient. The micrographs and literature data were used to classify the atmospheric dusts into six groups: particles with an irregular shape and rounded edges; particles with an irregular shape and sharp edges; soot and its aggregates; spherical particles; singly occurring, ultrafine dust particles; and particles not allocated to any of the previous five groups. The types of dusts found in all the samples were similar, although differences did exist between the various morphological parameters. Dust particles with the largest Feret diameter were present in sample 3 (mean, 0.739 μm)-these were collected near the refinery's effluent treatment plant. The particles with the smallest diameter were found in the sample that had been intended to be a reference sample for the remaining results (mean, 0.326 μm). The dust particles collected in the refinery had larger mean Feret diameters, even 100% larger, than those collected beyond it. Particles with diameters from 0.1 to 0.2 μm made up the most numerous group in all the samples collected in the refinery.

  18. Progress in the preparation of cross-sectional TEM specimens by ion-beam thinning

    CERN Document Server

    Strecker, A; Kelsch, M; Salzberger, U; Sycha, M; Gao, M; Richter, G; Benthem, K V

    2003-01-01

    In transmission electron microscopy (TEM), often the preparation of samples is the most critical part. Specimens have to have disk geometries of 3 mm diameter laterally, and they have to be transparent for the electron beam vertically. Therefore, a specimen thickness in the range of some 1-10 nm has to be achieved by the preparation process. While shrinking the specimen dimensions, care has to be taken to recover the materials properties in the nm-regime. We report and shortly discuss some TEM specimen preparation techniques mainly used in the Stuttgart TEM specimen preparation laboratory. Furthermore, we demonstrate how more advanced techniques lead to a more reliable preparation of weakly-bonded metal/SrTiO sub 3 interfaces. In addition, the advantage of low-voltage ion-milling is demonstrated by a case study for bulk SrTiO sub 3. As a result, low-voltage ion polishing as a final step in the TEM specimen preparation by conventional ion-thinning turns out to significantly increase the specimen quality. In tu...

  19. Bonding and structure of a reconstructed (001) surface of SrTiO3 from TEM.

    Science.gov (United States)

    Zhu, Guo-zhen; Radtke, Guillaume; Botton, Gianluigi A

    2012-10-18

    The determination of the atomic structure and the retrieval of information about reconstruction and bonding of metal oxide surfaces is challenging owing to the highly defective structure and insulating properties of these surfaces. Transmission electron microscopy (TEM) offers extremely high spatial resolution (less than one ångström) and the ability to provide systematic information from both real and reciprocal space. However, very few TEM studies have been carried out on surfaces because the information from the bulk dominates the very weak signals originating from surfaces. Here we report an experimental approach to extract surface information effectively from a thickness series of electron energy-loss spectra containing different weights of surface signals, using a wedge-shaped sample. Using the (001) surface of the technologically important compound strontium titanate, SrTiO(3) (refs 4-6), as a model system for validation, our method shows that surface spectra are sensitive to the atomic reconstruction and indicate bonding and crystal-field changes surrounding the surface Ti cations. Very good agreement can be achieved between the experimental surface spectra and crystal-field multiplet calculations based on the proposed atomic surface structure optimized by density functional calculations. The distorted TiO(6-x) units indicated by the proposed model can be viewed directly in our high-resolution scanning TEM images. We suggest that this approach be used as a general method to extract valuable spectroscopic information from surface atoms in parallel with high-resolution images in TEM.

  20. Soft nanomaterials analysed by in situ liquid TEM: Towards high resolution characterisation of nanoparticles in motion

    Directory of Open Access Journals (Sweden)

    Joseph P. Patterson

    2015-12-01

    Full Text Available In this article we present in situ transmission electron microscopy (TEM of soft, synthetic nanoparticles with a comparative analysis using conventional TEM methods. This comparison is made with the simple aim of describing what is an unprecedented example of in situ imaging by TEM. However, we contend the technique will quickly become essential in the characterisation of analogous systems, especially where dynamics are of interest in the solvated state. In this case, particles were studied which were obtained from the direct polymerisation of an oxaliplatin analogue, designed for an ongoing programme in novel chemotherapeutic delivery systems. The resulting nanoparticles provided sufficient contrast for facile imaging in situ, and point towards key design parameters that enable this new characterisation approach for organic nanomaterials. We describe the preparation of the synthetic nanoparticles together with their characterisation in liquid water. Finally, we provide a future perspective of this technique for the analysis of soft and dynamic nanomaterials and discussion the progress which needs to be made in order to bring in situ liquid TEM to its full potential.

  1. Reduction reactions and densification during in situ TEM heating of iron oxide nanochains

    Science.gov (United States)

    Bonifacio, Cecile S.; Das, Gautom; Kennedy, Ian M.; van Benthem, Klaus

    2017-12-01

    The reduction reactions and densification of nanochains assembled from γ-Fe2O3 nanoparticles were investigated using in situ transmission electron microscopy (TEM). Morphological changes and reduction of the metal oxide nanochains were observed during in situ TEM annealing through simultaneous imaging and quantitative analysis of the near-edge fine structures of Fe L2,3 absorption edges acquired by spatially resolved electron energy loss spectroscopy. A change in the oxidation states during annealing of the iron oxide nanochains was observed with phase transformations due to continuous reduction from Fe2O3 over Fe3O4, FeO to metallic Fe. Phase transitions during the in situ heating experiments were accompanied with morphological changes in the nanochains, specifically rough-to-smooth surface transitions below 500 °C, neck formation between adjacent particles around 500 °C, and subsequent neck growth. At higher temperatures, coalescence of FeO particles was observed, representing densification.

  2. Determination of Size Distributions in Nanocrystalline Powders by TEM, XRD and SAXS

    DEFF Research Database (Denmark)

    Jensen, Henrik; Pedersen, Jørgen Houe; Jørgensen, Jens Erik

    2006-01-01

    Crystallite size distributions and particle size distributions were determined by TEM, XRD, and SAXS for three commercially available TiO2 samples and one homemade. The theoretical Guinier Model was fitted to the experimental data and compared to analytical expressions. Modeling of the XRD spectra...... the size distribution obtained from the XRD experiments; however, a good agreement was obtained between the two techniques. Electron microscopy, SEM and TEM, confirmed the primary particle sizes, the size distributions, and the shapes obtained by XRD and SAXS. The SSEC78 powder and the commercially...... available powders showed different morphologies. The SSEC78 powder showed the narrowest sizes distribution while UV100 and TiO2_5nm consisted of the smallest primary particles. SSEC78, UV100, and TiO2_5nm consisted of both primary particles as well as a secondary structure comprised of nanosized primary...

  3. Electrochemical loading of TEM grids used for the study of potential dependent morphology of polyaniline nanofibres.

    Science.gov (United States)

    Bhadu, Gopala Ram; Paul, Anirban; Perween, Mosarrat; Gupta, Rajeev; Chaudhari, Jayesh C; Srivastava, Divesh N

    2016-03-01

    An electrochemical method for loading electroactive materials over the TEM grid is reported. The protocol has been demonstrated using polyaniline as an example. The electroactive polymer was directly deposited over the Au TEM grid, used as working electrode in a 3 electrode electrochemical cell. The undisturbed as-deposited morphologies under the influence of various counter ions and ex situ electrochemical states have been studied and compared. Contrary to behaviour in bulk the individual polyaniline fibre was found thinner at anodic potentials. The movement of counter ions as a function of the electrochemical state of the polymer was studied using STEM-EDX elemental mapping. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  4. Size Dependent Pore Formation in Germanium Nanowires Undergoing Reversible Delithiation Observed by In Situ TEM

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xiaotang; He, Yang; Mao, Scott X.; Wang, Chong-min; Korgel, Brian A.

    2016-12-22

    Germanium (Ge) nanowires coated with an amorphous silicon (Si) shell undergoing lithiation and delithiation were studied using in situ transmission electron microscopy (TEM). Delithiation creates pores in nanowires with diameters larger than ~25 nm, but not in smaller diameter nanowires. The formation of pores in Ge nanowires undergoing delithiation has been observed before in in situ TEM experiments, but there has been no indication that a critical diameter exists below which pores do not form. Pore formation occurs as a result of fast lithium diffusion compared to vacancy migration. We propose that a short diffusion path for vacancies to the nanowire surface plays a role in limiting pore formation even when lithium diffusion is fast.

  5. Deformation mechanisms in naturally deformed glaucophanes: A TEM and HREM study

    Energy Technology Data Exchange (ETDEWEB)

    Reynard, B.; Gillet, P.; Willaime, C. (Lab. de Mineralogie Physique, Centre Armoricain d' Etude Structurale des Socles, Univ. de Rennes, 35 (France))

    Deformation mechanisms of glaucophane have been investigated on two naturally deformed samples by optical and TEM microscopy. The two samples were deformed under eclogite facies conditions (15-18 kbar, 550-600 degC); one sample suffered in addition a later greenschist deformation (< 10 kbar, 350-450 degC). Under the optical microscope, the glaucophanes display intracrystalline deformation features (undulose extinction, subgrains). TEM observations reveal the operation of glide on several systems: (100)[001], [l brace]110[r brace][001], (010)[100], [l brace]110[r brace] 1/2<1anti 10> and (001) 1/2<110> at medium temperature (550-600 degC) and (010)[001] at low temperature (350-450 degC). Minor (100) twinning is associated. The presence of subgrains bounded by well-organized dislocation walls indicates that recovery processes are active.

  6. The Structural Bases of Antibiotic Resistance in the Clinically Derived Mutant beta-Lactamases TEM-30, TEM-32, and TEM-34

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun; Minasov, George; Shoichet, Brian K. (NWU)

    2010-03-08

    Widespread use of {beta}-lactam antibiotics has promoted the evolution of {beta}-lactamase mutant enzymes that can hydrolyze ever newer classes of these drugs. Among the most pernicious mutants are the inhibitor-resistant TEM {beta}-lactamases (IRTs), which elude mechanism-based inhibitors, such as clavulanate. Despite much research on these IRTs, little is known about the structural bases of their action. This has made it difficult to understand how many of the resistance substitutions act as they often occur far from Ser-130. Here, three IRT structures, TEM-30 (R244S), TEM-32 (M69I/M182T), and TEM-34 (M69V), are determined by x-ray crystallography at 2.00, 1.61, and 1.52 {angstrom}, respectively. In TEM-30, the Arg-244 {yields} Ser substitution (7.8 {angstrom} from Ser-130) displaces a conserved water molecule that usually interacts with the {beta}-lactam C3 carboxylate. In TEM-32, the substitution Met-69 {yields} Ile (10 {angstrom} from Ser-130) appears to distort Ser-70, which in turn causes Ser-130 to adopt a new conformation, moving its O{gamma} further away, 2.3 {angstrom} from where the inhibitor would bind. This substitution also destabilizes the enzyme by 1.3 kcal/mol. The Met-182 {yields} Thr substitution (20 {angstrom} from Ser-130) has no effect on enzyme activity but rather restabilizes the enzyme by 2.9 kcal/mol. In TEM-34, the Met-69 {yields} Val substitution similarly leads to a conformational change in Ser-130, this time causing it to hydrogen bond with Lys-73 and Lys-234. This masks the lone pair electrons of Ser-130 O{gamma}, reducing its nucleophilicity for cross-linking. In these three structures, distant substitutions result in accommodations that converge on the same point of action, the local environment of Ser-130. TEM-1 {beta}-lactamase is the predominant source of resistance to {beta}-lactams, such as the penicillins. TEM-1 and related class A {beta}-lactamases confer resistance by hydrolyzing the {beta}-lactam ring of these antibiotics

  7. Microstructural observation of fuel cell catalyst inks by Cryo-SEM and Cryo-TEM.

    Science.gov (United States)

    Shimanuki, Junichi; Takahashi, Shinichi; Tohma, Hajime; Ohma, Atsushi; Ishihara, Ayumi; Ito, Yoshiko; Nishino, Yuri; Miyazawa, Atsuo

    2017-06-01

    In order to improve the electricity generation performance of fuel cell electric vehicles, it is necessary to optimize the microstructure of the catalyst layer of a polymer electrolyte fuel cell. The catalyst layer is formed by a wet coating process using catalyst inks. Therefore, it is very important to observe the microstructure of the catalyst ink. In this study, the morphology of carbon-supported platinum (Pt/C) particles in catalyst inks with a different solvent composition was investigated by cryogenic scanning electron microscopy (cryo-SEM). In addition, the morphology of the ionomer, which presumably influences the formation of agglomerated Pt/C particles in a catalyst ink, was investigated by cryogenic transmission electron microscopy (cryo-TEM). The results of a cryo-SEM observation revealed that the agglomerated Pt/C particles tended to become coarser with a higher 1-propanol (NPA) weight fraction. The results of a cryo-TEM observation indicated that the actual ionomer dispersion in a catalyst ink formed a network structure different from that of the ionomer in the solvent. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Recognition and Resistance in TEM [superscript beta]-Lactamase

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun; Minasov, George; Blazquez, Jesus; Caselli, Emilia; Prati, Fabio; Shoichet, Brian K. (Degli); (UCSF)

    2010-03-08

    Developing antimicrobials that are less likely to engender resistance has become an important design criterion as more and more drugs fall victim to resistance mutations. One hypothesis is that the more closely an inhibitor resembles a substrate, the more difficult it will be to develop resistant mutations that can at once disfavor the inhibitor and still recognize the substrate. To investigate this hypothesis, 10 transition-state analogues, of greater or lesser similarity to substrates, were tested for inhibition of TEM-1 beta-lactamase, the most widespread resistance enzyme to penicillin antibiotics. The inhibitors were also tested against four characteristic mutant enzymes: TEM-30, TEM-32, TEM-52, and TEM-64. The inhibitor most similar to the substrate, compound 10, was the most potent inhibitor of the WT enzyme, with a K(i) value of 64 nM. Conversely, compound 10 was the most susceptible to the TEM-30 (R244S) mutant, for which inhibition dropped by over 100-fold. The other inhibitors were relatively impervious to the TEM-30 mutant enzyme. To understand recognition and resistance to these transition-state analogues, the structures of four of these inhibitors in complex with TEM-1 were determined by X-ray crystallography. These structures suggest a structural basis for distinguishing inhibitors that mimic the acylation transition state and those that mimic the deacylation transition state; they also suggest how TEM-30 reduces the affinity of compound 10. In cell culture, this inhibitor reversed the resistance of bacteria to ampicillin, reducing minimum inhibitory concentrations of this penicillin by between 4- and 64-fold, depending on the strain of bacteria. Notwithstanding this activity, the resistance of TEM-30, which is already extant in the clinic, suggests that there can be resistance liabilities with substrate-based design.

  9. Characterization of isolated polyamide thin films of RO and NF membranes using novel TEM techniques

    KAUST Repository

    Pacheco, Federico A.

    2010-08-15

    Achieving a better understanding of transport and rejection mechanisms in RO and NF membranes requires more detailed information of the nanostructure of polyamide thin films. This study reports on two novel transmission electron microscopy (TEM) techniques for characterizing polyamide nanostructure. The first technique produces cross-sectional images of isolated polyamide thin films by removing the polysulfone support from regular TEM cross-sections. In the second technique called " projected area" TEM (PA-TEM), isolated polyamide thin films are placed with their surface perpendicular to the electron beam. The resulting images capture the thickness, morphology and mass density of the entire thin film. In combination, these new techniques provide information on polyamide nanostructure that is not evident using conventional methods. For the commercial RO membrane ESPA3, the cross-sectional view of the isolated polyamide thin film shows a 30-60. nm thick base of nodular polyamide (presumably the separation barrier) that forms a relatively smooth interface with the polysulfone support. Above this, a more open structure of loose polyamide extends outward giving rise to the ridge-and-valley surface structure. In PA-TEM images, the ridges and valleys correspond to the dark and bright regions, respectively; the polyamide nodular base appears as round features forming an irregular honeycomb pattern throughout the images. Membrane cross-sections were prepared with a simple resin embedding protocol using the acrylic resin LR White. The protocol did not require dehydration steps, and was applicable to both dry and wet membrane samples. Artifacts that may be produced during sample preparation were also documented. © 2010 Elsevier B.V.

  10. TOPICAL REVIEW: Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials

    Directory of Open Access Journals (Sweden)

    Nobuo Tanaka

    2008-01-01

    Full Text Available The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy.

  11. In situ sputter cleaning of thin film metal substrates for UHV-TEM corrosion studies.

    Science.gov (United States)

    Heinemann, K.; Poppa, H.

    1973-01-01

    A prerequisite for conducting valid corrosion experiments by in situ electron microscopy techniques is not only the achievement of UHV background pressure conditions at the site of the specimen but also the ability to clean the surface of the thin metal substrate specimen before initiation of the corrosive interaction. A miniaturized simple ion gun has been constructed for this purpose. The gun is small enough to be incorporated into an UHV electron microscope specimen chamber with hot stage in such a way as to permit bombardment of the substrate specimen while observing it by transmission electron microscopy TEM. It is shown that the ion beam generated is confined well enough to cause a sputtering removal of substrate material at a rate of approximately 5-10 A/min and to prevent the sputter deposition of contaminating material from the specimen holder.

  12. Transmission electron microscopy and diffractometry of materials

    CERN Document Server

    Fultz, Brent

    2001-01-01

    This book teaches graduate students the concepts of trans- mission electron microscopy (TEM) and x-ray diffractometry (XRD) that are important for the characterization of materi- als. It emphasizes themes common to both techniques, such as scattering from atoms and the formation and analysis of dif- fraction patterns. It also describes unique aspects of each technique, especially imaging and spectroscopy in the TEM. The textbook thoroughly develops both introductory and ad- vanced-level material, using over 400 accompanying illustra- tions. Problems are provided at the end of each chapter to reinforce key concepts. Simple citatioins of rules are avoi- ded as much as possible, and both practical and theoretical issues are explained in detail. The book can be used as both an introductory and advanced-level graduate text since sec- tions/chapters are sorted according to difficulty and grou- ped for use in quarter and semester courses on TEM and XRD.

  13. Coordinated Isotopic and TEM Studies of Presolar Graphites from Murchison

    Science.gov (United States)

    Croat, T. K.; Stadermann, F. J.; Zinner, E.; Bernatowicz, T. J.

    2004-03-01

    TEM and NanoSIMS investigations of the same presolar Murchison KFC graphites revealed high Zr, Mo, and Ru content in refractory carbides within the graphites. Along with isotopically light carbon, these suggest a low-metallicity AGB source.

  14. NPP Multi-Biome: TEM Calibration Data, 1992, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains one data file (.csv format) that is known as the Terrestrial Ecosystem Model (TEM) data set. The data provide pool sizes and fluxes of carbon...

  15. NPP Multi-Biome: TEM Calibration Data, 1992, R1

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains one data file (.csv format) that is known as the Terrestrial Ecosystem Model (TEM) data set. The data provide pool sizes and fluxes...

  16. Preparation of carbon-free TEM microgrids by metal sputtering.

    Science.gov (United States)

    Janbroers, S; de Kruijff, T R; Xu, Q; Kooyman, P J; Zandbergen, H W

    2009-08-01

    A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a 'holey' microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the 'same' microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775K under vacuum conditions.

  17. Comparison of ultramicrotomy and focused-ion-beam for the preparation of TEM and STEM cross section of organic solar cells

    DEFF Research Database (Denmark)

    Corazza, Michael; Simonsen, Søren Bredmose; Gnaegi, Helmut

    2016-01-01

    resolution, enabling further studies of phase separation of P3HT:PCBM by means of energy filtered TEM (EFTEM). The sample prepared by FIB shows good structure preservation, but reduced resolution due to non-optimal thicknesses achieved after treatment. Degradation studies of samples prepared......The challenge of preparing cross sections of organic photovoltaics (OPV) suitable for transmission electron microscopy (TEM) and scanning TEM (STEM) is addressed. The samples were polymer solar cells fabricated using roll-to-roll (R2R) processing methods on a flexible polyethylene terephthalate...

  18. Implementation of a Light Source in a TEM Sample Holder for In-situ Studies of Photocatalytic Materials

    DEFF Research Database (Denmark)

    Cavalca, Filippo; Hansen, Thomas Willum; Wagner, Jakob Birkedal

    Photocatalysts are of fundamental interest for sustainable energy research [1]. By means of transmission electron microscopy (TEM) it is possible to obtain insight into the structure, composition and reactivity of photocatalysts. Such insight can be used for their further optimization [2]. We have...... can be used inside an environmental TEM (ETEM) allowing specimens to be analyzed during exposure to a controlled gas atmosphere and illumination. The holder is presently being used to study a variety of photoreactive materials and structures, including photocatalysts, photonic devices and solar cells...... constructed a specimen holder capable of shining light onto samples inside the TEM. The holder contains a laser diode and an optical system that guides light onto a sample with maximum power transmission. The source can be changed and tuned, in principle spanning the whole visible and UV spectrum. The device...

  19. Transmission Electron Microscopy and Diffractometry of Materials (Third Edition)

    OpenAIRE

    Fultz, Brent; Howe, James M.

    2007-01-01

    This book explains concepts of transmission electron microscopy (TEM) and x-ray diffractometry (XRD) that are important for the characterization of materials. The third edition has been updated to cover important technical developments, including the remarkable recent improvement in resolution of the TEM. This edition is not substantially longer than the second, but all chapters have been updated and revised for clarity. A new chapter on high resolution STEM methods has been added. The book e...

  20. An automatic algorithm for determination of the nanoparticles from TEM images using circular hough transform.

    Science.gov (United States)

    Mirzaei, Mohsen; Rafsanjani, Hossein Khodabakhshi

    2017-05-01

    Nanoparticles have a wide range of applications in science and technology, and the size distribution of nanoparticles is one of the most important statistical properties. Transmission electron microscopy (TEM) or X-ray diffraction is commonly used for the characterization and measuring particle size distributions, but manual analysis of the micrographs is extremely labor-intensive. Here, we have developed an image processing algorithm for measuring particle size distributions from TEM images in the presence of overlapped particles and uneven background. The approach is based on the modified circular Hough transform, and pre and post processing techniques on TEM image to improve the accuracy and increase the detection rate of the nano particles. Its application is presented through several images with different noises, uneven backgrounds and over lapped particles. The merits of this robust quantifying method are demonstrated by comparing the results with the data obtained through manual measurement. The algorithm allows particles to be detected and characterized with high accuracy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The approaches to thin film preparation and TEM observations on slurry Si-modified aluminide coatings

    Energy Technology Data Exchange (ETDEWEB)

    Shirvani, K. [Materials Eng. Group, Department of Design and Manufacturing, New Technologies Institute, Iranian Research Organization for Science and Technology, Tehran 18815-3538 (Iran); Saremi, M. [Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Tehran, North Amirabad, Tehran (Iran); Yamamoto, Y. [Department of Metallurgy and Ceramics Science, Graduate School of Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2006-02-15

    Transmission electron microscopy (TEM) can be used as a precision characterization tool to identify very small precipitates in diffusion aluminide coatings. However, in order to successfully prepare the appropriate samples for TEM observation, often non-traditional thin film preparation techniques need to be employed. In this work, two sample preparation methods of twin jet electro-polishing and ion milling were experienced to characterize fine precipitates (< 1 {mu}m), in Si-aluminide coatings applied on Ni-base superalloy In-738LC by slurry technique. These precipitates are concentrated throughout the topcoat zone. It was found that the preparation of thin film exactly from the outer zone of the coating is only possible using ion milling process. The ion-milled specimens were utilized to observe by JEOL high resolution TEM operating at an accelerating voltage of 300 kV. Electron diffraction patterns, bright field and EDS were used to identify the precipitate phases as well as the coating matrix. The results showed that the fine precipitates are typically chromium silicides in nature, mostly as Cr{sub 3}Si and CrSi, distributed in the {beta}-NiAl matrix phase. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  2. Microstructure of organic–inorganic composite coatings studied by TEM and XANES

    Directory of Open Access Journals (Sweden)

    Etsuo Hamada, Masayasu Nagoshi, Kaoru Sato, Akira Matsuzaki, Takafumi Yamaji and Kotaro Kuroda

    2003-01-01

    Full Text Available Chromate coatings on Zn or Zn alloy coated steel sheets often include silica for the aim to improve corrosion resistance. In the case of dry-in-place chromate coatings containing acrylic resin (hereafter referred to as an organic–inorganic composite coating, an addition of silica, however, did not show an improvement in corrosion resistance. The microstructures of the organic–inorganic composite coatings were observed by transmission electron microscopy (TEM and the chemical states of Cr were investigated by the total electron yield X-ray absorption near edge structure (TEY-XANES method. TEM samples were successfully prepared by dry ultramicrotomy preventing water-soluble components in the coatings from dissolving out. TEY-XANES revealed the chemical states of components even in the organic matrix. Using these methods, it was found that the addition of silica changed just the morphology of the chromium compound in the organic–inorganic composite coating but not the chemical state of Cr. This is a reason for the addition of silica being not effective at improving corrosion resistance. The combination of dry ultramicrotomy-TEM and TEY-XANES spectroscopy was proven to be a powerful tool for characterizing organic–inorganic composite coatings.

  3. In Situ TEM Multi-Beam Ion Irradiation as a Technique for Elucidating Synergistic Radiation Effects

    Directory of Open Access Journals (Sweden)

    Caitlin Anne Taylor

    2017-09-01

    Full Text Available Materials designed for nuclear reactors undergo microstructural changes resulting from a combination of several environmental factors, including neutron irradiation damage, gas accumulation and elevated temperatures. Typical ion beam irradiation experiments designed for simulating a neutron irradiation environment involve irradiating the sample with a single ion beam and subsequent characterization of the resulting microstructure, often by transmission electron microscopy (TEM. This method does not allow for examination of microstructural effects due to simultaneous gas accumulation and displacement cascade damage, which occurs in a reactor. Sandia’s in situ ion irradiation TEM (I3TEM offers the unique ability to observe microstructural changes due to irradiation damage caused by concurrent multi-beam ion irradiation in real time. This allows for time-dependent microstructure analysis. A plethora of additional in situ stages can be coupled with these experiments, e.g., for more accurately simulating defect kinetics at elevated reactor temperatures. This work outlines experiments showing synergistic effects in Au using in situ ion irradiation with various combinations of helium, deuterium and Au ions, as well as some initial work on materials utilized in tritium-producing burnable absorber rods (TPBARs: zirconium alloys and LiAlO2.

  4. TEM nano-Moiré evaluation for an invisible lattice structure near the grain interface.

    Science.gov (United States)

    Zhang, Hongye; Wen, Huihui; Liu, Zhanwei; Zhang, Qi; Xie, Huimin

    2017-10-26

    Moiré technique is a powerful, important and effective tool for scientific research, from the nano-scale to the macro-scale, which is essentially the interference between two or more periodic structures with a similar frequency. In this study, an inverse transmission electron microscopy (TEM) nano-Moiré method has been proposed, for the first time, to reconstruct an invisible lattice structure near the grain interface, where only one kind of lattice structure and Moiré fringe were visible in a high resolution TEM (HRTEM) image simultaneously. The inversion process was performed in detail. Three rules were put forward to ensure the uniqueness of the inversion result. The HRTEM image of a top-coat/thermally grown oxide interface in a thermal barrier coating (TBC) structure was observed with coexisting visible lattice and Moiré fringes. Using the inverse TEM nano-Moiré method, the invisible lower layer lattice was inversed and a 3-dimensional structure near the interface was also reconstructed to some degree. The real strain field of oriented invisible and visible lattices and the relative strain field of the Moiré fringe in the grain and near the grain boundary were obtained simultaneously through the subset geometric phase analysis method. The possible failure mechanism and position of the TBC spallation from the nano-scale to the micro-scale were discussed.

  5. Synthesis, XRD, TEM, EPR, and Optical Absorption Spectral Studies of CuZnO2 Nanocompound

    Directory of Open Access Journals (Sweden)

    T. Ravindra Reddy

    2014-01-01

    Full Text Available Synthesis of nano CuZnO2 compound is carried out by thermal decomposition method. The crystalline phase of the material is characterized by XRD. The calculated unit cell constants are a=3.1 Å and c=3.4786 Å and are of tetragonal structure. The unit cell constants are different from wurtzite (hexagonal which indicate that a nanocompound is formed. Further TEM images reveal that the metal ion is in tetragonal structure with oxygen ligands. The prepared CuZnO2 is then characterized for crystallite size analysis by employing transmission electron microscopy (TEM. The size is found to be 100 nm. Uniform bright rings are noticed in the TEM picture suggesting that the nanocrystals have preferential instead of random orientations. The selected-area electron diffraction (SAED pattern clearly indicates the formation of CuO-ZnO nanocompound. The nature of bonding is studied by electron paramagnetic resonance (EPR. The covalency character is about 0.74 and thus the compound is electrically less conductive. Optical absorption spectral studies suggest that Cu(II is placed in tetragonal elongation crystal field. The spin-orbit coupling constant, λ, is calculated using the EPR and optical absorption spectral results suggest some covalent bond between metal and ligand. Near infrared (NIR spectra are due to hydroxyl and water fundamentals.

  6. Transmission Electron Microscopy Specimen Preparation Method for Multiphase Porous Functional Ceramics

    DEFF Research Database (Denmark)

    Zhang, Wei; Kuhn, Luise Theil; Jørgensen, Peter Stanley

    2013-01-01

    by successful preparation of TEM specimens that maintain the structural integrity of the entire lamella. Feasibility of the TEM alignment procedure is demonstrated, and ideal TEM analyses are illustrated on solid oxide fuel cell and solid oxide electrolysis cell materials. Some potential drawbacks of the TEM......An optimum method is proposed to prepare thin foil transmission electron microscopy (TEM) lamellae of multiphase porous functional ceramics: prefilling the pore space of these materials with an epoxy resin prior to focused ion beam milling. Several advantages of epoxy impregnation are demonstrated...

  7. Chapter 14: Electron Microscopy on Thin Films for Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Abou-Ras, Daniel [Helmholtz-Zentrum Berlin fur Materialien und Energie GmbH (HZB); Nichterwitz, Melanie [Helmholtz-Zentrum Berlin fur Materialien und Energie GmbH (HZB); Schmidt, Sebastian S. [Helmholtz-Zentrum Berlin fur Materialien und Energie GmbH (HZB)

    2016-07-22

    This chapter overviews the various techniques applied in scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and highlights their possibilities and also limitations. It gives the various imaging and analysis techniques applied on a scanning electron microscope. The chapter shows that imaging is divided into that making use of secondary electrons (SEs) and of backscattered electrons (BSEs), resulting in different contrasts in the images and thus providing information on compositions, microstructures, and surface potentials. Whenever aiming for imaging and analyses at scales of down to the angstroms range, TEM and its related techniques are appropriate tools. In many cases, also SEM techniques provide the access to various material properties of the individual layers, not requiring specimen preparation as time consuming as TEM techniques. Finally, the chapter dedicates to cross-sectional specimen preparation for electron microscopy. The preparation decides indeed on the quality of imaging and analyses.

  8. Determination of the activation energy in a cast aluminium alloy by TEM and DSC

    Energy Technology Data Exchange (ETDEWEB)

    Ovono Ovono, D. [Laboratoire Roberval, University of Technology of Compiegne, 60205 Compiegne (France)]. E-mail: delavand.ovono-ovono@utc.fr; Guillot, I. [Centre d' Etudes de Chimie Metallurgie, UPR2801 CNRS, 94407 Vitry-sur-Seine (France); Massinon, D. [Fonderie Montupet, 60181 Nogent-sur-Oise (France)

    2007-04-25

    The precipitation behaviour and microstructure development of the A319 alloy during ageing were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM and STEM). During T5 treatment, {theta}' precipitates with an average size of about 18 nm were observed by TEM. The precipitate sizes increased with ageing temperature and attained an average size of 107 nm. In addition, there was a linear relationship between precipitate growth temperature and the cube of the precipitate size. This indicates that precipitate growth of the A319 alloy belongs to a thermal activated process of the Arrhenius type. The activation energy for the precipitate growth was calculated to be 140.4 {+-} 13.3 kJ/mol. However, under continuous heating conditions, the activation energy for the precipitate growth obtained by Kissinger plot was determined to be 119.5 {+-} 8.3 kJ/mol. Allowing for experimental error, both values are comparable and are related to the diffusion of Cu and/or Si in Al.

  9. Optimized pre-thinning procedures of ion-beam thinning for TEM sample preparation by magnetorheological polishing.

    Science.gov (United States)

    Luo, Hu; Yin, Shaohui; Zhang, Guanhua; Liu, Chunhui; Tang, Qingchun; Guo, Meijian

    2017-10-01

    Ion-beam-thinning is a well-established sample preparation technique for transmission electron microscopy (TEM), but tedious procedures and labor consuming pre-thinning could seriously reduce its efficiency. In this work, we present a simple pre-thinning technique by using magnetorheological (MR) polishing to replace manual lapping and dimpling, and demonstrate the successful preparation of electron-transparent single crystal silicon samples after MR polishing and single-sided ion milling. Dimples pre-thinned to less than 30 microns and with little mechanical surface damage were repeatedly produced under optimized MR polishing conditions. Samples pre-thinned by both MR polishing and traditional technique were ion-beam thinned from the rear side until perforation, and then observed by optical microscopy and TEM. The results show that the specimen pre-thinned by MR technique was free from dimpling related defects, which were still residual in sample pre-thinned by conventional technique. Nice high-resolution TEM images could be acquired after MR polishing and one side ion-thinning. MR polishing promises to be an adaptable and efficient method for pre-thinning in preparation of TEM specimens, especially for brittle ceramics. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Exploration of shallow subsurface resistivity structure using a portable TEM system: TEM-FAST prosystem; Kan`igata TEM ho sochi TEM-FAST prosystem ni yoru senbu hiteiko chosa

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Y.; Kumekawa, Y.; Takasugi, S. [GERD Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan)

    1997-05-27

    Discussions were given on effectiveness of the TEM-FAST ProSystem which is a portable TEM system developed recently for use in exploration of shallow subsurface resistivity. The system consists of a loop type antenna, the TEM-FAST as the main equipment, and a host computer, the host computer controlling the entire system. The system acquires transient response data in secondary induced magnetic fields lasting 4 {mu} sec to 1 m sec. The number of data is 5490 stacks in one measurement, and the data acquisition time is about three minutes. Measurements were carried out by using the TEM-FAST in the vicinity of a well, whose results were compared with those of electric logging, and discussions were given on them. Although the electric logging results had no data available for depths shallower than 35 m, the measurement results from the TEM-FAST were found highly harmonious with those of the electric logging. In addition, there were transmission and telephone lines in locations about 10 m away from the well during the measurement, but extremely high data quality was discovered. 6 refs., 7 figs., 1 tab.

  11. The limits of TEM and beyond - Video Vignette.

    Science.gov (United States)

    Meylemans, Diederik Vg; Hompes, Roel; Cunningham, Chris

    2018-01-10

    Transanal Endoscopic Microsurgery (TEM) has been shown to be safe and feasible for both benign and malignant lesions, which aren't amendable to colonoscopic resection.[1, 2] Nonetheless these can be challenging, especially for circumferential, low and high anteriorly located lesions above the peritoneal reflection. Complications such as peritoneal perforation can be managed by TEM and a 360° resection can be closed and heals with minimal stenosis, even after prior radiotherapy. These add to the benefits of TEM (minimally invasive procedure with low morbidity and mortality, short length of stay and improved organ preservation rate with adequate function)[3, 4]. However, compared to rectal resection, this comes with an increased risk of local recurrence and need for neo-adjuvant treatment to downsize and downstage the tumour. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  12. SOFC anode reduction studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Wagner, Jakob Birkedal; Hansen, Thomas Willum

    for studying these nanoscale structures, but only few SOFC studies have applied in situ TEM to observe the ceramic nanostructures in a reactive gas environment at elevated temperatures. The present contribution focuses on the reduction of an SOFC anode which is a necessary process to form the catalytically......The Solid Oxide Fuel Cell (SOFC) is a promising part of future energy approaches due to a relatively high energy conversion efficiency and low environmental pollution. SOFCs are typically composed of ceramic materials which are highly complex at the nanoscale. TEM is routinely applied ex situ...... active Ni surface before operating the fuel cells. The reduction process was followed in the TEM while exposing a NiO/YSZ (YSZ = Y2O3-stabilized ZrO2) model anode to H2 at T = 250-1000⁰C. Pure NiO was used in reference experiments. Previous studies have shown that the reduction of pure Ni...

  13. Effect of the Tem Mode on the kicker Impedance

    CERN Document Server

    Zannini, C; Vaccaro, VG

    2012-01-01

    The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of a luminosity upgrade of the LHC. The C-Magnet supports a transverse electromagnetic (TEM) mode due to the presence of two conductors. Due to the finite length of the structure this TEM mode affects the impedance below a certain frequency (when the penetration depth in the ferrite becomes comparable to the magnetic circuit length). A theoretical model was developed to take into account also the impedance contribution due to the TEM mode. The model is found to be in good agreement with CST 3D electromagnetic (EM) simulations. It allows for generic terminations in the longitudinal direction. An example of kicker is analyzed taking into account also the external cables.

  14. Developments in TEM Nanotomography of Calcium Silicate Hydrate

    KAUST Repository

    Taylor, Rae

    2015-04-01

    This investigation was designed to explore the possibility of using transmission electron microscope (TEM) tomography on cement-based systems gain a greater understanding of their nanostructure and pore network. The preliminary results show a clearly a well-defined pore network at the nanoscale, with pore size approximately 1.7-2.4 nm in diameter and spaced around 5-8 nm apart. A comparison of small angle X-ray scattering data with 2-D TEM images analyzed with the Fourier slice theorem documents an excellent structural correlation. © 2015 The American Ceramic Society.

  15. Correlated Light Microscopy and Electron Microscopy

    NARCIS (Netherlands)

    Sjollema, Klaas A.; Schnell, Ulrike; Kuipers, Jeroen; Kalicharan, Ruby; Giepmans, Ben N. G.; MullerReichert, T; Verkade, P

    2012-01-01

    Understanding where, when, and how biomolecules (inter)act is crucial to uncover fundamental mechanisms in cell biology. Recent developments in fluorescence light microscopy (FLM) allow protein imaging in living cells and at the near molecular level. However, fluorescence microscopy only reveals

  16. Quantitative TEM analysis of a hexagonal mesoporous silicate structure.

    Science.gov (United States)

    Hudson, S; Tanner, D A; Redington, W; Magner, E; Hodnett, K; Nakahara, S

    2006-08-07

    TEM analysis of mesoporous materials is generally undertaken to give qualitative results. Accurate quantitative analysis is demonstrated in this study. A systematic image analysis of a powder form of a hexagonal mesoporous material known as KIT-6 is conducted using a transmission electron microscope (TEM). Three types of image contrast typically appear in this material (a hexagonal honeycomb structure, wide and narrow parallel lines). The honeycomb face is used to characterise this material in terms of a conventional 2-D hexagonal structure and the d-spacings for the (100) and (110) planes are experimentally measured in varying focus conditions. A tilting experiment is conducted to determine how the angle of tilt affects the line spacing and their visibility. Tilting has very little effect on the line spacing, whereas it affects the visibility of both the wide and narrow lines by limiting an angle range of visibility. The hexagonal lattice structure parameter determined by TEM method is found to be approximately 7% lower than that calculated by low-angle X-ray diffraction. Thus we conclude that TEM data can be used to determine the geometry and dimensions of hexagonal mesoporous silica materials, with a small error in the hexagonal lattice parameter.

  17. Robotics Collaborative Technology Alliance (RCTA): Technical Exchange Meeting (TEM) 2015

    Science.gov (United States)

    2017-05-01

    Laboratory Hodnik Debra National Ground Intelligence Center Hudson Irwin US Army Research Laboratory Jentsch Florian University of Central Florida...ARL-CR-0814 ● MAY 2017 US Army Research Laboratory Robotics Collaborative Technology Alliance (RCTA): Technical Exchange Meeting...0814 ● MAY 2017 US Army Research Laboratory Robotics Collaborative Technology Alliance (RCTA): Technical Exchange Meeting (TEM) 2015 by

  18. Herbal Remedies And Their Adverse Effects In Tem Tribe Traditional ...

    African Journals Online (AJOL)

    In Africa, up to 80% of the population relies on herbal concoctions for their primarily health care. In Togo, western Africa, Tem tribe is a population with old knowledge of medicinal plants, however, still very little is known about their medical practices. The present study was conducted to access for the apprehension of ...

  19. TEM Microstructure and Chemical Composition of Transition Zone Between Steel Tube and An Inconel 625 Weld Overlay Coating Produced by CMT Method

    OpenAIRE

    Rozmus-Górnikowska M.; Blicharski M.

    2017-01-01

    The aim of this work was to investigate the microstructure and chemical composition of the transition zone between 16Mo3 steel and Inconel 625 weld overlay coating produced by the Cold Metal Transfer (CMT) method. Investigations were primarily carried out through transmission electron microscopy (TEM) on thin foils prepared by FIB (Focus Ion Beam).

  20. TEM Microstructure and Chemical Composition of Transition Zone Between Steel Tube and An Inconel 625 Weld Overlay Coating Produced by CMT Method

    Directory of Open Access Journals (Sweden)

    Rozmus-Górnikowska M.

    2017-06-01

    Full Text Available The aim of this work was to investigate the microstructure and chemical composition of the transition zone between 16Mo3 steel and Inconel 625 weld overlay coating produced by the Cold Metal Transfer (CMT method. Investigations were primarily carried out through transmission electron microscopy (TEM on thin foils prepared by FIB (Focus Ion Beam.

  1. Transmission Electron Microscopy of Minerals and Rocks

    Science.gov (United States)

    McLaren, Alex C.

    1991-04-01

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

  2. Investigation of C3S hydration mechanism by transmission electron microscope (TEM) with integrated Super-XTMEDS system.

    Science.gov (United States)

    Sakalli, Y; Trettin, R

    2017-07-01

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

  3. Towards a correlative approach for characterising single virus particles by transmission electron microscopy and nanoscale Raman spectroscopy.

    Science.gov (United States)

    Hermelink, A; Naumann, D; Piesker, J; Lasch, P; Laue, M; Hermann, P

    2017-04-10

    The morphology and structure of biological nanoparticles, such as viruses, can be efficiently analysed by transmission electron microscopy (TEM). To chemically characterise such nanoparticles in heterogeneous samples at the single particle level, we suggest tip-enhanced Raman spectroscopy (TERS) as a correlative method. Here we describe a TERS-compatible staining procedure for TEM which involves sample pre-scanning by TEM imaging, nanoparticle relocalisation by atomic force microscopy (AFM) followed by spectroscopic characterization of the virus nanoparticles using TERS. First successful correlative measurements are demonstrated on tobacco mosaic virus particles deposited on silicon-based TEM sample supports. In addition, the advantages and problems of this methodology are discussed.

  4. Collaboration at the Nanoscale: Exploring Viral Genetics with Electron Microscopy

    Science.gov (United States)

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

    2009-01-01

    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…

  5. 2D Inversion of Transient Electromagnetic Method (TEM)

    Science.gov (United States)

    Bortolozo, Cassiano Antonio; Luís Porsani, Jorge; Acácio Monteiro dos Santos, Fernando

    2017-04-01

    A new methodology was developed for 2D inversion of Transient Electromagnetic Method (TEM). The methodology consists in the elaboration of a set of routines in Matlab code for modeling and inversion of TEM data and the determination of the most efficient field array for the problem. In this research, the 2D TEM modeling uses the finite differences discretization. To solve the inversion problem, were applied an algorithm based on Marquardt technique, also known as Ridge Regression. The algorithm is stable and efficient and it is widely used in geoelectrical inversion problems. The main advantage of 1D survey is the rapid data acquisition in a large area, but in regions with two-dimensional structures or that need more details, is essential to use two-dimensional interpretation methodologies. For an efficient field acquisition we used in an innovative form the fixed-loop array, with a square transmitter loop (200m x 200m) and 25m spacing between the sounding points. The TEM surveys were conducted only inside the transmitter loop, in order to not deal with negative apparent resistivity values. Although it is possible to model the negative values, it makes the inversion convergence more difficult. Therefore the methodology described above has been developed in order to achieve maximum optimization of data acquisition. Since it is necessary only one transmitter loop disposition in the surface for each series of soundings inside the loop. The algorithms were tested with synthetic data and the results were essential to the interpretation of the results with real data and will be useful in future situations. With the inversion of the real data acquired over the Paraná Sedimentary Basin (PSB) was successful realized a 2D TEM inversion. The results indicate a robust geoelectrical characterization for the sedimentary and crystalline aquifers in the PSB. Therefore, using a new and relevant approach for 2D TEM inversion, this research effectively contributed to map the most

  6. In situ TEM investigation of microstructural behavior of superplastic Al–Mg–Sc alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dám, Karel, E-mail: damk@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6 (Czech Republic); Institute of Physics of the ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Lejček, Pavel, E-mail: lejcekp@fzu.cz [Institute of Physics of the ASCR, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Michalcová, Alena [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technická 5, 166 28 Prague 6 (Czech Republic)

    2013-02-15

    Dynamic changes in microstructure of the superplastic ultrafine-grained Al–3Mg–0.2Sc (wt.%) alloy refined by equal-channel angular pressing (ECAP). were observed by in situ transmission electron microscopy at temperatures up to 300 °C (annealing and tensile deformation) in order to simulate the initial stages of superplastic testing. It was found that the microstructure changes significantly during the preheating before the superplastic deformation, which was accompanied by decreased microhardness. During the deformation at 300 °C, high dislocation activity as well as motion of low-angle grain boundaries was observed while high-angle grain boundaries did not move due to the presence of scandium in the alloy. - Highlights: ► We performed in situ TEM annealing and straining on superplastic Al–Mg–Sc alloy. ► We simulated the conditions of early stages of superplastic testing. ► Significant changes in microstructure occur during preheating before deformation.

  7. TEM characterization of organic nanocrystals grown in sol-gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Monnier, Virginie; Bacia, Maria [CNRS and Universite Joseph Fourier, Institut Neel (France); Putaux, Jean-Luc [ICMG-CNRS, Centre de Recherches sur les Macromolecules Vegetales (France); Ibanez, Alain [CNRS and Universite Joseph Fourier, Institut Neel (France)], E-mail: alain.ibanez@grenoble.cnrs.fr

    2008-01-15

    The tetracene molecule (2,3-benzanthracene, C{sub 8}H{sub 12}) was used to synthesize nanocrystals grown in sol-gel thin films, ranging from 10 to 100 nm of diameter. This confined nucleation and growth was compared to microcrystallizations of the same molecule in free solution. Transmission electron microscopy (TEM) was used to characterize these two kinds of tetracene crystals. The observation was performed under low-dose illumination to avoid amorphization of the samples during electron irradiation. Spatial confinement and size distribution of micro- and nanocrystals were compared. Using electron microdiffraction and diffraction patterns simulations, we showed that free microcrystals and nanocrystals confined in gel glasses exhibit the same triclinic P-bar 1 structure. In addition, time-resolved spectroscopy was used to record fluorescence decays, showing a monoexponential fluorescence decay for nanocrystals while microcrystals exhibit a multiexponential decay. The simple signature of nanocrystals luminescence is promising for the future development of chemical or biological sensors.

  8. Comparative IL-TEM study concerning the degradation of carbon supported Pt-based electrocatalysts

    DEFF Research Database (Denmark)

    Hartl, Katrin Gabriele; Hanzlik, Marianne; Arenz, Matthias

    2012-01-01

    responsible for the Pt surface area loss of carbon supported electrocatalysts. It is demonstrated that seemingly similar catalysts can exhibit under identical treatment pronounced differences in their degradation behaviour. As a consequence individual steps in the synthesis of electrocatalysts can have......In the present work the identical location transmission electron microscopy (IL-TEM) approach is used for a comparative study of the degradation of several standard Pt-based electrocatalysts for low temperature proton conducting membrane fuel cells (PEMFCs). The paper discusses the mechanisms...... a distinct effect on the degradation mechanism even if the base chemicals and materials used in their synthesis are identical. This finding sheds new light in the much debated issue if crystallite migration and coalescence or Pt dissolution and re-deposition are mainly responsible for the Pt surface area...

  9. XRD, TEM, and thermal analysis of Arizona Ca-montmorillonites modified with didodecyldimethylammonium bromide.

    Science.gov (United States)

    Sun, Zhiming; Park, Yuri; Zheng, Shuilin; Ayoko, Godwin A; Frost, Ray L

    2013-10-15

    An Arizona SAz-2 calcium montmorillonite was modified by a typical dialkyl cationic surfactant (didodecyldimethylammonium bromide, abbreviated to DDDMA) through direct ion exchange. The obtained organoclays were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), high-resolution thermogravimetric analysis (HR-TG), and infrared emission spectroscopy (IES). The intercalation of surfactants greatly increased the basal spacing of the interlayers and the conformation arrangement of the loaded surfactant were assessed based on the XRD and TEM measurements. This work shows that the dialkyl surfactant can be directly intercalated into the montmorillonite without first undergoing Na(+) exchange. Moreover, the thermal stability of organoclays and the different arrangements of the surfactant molecules intercalated in the SAz-2 Ca-montmorillonite were determined by a combination of TG and IES techniques. The detailed conformational ordering of different intercalated surfactants under different conditions was also studied. The surfactant molecule DDDMA has proved to be thermally stable even at 400°C which indicates that the prepared organoclay is stable to significantly high temperatures. This study offers new insights into the structure and thermal stabilities of SAz-2 Ca-montmorillonite modified with DDDMA. The experimental results also confirm the potential applications of organic SAz-2 Ca-montmorillonites as adsorbents and polymer-clay nanocomposites. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. ERDA, RBS, TEM and SEM characterization of microstructural evolution in helium-implanted Hastelloy N alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jie [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049 (China); Bao, Liangman [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Huang, Hefei, E-mail: huanghefei@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li, Yan, E-mail: liyan@sinap.ac.cn [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Lei, Qiantao [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Deng, Qi [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Liu, Zhe; Yang, Guo [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049 (China); Shi, Liqun [Institute of Modern Physics, Fudan University, Shanghai 200433 (China)

    2017-05-15

    Hastelloy N alloy was implanted with 30 keV, 5 × 10{sup 16} ions/cm{sup 2} helium ions at room temperature, and subsequent annealed at 600 °C for 1 h and further annealed at 850 °C for 5 h in vacuum. Using elastic recoil detection analysis (ERDA) and transmission electron microscopy (TEM), the depth profiles of helium concentration and helium bubbles in helium-implanted Hastelloy N alloy were investigated, respectively. The diffusion of helium and molybdenum elements to surface occurred during the vacuum annealing at 850 °C (5 h). It was also observed that bubbles in molybdenum-enriched region were much larger in size than those in deeper region. In addition, it is worth noting that plenty of nano-holes can be observed on the surface of helium-implanted sample after high temperature annealing by scanning electron microscope (SEM). This observation provides the evidence for the occurrence of helium release, which can be also inferred from the results of ERDA and TEM analysis.

  11. Fabrication of thin TEM sample of ionic liquid for high-resolution ELNES measurements

    Energy Technology Data Exchange (ETDEWEB)

    Miyata, Tomohiro, E-mail: tomo-m@iis.u-tokyo.ac.jp; Mizoguchi, Teruyasu, E-mail: teru@iis.u-tokyo.ac.jp

    2017-07-15

    Investigation of the local structure, ionic and molecular behavior, and chemical reactions at high spatial resolutions in liquids has become increasingly important. Improvements in these areas help to develop efficient batteries and improve organic syntheses. Transmission electron microscopy (TEM) and scanning-TEM (STEM) have excellent spatial resolution, and the electron energy-loss near edge structure (ELNES) measured by the accompanied electron energy-loss spectroscopy (EELS) is effective to analyze the liquid local structure owing to reflecting the electronic density of states. In this study, we fabricate a liquid-layer-only sample with thickness of single to tens nanometers using an ionic liquid. Because the liquid film has a thickness much less than the inelastic mean free path (IMFP) of the electron beam, the fine structure of the C-K edge electron energy loss near edge structure (ELNES) can be measured with sufficient resolution to allow meaningful analysis. The ELNES spectrum from the thin liquid film has been interpreted using first principles ELNES calculations. - Highlights: • A fabrication method of thin liquid film samples for STEM-EELS observations is proposed. • The thickness of the fabricated thin liquid film is about 10 nm. • An ELNES is measured from the thin liquid with a high energy resolution. • The peaks of the ELNES are interpreted using first principles calculations.

  12. TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

    Directory of Open Access Journals (Sweden)

    Moukrane Dehmas

    2011-01-01

    Full Text Available Inconel 718 is widely used because of its ability to retain strength at up to 650∘C for long periods of time through coherent metastable  Ni3Nb precipitation associated with a smaller volume fraction of  Ni3Al precipitates. At very long ageing times at service temperature,  decomposes to the stable Ni3Nb phase. This latter phase is also present above the  solvus and is used for grain control during forging of alloy 718. While most works available on precipitation have been performed at temperatures below the  solvus, it appeared of interest to also investigate the case where phase precipitates directly from the fcc matrix free of  precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM. TEM observations confirmed the presence of rotation-ordered domains in plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

  13. TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates

    Energy Technology Data Exchange (ETDEWEB)

    Liliental-Weber, Z.; Ni, X.; Morkoc, H.

    2006-01-05

    Transmission electron microscopy (TEM) was used to study pendeo-epitaxial GaN layers grown on polar and non-polar 4H SiC substrates. The structural quality of the overgrown layers was evaluated using a number of TEM methods. Growth of pendeo-epitaxial layers on polar substrates leads to better structural quality of the overgrown areas, however edge-on dislocations are found at the meeting fronts of two wings. Some misorientation between the 'seed' area and wing area was detected by Convergent Beam Electron Diffraction. Growth of pendeo-epitaxial layers on non-polar substrates is more difficult. Two wings on the opposite site of the seed area grow in two different polar directions with different growth rates. Most dislocations in a wing grown with Ga polarity are 10 times wider than wings grown with N-polarity making coalescence of these layers difficult. Most dislocations in a wing grown with Ga polarity bend in a direction parallel to the substrate, but some of them also propagate to the sample surface. Stacking faults formed on the c-plane and prismatic plane occasionally were found. Some misorientation between the wings and seed was detected using Large Angle Convergent Beam Diffraction.

  14. Fabrication of thin TEM sample of ionic liquid for high-resolution ELNES measurements.

    Science.gov (United States)

    Miyata, Tomohiro; Mizoguchi, Teruyasu

    2017-07-01

    Investigation of the local structure, ionic and molecular behavior, and chemical reactions at high spatial resolutions in liquids has become increasingly important. Improvements in these areas help to develop efficient batteries and improve organic syntheses. Transmission electron microscopy (TEM) and scanning-TEM (STEM) have excellent spatial resolution, and the electron energy-loss near edge structure (ELNES) measured by the accompanied electron energy-loss spectroscopy (EELS) is effective to analyze the liquid local structure owing to reflecting the electronic density of states. In this study, we fabricate a liquid-layer-only sample with thickness of single to tens nanometers using an ionic liquid. Because the liquid film has a thickness much less than the inelastic mean free path (IMFP) of the electron beam, the fine structure of the C-K edge electron energy loss near edge structure (ELNES) can be measured with sufficient resolution to allow meaningful analysis. The ELNES spectrum from the thin liquid film has been interpreted using first principles ELNES calculations. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Stereo-vision three-dimensional reconstruction of curvilinear structures imaged with a TEM.

    Science.gov (United States)

    Oveisi, Emad; Letouzey, Antoine; De Zanet, Sandro; Lucas, Guillaume; Cantoni, Marco; Fua, Pascal; Hébert, Cécile

    2018-01-01

    Deriving accurate three-dimensional (3-D) structural information of materials at the nanometre level is often crucial for understanding their properties. Tomography in transmission electron microscopy (TEM) is a powerful technique that provides such information. It is however demanding and sometimes inapplicable, as it requires the acquisition of multiple images within a large tilt arc and hence prolonged exposure to electrons. In some cases, prior knowledge about the structure can tremendously simplify the 3-D reconstruction if incorporated adequately. Here, a novel algorithm is presented that is able to produce a full 3-D reconstruction of curvilinear structures from stereo pair of TEM images acquired within a small tilt range that spans from only a few to tens of degrees. Reliability of the algorithm is demonstrated through reconstruction of a model 3-D object from its simulated projections, and is compared with that of conventional tomography. This method is experimentally demonstrated for the 3-D visualization of dislocation arrangements in a deformed metallic micro-pillar. Copyright © 2017. Published by Elsevier B.V.

  16. In-situ TEM on the coalescence of birnessite manganese dioxides nanosheets during lithiation process

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Ke [School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Kuang, Min; Zhang, Yuxin [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Liu, Jiabin, E-mail: liujiabin@zju.edu.cn [School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Wang, Hongtao, E-mail: htw@zju.edu.cn [Institute of Applied Mechanics, Zhejiang University, Hangzhou 310027 (China); Meng, Liang [School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2016-07-15

    Highlights: • Evolution of MnO{sub 2} nanosheets during lithiation was in situ observed. • MnO{sub 2} was reacted with Li to form Mn and LiO{sub 2}. • Nanosheets expanded and aggregated due to lithiation. - Abstract: Nanostructure is believed to produce great benefits for anode materials in lithium ion batteries (LIBs) by enhancing lithium ion transfer, accommodating large volume change and increasing surface area. Whether the nanostructure (especially the porous nanostructure) could be well held during charging/discharging process is one of the most commonly concerned issues in LIBs research. The dynamic evolution of birnessite manganese dioxides nanosheets during lithiation process is investigated by in-situ transmission electron microscopy (TEM) for the first time. The TiO{sub 2}@MnO{sub 2} core-shell nanowires are used as the anode and Li metal as the counter electrode inside the TEM. Interestingly, the lithiation process is confirmed as MnO{sub 2} and Li converting to Li{sub 2}O and Mn. The original porous structure of the nanosheets is hard to preserve during lithiation process due to lithiation-induced contact flattening.

  17. In Situ TEM Study of Interaction between Dislocations and a Single Nanotwin under Nanoindentation.

    Science.gov (United States)

    Wang, Bo; Zhang, Zhenyu; Cui, Junfeng; Jiang, Nan; Lyu, Jilei; Chen, Guoxin; Wang, Jia; Liu, Zhiduo; Yu, Jinhong; Lin, Chengte; Ye, Fei; Guo, Dongming

    2017-09-06

    Nanotwinned (nt) materials exhibit excellent mechanical properties, and have been attracting much more attention of late. Nevertheless, the fundamental mechanism of interaction between dislocations and a single nanotwin is not understood. In this study, in situ transmission electron microscopy (TEM) nanoindentation is performed, on a specimen of a nickel (Ni) alloy containing a single nanotwin of 89 nm in thickness. The specimen is prepared using focused ion beam (FIB) technique from an nt surface, which is formed by a novel approach under indentation using a developed diamond panel with tips array. The stiffness of the specimen is ten times that of the pristine counterparts during loading. The ultrahigh stiffness is attributed to the generation of nanotwins and the impediment of the single twin to the dislocations. Two peak loads are induced by the activation of a new slip system and the penetration of dislocations over the single nanotwin, respectively. One slip band is parallel to the single nanotwin, indicating the slip of dislocations along the nanotwin. In situ TEM observation of nanoindentation reveals a new insight for the interaction between dislocations and a single nanotwin. This paves the way for design and preparation of high-performance nt surfaces of Ni alloys used for aircraft engines, gas turbines, turbocharger components, ducts, and absorbers.

  18. LDRD Final Report - In Operando Liquid Cell TEM Characterization of Nickel-Based Electrocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-11-07

    A commercial electrochemistry stage for transmission electron microscopy (TEM) was tested to determine whether to purchase one for the microscopes at Lawrence Livermore National Lab (LLNL). Deposition of a nickel-based electrocatalyst was pursued as a material system for the purpose of testing the stage. The stage was found to be problematic with recurring issues in the electrical connections and vacuum sealing, which has thus far precluded a systematic investigation of the original material system. However, the electrochemical cells purchased through this FS will allow the Lawrence Fellow (Nielsen) to continue testing the stage. Furthermore, discussions with a second vendor, which released a similar electrochemical TEM stage during the course of this FS, have resulted in an upcoming longterm loan of their stage at Lawrence Berkeley National Lab (LBNL) for testing. In addition, low-loss electron energy-loss spectroscopy (EELS) measurements on nickel-bearing electrolyte solutions led to a broader EELS investigation of solvents and salt solutions. These measurements form the basis of a manuscript in preparation on EELS measurements of the liquid phase.

  19. TEM, SEM, and X-ray analysis of Cu-Ni alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Carreras, A.C. [Universidad Nacional de Cordoba, Cordoba, Cba (Argentina); Cangiano, M. de los A.; Ojeda, M.W.; Ruiz, M. del C. [Universidad Nacional de San Luis, San Luis (Argentina)

    2012-07-01

    Full text: Cu-Ni alloys are extensively used in several metallurgical industries. The traditional methods for the synthesis of these alloys have some limitations, mainly related with manufacturing costs and with the homogeneity of the final product, which encourages the study and development of new methodologies to produce them. In our research group we have developed a new chemical route for the synthesis of Cu-Ni alloys [1,2]. The process involves four steps, including the precursor preparation by the citrate-gel method and the subsequent decomposition, calcination and reduction. In this work, the physicochemical characterization of Cu-Ni alloy nanoparticles synthesized by the new chemical route is presented. The sample characterization was performed by means of Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Ray Diffraction (XRD). The results of TEM and EDS analyses showed that Cu-Ni alloy nanoparticles with a good chemical homogeneity were obtained. The mean Cu/Ni atomic ratio was around 0.98. The XRD diagram showed the formation of a new phase with intermediate lattice parameter between the corresponding to pure Cu and Ni structures, and with an average grain size around 6 nm. The chemical homogeneity of the alloy obtained is discussed on the basis of the resolution of the analytical techniques used. [1] M. de los A. Cangiano, A. C. Carreras, M. W. Ojeda and M. del C. Ruiz, A new chemical route to synthesize Cu-Ni alloy nanostructured particles. Journal of Alloys and Compounds, 458 (2008) 405-409. [2] M. de los A. Cangiano, M. W. Ojeda, A. C. Carreras, J. A. Gonzalez and M. del C. Ruiz, A study of the composition and microstructure of nanodispersed Cu-Ni alloy obtained by different routes from copper and nickel oxides. Materials Characterization, 61 (2010) 1135-1146. (author)

  20. In-depth TEM characterization of block copolymer pattern transfer at germanium surfaces

    Science.gov (United States)

    Cummins, Cian; Collins, Timothy W.; Kelly, Roisin A.; McCarthy, Eoin K.; Morris, Michael A.

    2016-12-01

    Dry plasma etching for the pattern transfer of mask features is fundamental to semiconductor processing and the development of device and electrically conducting elements becomes more challenging as features reach the deep nanoscale regime. In this work, high resolution transmission electron microscopy (TEM) coupled with energy dispersive x-ray (EDX) characterization were used to analyze the pattern transfer of graphoepitaxially aligned block copolymer (BCP) features to germanium (Ge) substrates as a function of time. The BCP patterns were converted into metal oxide hardmasks in order to affect good aspect ratios of the transferred features. An unusual interface layer between metal oxide nanowires and the germanium-on-insulator substrate was observed. EDX analysis shows that the origin of this interface layer is a result of the presence of a negative tone e-beam resist material, HSQ (hydrogen silsesquioxane). HSQ was employed as a guiding material to align line-space features of poly(styrene)-block-poly(4-vinylpyridine) (PS-b-P4VP) BCP with 16 nm half-pitch topography. Additionally, the existence of a metal oxide layer (from the initial PS-b-P4VP film) is also shown through ex situ TEM and EDX characterization. Three dimensional modeling of features is also provided giving a unique insight into the arrangement and structure of BCP features prior to and after the pattern transfer process. The results presented in this article highlight the accuracy of high resolution electron microscopy and elemental mapping of BCP generated on-chip etch masks to observe and understand through-film features affecting pattern transfer.

  1. Introduction to fluorescence microscopy.

    Science.gov (United States)

    Ghiran, Ionita C

    2011-01-01

    This chapter is an overview of basic principles of fluorescence microscopy, including a brief history on the invention of this type of microscopy. The chapter highlights important points related to properties of fluorochromes, resolution in fluorescence microscopy, phase contrast and fluorescence, fluorescence filters, construction of a fluorescence microscope, and tips on the correct use of this equipment.

  2. A developed wedge fixtures assisted high precision TEM samples pre-thinning method: Towards the batch lamella preparation

    Science.gov (United States)

    Wang, Dandan; Huang, Yamin; Liu, Binghai; Zhu, Lei; Lam, Jeffrey; Mai, Zhihong

    2017-04-01

    Ion milling, wedge cutting or polishing, and focused ion beam (FIB) milling are widely-used techniques for the transmission electron microscope (TEM) sample preparation. Especially, the FIB milling provides a site-specific analysis, deposition, and ablation of materials in the micrometer and nanometer scale. However, the cost of FIB tools has been always a significant concern. Since it is inevitable to use the FIB technique, the improvement of efficiency is a key point. Traditional TEM sample preparation with FIB was routinely implemented on a single sample each time. Aiming at cost efficiency, a new pre-thinning technique for batch sample preparation was developed in this paper. The present proposal combines the sample preparation techniques with multi-samples thinning, cross-section scanning electron microscopy (SEM), wedge cutting, FIB and other sample pre-thinning techniques. The new pre-thinning technique is to prepare an edge TEM sample on a grinding and polishing fixture with a slant surface. The thickness of the wedges sample can be measured to 1˜2 μm under optical microscope. Therefore, this fixture is superior to the traditional optical method of estimating the membrane thickness. Moreover, by utilizing a multi-sample holding fixture, more samples can be pre-thinned simultaneously, which significantly improved the productivity of TEM sample preparation.

  3. Practical workflow for cryo focused-ion-beam milling of tissues and cells for cryo-TEM tomography.

    Science.gov (United States)

    Hsieh, Chyongere; Schmelzer, Thomas; Kishchenko, Gregory; Wagenknecht, Terence; Marko, Michael

    2014-01-01

    Vitreous freezing offers a way to study cells and tissue in a near-native state by cryo-transmission electron microscopy (cryo-TEM), which is important when structural information at the macromolecular level is required. Many cells - especially those in tissue - are too thick to study intact in the cryo-TEM. Cryo focused-ion-beam (cryo-FIB) milling is being used in a few laboratories to thin vitreously frozen specimens, thus avoiding the artifacts and difficulties of cryo-ultramicrotomy. However, the technique is challenging because of the need to avoid devitrification and frost accumulation during the entire process, from the initial step of freezing to the final step of loading the specimen into the cryo-TEM. We present a robust workflow that makes use of custom fixtures and devices that can be used for high-pressure-frozen bulk tissue samples as well as for samples frozen on TEM grids. Copyright © 2013 Elsevier Inc. All rights reserved.

  4. A developed wedge fixtures assisted high precision TEM samples pre-thinning method: Towards the batch lamella preparation

    Directory of Open Access Journals (Sweden)

    Dandan Wang

    2017-04-01

    Full Text Available Ion milling, wedge cutting or polishing, and focused ion beam (FIB milling are widely-used techniques for the transmission electron microscope (TEM sample preparation. Especially, the FIB milling provides a site-specific analysis, deposition, and ablation of materials in the micrometer and nanometer scale. However, the cost of FIB tools has been always a significant concern. Since it is inevitable to use the FIB technique, the improvement of efficiency is a key point. Traditional TEM sample preparation with FIB was routinely implemented on a single sample each time. Aiming at cost efficiency, a new pre-thinning technique for batch sample preparation was developed in this paper. The present proposal combines the sample preparation techniques with multi-samples thinning, cross-section scanning electron microscopy (SEM, wedge cutting, FIB and other sample pre-thinning techniques. The new pre-thinning technique is to prepare an edge TEM sample on a grinding and polishing fixture with a slant surface. The thickness of the wedges sample can be measured to 1∼2 μm under optical microscope. Therefore, this fixture is superior to the traditional optical method of estimating the membrane thickness. Moreover, by utilizing a multi-sample holding fixture, more samples can be pre-thinned simultaneously, which significantly improved the productivity of TEM sample preparation.

  5. 4D electron microscopy: principles and applications.

    Science.gov (United States)

    Flannigan, David J; Zewail, Ahmed H

    2012-10-16

    The transmission electron microscope (TEM) is a powerful tool enabling the visualization of atoms with length scales smaller than the Bohr radius at a factor of only 20 larger than the relativistic electron wavelength of 2.5 pm at 200 keV. The ability to visualize matter at these scales in a TEM is largely due to the efforts made in correcting for the imperfections in the lens systems which introduce aberrations and ultimately limit the achievable spatial resolution. In addition to the progress made in increasing the spatial resolution, the TEM has become an all-in-one characterization tool. Indeed, most of the properties of a material can be directly mapped in the TEM, including the composition, structure, bonding, morphology, and defects. The scope of applications spans essentially all of the physical sciences and includes biology. Until recently, however, high resolution visualization of structural changes occurring on sub-millisecond time scales was not possible. In order to reach the ultrashort temporal domain within which fundamental atomic motions take place, while simultaneously retaining high spatial resolution, an entirely new approach from that of millisecond-limited TEM cameras had to be conceived. As shown below, the approach is also different from that of nanosecond-limited TEM, whose resolution cannot offer the ultrafast regimes of dynamics. For this reason "ultrafast electron microscopy" is reserved for the field which is concerned with femtosecond to picosecond resolution capability of structural dynamics. In conventional TEMs, electrons are produced by heating a source or by applying a strong extraction field. Both methods result in the stochastic emission of electrons, with no control over temporal spacing or relative arrival time at the specimen. The timing issue can be overcome by exploiting the photoelectric effect and using pulsed lasers to generate precisely timed electron packets of ultrashort duration. The spatial and temporal resolutions

  6. Transmission Electron Microscopy and Diffractometry of Materials

    CERN Document Server

    Fultz, Brent

    2013-01-01

    This book explains concepts of transmission electron microscopy (TEM) and x-ray diffractometry (XRD) that are important for the characterization of materials. The fourth edition adds important new techniques of TEM such as electron tomography, nanobeam diffraction, and geometric phase analysis. A new chapter on neutron scattering completes the trio of x-ray, electron and neutron diffraction. All chapters were updated and revised for clarity. The book explains the fundamentals of how waves and wavefunctions interact with atoms in solids, and the similarities and differences of using x-rays, electrons, or neutrons for diffraction measurements. Diffraction effects of crystalline order, defects, and disorder in materials are explained in detail. Both practical and theoretical issues are covered. The book can be used in an introductory-level or advanced-level course, since sections are identified by difficulty. Each chapter includes a set of problems to illustrate principles, and the extensive Appendix includes la...

  7. Characterization of some biological specimens using TEM and SEM

    Science.gov (United States)

    Ghosh, Nabarun; Smith, Don W.

    2009-05-01

    The advent of novel techniques using the Transmission and Scanning Electron Microscopes improved observation on various biological specimens to characterize them. We studied some biological specimens using Transmission and Scanning Electron Microscopes. We followed negative staining technique with Phosphotungstic acid using bacterial culture of Bacillus subtilis. Negative staining is very convenient technique to view the structural morphology of different samples including bacteria, phage viruses and filaments in a cell. We could observe the bacterial cell wall and flagellum very well when trapped the negative stained biofilm from bacterial culture on a TEM grid. We cut ultra thin sections from the fixed root tips of Pisum sativum (Garden pea). Root tips were pre fixed with osmium tetroxide and post fixed with uranium acetate and placed in the BEEM capsule for block making. The ultrathin sections on the grid under TEM showed the granular chromatin in the nucleus. The protein bodies and large vacuoles with the storage materials were conspicuous. We followed fixation, critical point drying and sputter coating with gold to view the tissues with SEM after placing on stubs. SEM view of the leaf surface of a dangerous weed Tragia hispida showed the surface trichomes. These trichomes when break on touching releases poisonous content causing skin irritation. The cultured tissue from in vitro culture of Albizia lebbeck, a tree revealed the regenerative structures including leaf buds and stomata on the tissue surface. SEM and TEM allow investigating the minute details characteristic morphological features that can be used for classroom teaching.

  8. Stable numerical wave field transforms of TEM data

    Energy Technology Data Exchange (ETDEWEB)

    Slob, E.C. [Technische Univ. Delft (Netherlands); Habashy, T.M.; Torres-verdin, C. [Schlumberger-Doll Research Center, Ridgefield, CT (United States)

    1995-12-31

    Successful application of the wave field transform to diffusive electromagnetic (TEM) field data opens up the possibilities of processing the data with the well known seismic processing techniques. Since the time source functions used in field surveys are usually step-current switches, the fields in the wave field transform domain will be the response to a linear function, which is the q-domain equivalent source. Hence, the fields will in general be unbounded for large values of q and have delta-like and step-like discontinuities for those values of q that correspond to the arrivals of waves. It is exactly this correspondence principle that makes a numerical implementation of the transform very difficult. This consideration has recently led to a reformulation of the wave field transformation, where the q-domain field is convolved with a window function that is smooth function of q which has zero mean. The window function can be chosen freely as long as it has a zero mean. The convolved fields will then be smooth and vanish for large values of q. Hence, TEM data should be convolved with the time domain equivalent of the window function and then be transformed to the q-domain. Since we have control over the window function, we have a controlled convolution problem in the q-domain to find arrival times. Two numerical methods have been successfully tested, using the convolution, for single arrival data. Now we test it on more general TEM data. (author). 5 refs

  9. Direct Imaging by Cryo-TEM Shows Membrane Break-up by Phospholipase A2 Enzymatic Activity

    DEFF Research Database (Denmark)

    Callisen, Thomas Hønger; Talmon, Y.

    1998-01-01

    increase our insight into the function of PLA2 under physiological conditions as well as into general interfacial catalysis. In the present study we apply for the first time cryo-transmission electron microscopy (cryo-TEM) and high-performance liquid chromatography (HPLC) to characterize the PLA2...... hydrolysis of phospholipid vesicles with respect to changes in lipid composition and morphology. Our direct experimental results show that the initial reaction conditions are strongly perturbed during the course of hydrolysis, Most strikingly, cryo-TEM reveals that starting in the lag phase, vesicles become...... perforated and degrade into open vesicles, bilayer fragments, and micelles, This structural instability extends throughout the system in the activity burst regime. In agreement with earlier reported correlations between initial phospholipase activity and substrate morphology, our results suggest that the lag...

  10. Nanoscale clusters in the thermoelectric AgPbmSbTem+2 and AgnSnmSbnTem+2n materials

    Science.gov (United States)

    Lin, He; Bozin, Emil; Hoang, Khang; Mahanti, S. D.; Billinge, Simon; Quarez, Eric; Androula, John; Kanatzidis, Mercouri

    2006-03-01

    The local structure of the AgPbmSbTem+2 series of high performance thermoelectric materials has been studied using the atomic pair distribution function (PDF) method. The dimensionless thermoelectric figure of merit, ZT, of the m˜18 composition material was found to reach 1.7 at 700 kelvin, compared to the highest observed ZT of only 0.84 for PbTe at 648 kelvin in n-doped material. This is asurprisingly large enhancement in ZT for the addition of just 10%per formula-unit of silver and antimony ions. It is clearly of the greatest importance to trace the origin of the ZT enhancement. Three candidate-models were attempted for thestructure of this class of materials using either a one-phase or a two-phase modeling procedure. Combining modeling the PDF with HRTEM data we show that AgPbmSbTem+2 contains nanoscale inclusions with composition close to AgPb3SbTe5 randomly embedded in a PbTe matrix. We extended the local structural PDF study to AgnSnmSbnTem+2n, preliminary results of which suggest the presence of nanoscale inclusions in this system as well.

  11. Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

    Science.gov (United States)

    Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

    2014-12-01

    High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

  12. A toolkit for the characterization of CCD cameras for transmission electron microscopy

    NARCIS (Netherlands)

    Vulovic, M.; Rieger, B.; Van Vliet, L.J.; Koster, A.J.; Ravelli, R.B.G.

    2009-01-01

    Charge-coupled devices (CCD) are nowadays commonly utilized in transmission electron microscopy (TEM) for applications in life sciences. Direct access to digitized images has revolutionized the use of electron microscopy, sparking developments such as automated collection of tomographic data, focal

  13. Modeling of planar quasi-TEM superconducting transmission lines

    Science.gov (United States)

    Antsos, Dimitrios; Chew, Wilbert; Riley, A. L.; Hunt, Brian D.; Foote, Marc C.; Bajuk, Louis J.; Rascoe, Daniel L.; Cooley, Thomas W.

    1992-01-01

    An application of the phenomenological loss equivalence method (Lee and Itoh, 1989) in modeling the microwave behavior of planar quasi-TEM superconducting transmission lines is presented. For validation of the model, data are used from measurements of a YBCO superconducting thin-film coplanar-waveguide lowpass filter on a lanthanum aluminate substrate. Measured and modeled S-parameters of an existing superconducting coplanar waveguide lowpass filter agree to within 0.3 dB in magnitude and 0.5 radians in phase. Extracted values for penetration depth and real part of the conductivity of the superconducting film are within 10 percent of other researchers' findings.

  14. TEM Pump With External Heat Source And Sink

    Science.gov (United States)

    Nesmith, Bill J.

    1991-01-01

    Proposed thermoelectric/electromagnetic (TEM) pump driven by external source of heat and by two or more heat pipe radiator heat sink(s). Thermoelectrics generate electrical current to circulate liquid metal in secondary loop of two-fluid-loop system. Intended for use with space and terrestrial dual loop liquid metal nuclear reactors. Applications include spacecraft on long missions or terrestrial beacons or scientific instruments having to operate in remote areas for long times. Design modified to include multiple radiators, converters, and ducts, as dictated by particular application.

  15. Shear Punch Testing of BOR-60 Irradiated TEM Specimens

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Tarik A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Quintana, Matthew Estevan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Romero, Tobias J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-13

    As a part of the project “High Fidelity Ion Beam Simulation of High Dose Neutron Irradiation” an Integrated Research Program (IRP) project from the U.S. Department of Energy, Nuclear Energy University Programs (NEUP), TEM geometry samples of ferritic cladding alloys, Ni based super alloys and model alloys were irradiated in the BOR-60 reactor to ~16 dpa at ~370°C and ~400°C. Samples were sent to Los Alamos National Laboratory and subjected to shear punch testing. This report presents the results from this testing.

  16. In-situ TEM characterization of nanomaterials and devices

    KAUST Repository

    Kim, Moon

    2011-10-01

    Electrical properties of nano size devices were directly measured by TEM. Real time observation of phase transition behavior in PRAM revealed that the volume of the crystalline phase is the main factor in determining cell resistance. In the transistor device, we have identified the doping type and area by measuring the I-V curve at the individual nano contact on the specimen. The evolution of the graphene edge structure was controlled and monitored at and up to 1200°C in-situ. © 2011 IEEE.

  17. New microscopy for nanoimaging

    CERN Document Server

    Kinjo, Y; Watanabe, M

    2002-01-01

    Two types of new microscopy, namely, X-ray contact microscopy (XRCM) in combination with atomic force microscopy (AFM) and X-ray projection microscopy (XRPM) using synchrotron radiation and zone plate optics were used to image the fine structures of human chromosomes. In the XRCM plus AFM system, location of X-ray images on a photoresist has become far easier than that with our previous method using transmission electron microscopy coupled with the replica method. In addition, the images obtained suggested that the conformation of chromatin fiber differs from the current textbook model regarding the architecture of a eukaryotic chromosome. X-ray images with high contrast of the specimens could be obtained with XRPM. The resolution of each microscopy was about 30 and 200-300 nm for XRCM plus AFM and XRPM, respectively. (author)

  18. Scanning ultrafast electron microscopy

    OpenAIRE

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

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for whic...

  19. Fluorescence (Multiwave) Confocal Microscopy.

    Science.gov (United States)

    Welzel, J; Kästle, Raphaela; Sattler, Elke C

    2016-10-01

    In addition to reflectance confocal microscopy, multiwave confocal microscopes with different laser wavelengths in combination with exogenous fluorophores allow fluorescence mode confocal microscopy in vivo and ex vivo. Fluorescence mode confocal microscopy improves the contrast between the epithelium and the surrounding soft tissue and allows the depiction of certain structures, like epithelial tumors, nerves, and glands. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Development of an ultrafast electron source based on a cold-field emission gun for ultrafast coherent TEM

    Science.gov (United States)

    Caruso, Giuseppe Mario; Houdellier, Florent; Abeilhou, Pierre; Arbouet, Arnaud

    2017-07-01

    We report on the design of a femtosecond laser-driven electron source for ultrafast coherent transmission electron microscopy. The proposed architecture allows introducing an ultrafast laser beam inside the cold field emission source of a commercial TEM, aligning and focusing the laser spot on the apex of the nanoemitter. The modifications of the gun assembly do not deteriorate the performances of the electron source in conventional DC mode and allow easy switching between the conventional and ultrafast laser-driven emission modes. We describe here this ultrafast electron source and discuss its properties.

  1. Electron Microscopy Center (EMC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Electron Microscopy Center (EMC) at Argonne National Laboratory develops and maintains unique capabilities for electron beam characterization and applies those...

  2. Coherent light microscopy

    CERN Document Server

    Ferraro, Pietro; Zalevsky, Zeev

    2011-01-01

    This book deals with the latest achievements in the field of optical coherent microscopy. While many other books exist on microscopy and imaging, this book provides a unique resource dedicated solely to this subject. Similarly, many books describe applications of holography, interferometry and speckle to metrology but do not focus on their use for microscopy. The coherent light microscopy reference provided here does not focus on the experimental mechanics of such techniques but instead is meant to provide a users manual to illustrate the strengths and capabilities of developing techniques. Th

  3. Bridging fluorescence microscopy and electron microscopy

    NARCIS (Netherlands)

    Giepmans, Ben N. G.

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

  4. Application of TEM to characterize fly ash- and slag cements

    NARCIS (Netherlands)

    Pietersen, H.S.

    1999-01-01

    A Portland fly ash cement containing 20% of a fine fly ash and a blast furnace slag cement of approximately 290 days old were examined with analytical transmission electron microscopy, in order to examine the (local) microstructure in these cements in detail. In the Portland fly ash cement the fly

  5. A TEM Study on the Microstructure of Fine Flaky Graphite

    DEFF Research Database (Denmark)

    Moumeni, Elham; Tiedje, Niels Skat; Horsewell, Andy

    In this investigation the microstructure of the graphite flakes in titanium alloyed cast iron is studied using electron microscopy techniques. Based on this information, growth models for the platelets in the fine graphite flakes in cast iron are considered. Detailed crystallographic analysis...

  6. Electronic detectors for electron microscopy.

    Science.gov (United States)

    Faruqi, A R; McMullan, G

    2011-08-01

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

  7. Transmission electron microscopy investigation of Bi-2223/Ag tapes

    DEFF Research Database (Denmark)

    Andersen, L.G.; Bals, S.; Tendeloo, G. Van

    2001-01-01

    The microstructure of (Bi,Pb)(2)Sr2Ca2CuOx (Bi-2223) tapes has been investigated by means of transmission electron microscopy (TEM) and high-resolution TEM. The emphasis has been placed on: (1) an examination of the grain morphology and size, (2) grain and colony boundary angles, which are formed...... the first annealing. The angles of c-axis tilt grain boundaries are on average 14 degrees and 26 degrees for the fully processed tape and the tape after the first annealing, respectively. The intergrowth content(15%) and distribution are similar in these two tapes. (C) 2001 Elsevier Science B.V. All rights...

  8. Transmission electron microscopy of a model crystalline organic, theophylline

    Science.gov (United States)

    Cattle, J.; S'ari, M.; Hondow, N.; Abellán, P.; Brown, A. P.; Brydson, R. M. D.

    2015-10-01

    We report on the use of transmission electron microscopy (TEM) to analyse the diffraction patterns of the model crystalline organic theophylline to investigate beam damage in relation to changing accelerating voltage, sample temperature and TEM grid support films. We find that samples deposited on graphene film grids have the longest lifetimes when also held at -190 °C and imaged at 200 kV accelerating voltage. Finally, atomic lattice images are obtained in bright field STEM by working close to the estimated critical electron dose for theophylline.

  9. Laboratory Investigation of the Growth and Crystal Structure of Nitric Acid Hydrates by Transmission Electron Microscopy (TEM)

    Science.gov (United States)

    Blake, David F.; Chang, Sherwood (Technical Monitor)

    1994-01-01

    A great deal of recent laboratory work has focussed on the characterization of the nitric acid hydrates, thought to be present in type I Polar Stratospheric Clouds (PSCs). Phase relationships and vapor pressure measurements (1-3) and infrared characterizations (4-5) have been made. However, the observed properties of crystalline solids (composition, melting point, vapor pressure, surface reactivity, thermodynamic stability, extent of solid solution with other components, etc.) are controlled by their crystal structure. The only means of unequivocal structural identification for crystalline solids is diffraction (using electrons, X-rays, neutrons, etc.). Other observed properties of crystalline solids, such as their infrared spectra, their vapor pressure as a function of temperature, etc. yield only indirect information about what phases are present, their relative proportions, or whether they are crystalline or amorphous.

  10. Handbook of Microscopy for Nanotechnology

    Science.gov (United States)

    Yao, Nan; Wang, Zhong L.

    This handbook highlights various key microcopic techniques and their applications in this fast-growing field. Topics to be covered include the following: scanning near field optical microscopy, confocal optical microscopy, atomic force microscopy, magnetic force microscopy, scanning turning microscopy, high-resolution scanning electron microscopy, and many more.

  11. Tem Observation Of Age-Hardening Precipitation In Mg-Gd-Y Alloys As Different Gd/Y Ratio

    Directory of Open Access Journals (Sweden)

    Matsuoka Y.

    2015-06-01

    Full Text Available In this study, the early stage of aging in Mg-Gd-Y alloys has been observed by transmission electron microscopy (TEM, high angle annular dark field – scanning transmission electron microscopy (HAADF-STEM and calculations of images and electron density and bond overlap population (BOP by first principal to understand the origin of precipitation in this alloy. The small hexagon of 0.37 nm is the first precipitate in this alloy, and this is the evidence of short range ordering of D019 structure. This is referred as the pre β”-phase. In the peak aged condition, β’ phase with bco structure was mainly observed.

  12. Thin dielectric film thickness determination by advanced transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-09-01

    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.

  13. LEDs for fluorescence microscopy

    NARCIS (Netherlands)

    Young, I.T.; Garini, Y.; Dietrich, H.R.C.; Van Oel, W.; Liqui Lung, G.

    2004-01-01

    Traditional light sources for fluorescence microscopy have been mercury lamps, xenon lamps, and lasers. These sources have been essential in the development of fluorescence microscopy but each can have serious disadvantages: lack of near monochromaticity, heat generation, cost, lifetime of the light

  14. Lasers for nonlinear microscopy.

    Science.gov (United States)

    Wise, Frank

    2013-03-01

    Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.

  15. Cryo-electron microscopy of vitreous sections.

    Science.gov (United States)

    Chlanda, Petr; Sachse, Martin

    2014-01-01

    More than 30 years ago two groups independently reported the vitrification of pure water, which was until then regarded as impossible without a cryoprotectant [1, 2]. This opened the opportunity to cryo-electron microscopy (cryo-EM) to observe biological samples at nanometer scale, close to their native state. However, poor electron penetration through biological samples sets the limit for sample thickness to less than the average size of the mammalian cell. In order to image bulky specimens at the cell or tissue level in transmission electron microscopy (TEM), a sample has to be either thinned by focused ion beam or mechanically sectioned. The latter technique, Cryo-Electron Microscopy of Vitreous Section (CEMOVIS), employs cryo-ultramicrotomy to produce sections with thicknesses of 40-100 μm of vitreous biological material suitable for cryo-EM. CEMOVIS consists of trimming and sectioning a sample with a diamond knife, placing and attaching the section onto an electron microscopy grid, transferring the grid to the cryo-electron microscope and imaging. All steps must be carried on below devitrification temperature to obtain successful results. In this chapter we provide a step-by-step guide to produce and image vitreous sections of a biological sample.

  16. TEM study of the morphology of Mn2+ -doped calcium hydroxyapatite and beta-tricalcium phosphate.

    Science.gov (United States)

    Mayer, I; Cuisinier, F J G; Gdalya, S; Popov, I

    2008-02-01

    Mn-doped carbonated hydroxyapatites (HA) were prepared by precipitation method. Ca-deficient HA samples were obtained by this method with the characteristic hexagonal apatite structure. Scanning transmission electron microscopy (STEM) of two HA samples with two different Mn content has shown that their morphology depends on their Mn content. In case of relatively low (0.73%) Mn content (HAMn1), platelet crystals about micron size and needle-like crystals up to 100 nm were observed, while with 1.23% Mn (HAMn2) crystals were smaller, needle-like and with sizes up to 400 nm only. Mn-doped TCP samples were prepared by two methods. In one case it was obtained by direct solid-state reaction with the characteristic rhombohedral structure of beta-TCP and with composition of Ca(2.7)Mn(0.3)(PO(4))(2). TEM pictures of crystals of this sample were tens of micron and submicron size with visible faces. Crystals of beta-TCP obtained by high temperature partial transformation of sample HAMn2 to beta-TCP were found by TEM to be smaller, micron sized, drop-like shaped, sensitive to beam radiation. These results indicate that the morphology of Mn doped beta-tricalcium phosphate samples depends on the method of their preparation. Morphological properties of HA and TCP are discussed and it is suggested that the smaller and less perfect HA crystals with the higher Mn-content as well as the less perfect TCP crystals obtained by transformation of HA to TCP might be of more biocompatible character.

  17. Monitoring the Stability of Perfluorocarbon Nanoemulsions by Cryo-TEM Image Analysis and Dynamic Light Scattering.

    Directory of Open Access Journals (Sweden)

    Christoph Grapentin

    Full Text Available Perfluorocarbon nanoemulsions (PFC-NE are disperse systems consisting of nanoscale liquid perfluorocarbon droplets stabilized by an emulsifier, usually phospholipids. Perfluorocarbons are chemically inert and non-toxic substances that are exhaled after in vivo administration. The manufacture of PFC-NE can be done in large scales by means of high pressure homogenization or microfluidization. Originally investigated as oxygen carriers for cases of severe blood loss, their application nowadays is more focused on using them as marker agents in 19F Magnetic Resonance Imaging (19F MRI. 19F is scarce in organisms and thus PFC-NE are a promising tool for highly specific and non-invasive imaging of inflammation via 19F MRI. Neutrophils, monocytes and macrophages phagocytize PFC-NE and subsequently migrate to inflamed tissues. This technique has proven feasibility in numerous disease models in mice, rabbits and mini pigs. The translation to clinical trials in human needs the development of a stable nanoemulsion whose droplet size is well characterized over a long storage time. Usually dynamic light scattering (DLS is applied as the standard method for determining particle sizes in the nanometer range. Our study uses a second method, analysis of transmission electron microscopy images of cryo-fixed samples (Cryo-TEM, to evaluate stability of PFC-NE in comparison to DLS. Four nanoemulsions of different composition are observed for one year. The results indicate that DLS alone cannot reveal the changes in particle size, but can even mislead to a positive estimation of stability. The combination with Cryo-TEM images gives more insight in the particulate evolution, both techniques supporting one another. The study is one further step in the development of analytical tools for the evaluation of a clinically applicable perfluorooctylbromide nanoemulsion.

  18. Correlation Analysis of TEM Images of Nanocrystal Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Micheel, Christine; Zanchet, Daniele; Alivisatos, A. Paul

    2008-05-21

    Quantitative characterizataion of images of naocrystals and nanostructures is a challenging but important task. The development and optimization of methods for the construction of complex nanostructures rely on imaging techniques. Computer programs were developed to quantify TEM images of nanocrystal/DNA nanostructures, and results are presented for heterodimers annd trimers of gold nanocrystals. The programs presented here have also been used to analyze more complex trimers and tetramers linked by branched DNA, as well as for structures made from attaching gold nanocrystals to CdSe/ZnS core-shell quantum dots. This work has the additional goal of enabling others to quickly and easily adapt the methods for their own use.

  19. TSAR modeling of a TEM horn and surrounding structure

    Science.gov (United States)

    Ng, W. C.; Pennock, S. T.

    1993-11-01

    Modeling of a TEM horn was performed with the TSAR FDTD electromagnetics code. The modeling was done in stages, beginning with the simplest case, the bare antenna itself. Complexity was added in the form of a dielectric lens, an enclosing cylinder, a layer of absorber inside the cylinder, resistive terminations between the horn and cylinder, and a flat plate over all, electrically separate from the cylinder. The final configuration included all of the above, plus a ring of ferrite inside the cylinder, just ahead of the horn. Predictions of the far-field were made at roughly ten degree increments, more closely spaced near boresight, in both vertical and horizontal planes, through the antenna's centerline. Time histories at those points were evaluated, and from the time histories power densities were calculated. Both time histories and power densities will be presented for the configurations modeled.

  20. Tem holder for sample transfer under reaction conditions

    DEFF Research Database (Denmark)

    Damsgaard, Christian Danvad; Zandbergen, Henny W.; Wagner, Jakob Birkedal

    and temperature, which usually are far from the operando conditions of e.g. heterogeneous catalysis. Our efforts focus on bridging these gaps by establishing in situ sample transfer between complementary measurement techniques. To fully exploit the capabilities of ETEM complementary experiments...... and characterization techniques are beneficial. Normally, the complementary measurements are done in parallel with experiments separated in time and space [3] or by mimicking a reactor bed by changing the feed gas composition according to reactivity and conversion measured in dedicated catalyst set-ups [4......]. Furthermore, dedicated transfer holders have been used to transfer catalyst samples between reactor set-ups and TEM at room temperature in inert atmosphere [5]. To take the full advantage of complementary in situ techniques, transfer under reactions conditions is essential. This study introduces the in situ...

  1. Oxidation of nickel particles in an environmental TEM

    DEFF Research Database (Denmark)

    Jeangros, Q.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

    challenging under these conditions. Here, nickel particles are oxidized under 3.2 mbar of O2 inside an environmental TEM (ETEM) equipped with a post-column filter [2]. Images, diffraction patterns and core-loss electron energy-loss spectra are acquired to monitor the structural and chemical evolution of Ni......The mechanisms controlling the growth of an oxide film during oxidation are subject to controversies at intermediate length scales (20-1000 nm) [1]. Relating rate-controlling mechanisms and resulting structural changes, which is essential to the understanding of oxidation processes, has proved...... nanometres in size. These domains impinge and cover the particles surface. As the temperature increases under O2, the NiO film grows and creates irregular structures composed of many crystallites. The reaction kinetics are inferred by EELS using different techniques analyzing changes in shapes of the Ni L2...

  2. Wideband TEM-TE11 mode convertor for HPM applications.

    Science.gov (United States)

    Bykov, D. N.; Bykov, N. M.; Kurkan, I. K.

    2017-05-01

    The mode convertor design of fundamental coaxial TEM to the lowest asymmetric TE11-mode of a circular waveguide was proposed and optimized with ANSYS HFSS software. It includes axially aligned parts: the input coaxial line with the high voltage insulator, conical coaxial matching line, wave-coax transition section and output circular waveguide. The most losses in this type of convertor caused by the wave of coaxial TE11-mode running back to the microwave source. To minimize these losses, there is the matching conical coaxial line with the cut-off insertion for coaxial TE11-mode. Characteristics of the convertor are as follows: the maximum input peak power - 3GW, the input impedance - 28Ohm, the central operating frequency - 1.14GHz. The power conversion efficiency to the output mode is from 90% upto 100% in the frequency band of 20%.

  3. Você tem fome de quê?

    Directory of Open Access Journals (Sweden)

    Ana Paula Gramacho Varela

    Full Text Available Este estudo objetivou pensar a obesidade à luz da teoria psicanalítica, focalizando-a como uma epidemia atual em ascendência, apesar de carregar uma antiga história. O conceito psicanalítico de pulsão, utilizado por Sigmund Freud, propiciou uma articulação teórica a partir de uma questão específica: "você tem fome de quê?", o que possibilitou um entendimento que vai além do corpo orgânico, entrando em cena o corpo pulsional. Considerando-se a abrangência em torno do conceito de pulsão, o presente estudo expressou apenas uma possibilidade de entender a obesidade, deixando em aberto questões para futuros estudos.

  4. Investigation of the agglomeration and amorphous transformation effects of neutron irradiation on the nanocrystalline silicon carbide (3C-SiC) using TEM and SEM methods

    Energy Technology Data Exchange (ETDEWEB)

    Huseynov, Elchin M., E-mail: elchin.h@yahoo.com [Department of Nanotechnology and Radiation Material Science, National Nuclear Research Center, Inshaatchilar pr. 4, AZ 1073 Baku (Azerbaijan); Institute of Radiation Problems of Azerbaijan National Academy of Sciences, B.Vahabzade 9, AZ 1143 Baku (Azerbaijan)

    2017-04-01

    Nanocrystalline 3C-SiC particles irradiated by neutron flux during 20 h in TRIGA Mark II light water pool type research reactor. Silicon carbide nanoparticles were analyzed by Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) devices before and after neutron irradiation. The agglomeration of nanoparticles was studied comparatively before and after neutron irradiation. After neutron irradiation the amorphous layer surrounding the nanoparticles was analyzed in TEM device. Neutron irradiation defects in the 3C-SiC nanoparticles and other effects investigated by TEM device. The effect of irradiation on the crystal structure of the nanomaterial was studied by selected area electron diffraction (SAED) and electron diffraction patterns (EDP) analysis.

  5. Hollow nitrogen-containing core/shell fibrous carbon nanomaterials as support to platinum nanocatalysts and their TEM tomography study

    Science.gov (United States)

    Zhou, Cuifeng; Liu, Zongwen; Du, Xusheng; Mitchell, David Richard Graham; Mai, Yiu-Wing; Yan, Yushan; Ringer, Simon

    2012-03-01

    Core/shell nanostructured carbon materials with carbon nanofiber (CNF) as the core and a nitrogen (N)-doped graphitic layer as the shell were synthesized by pyrolysis of CNF/polyaniline (CNF/PANI) composites prepared by in situ polymerization of aniline on CNFs. High-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared and Raman analyses indicated that the PANI shell was carbonized at 900°C. Platinum (Pt) nanoparticles were reduced by formic acid with catalyst supports. Compared to the untreated CNF/PANI composites, the carbonized composites were proven to be better supporting materials for the Pt nanocatalysts and showed superior performance as catalyst supports for methanol electrochemical oxidation. The current density of methanol oxidation on the catalyst with the core/shell nanostructured carbon materials is approximately seven times of that on the catalyst with CNF/PANI support. TEM tomography revealed that some Pt nanoparticles were embedded in the PANI shells of the CNF/PANI composites, which might decrease the electrocatalyst activity. TEM-energy dispersive spectroscopy mapping confirmed that the Pt nanoparticles in the inner tube of N-doped hollow CNFs could be accessed by the Nafion ionomer electrolyte, contributing to the catalytic oxidation of methanol.

  6. Confocal Raman microscopy

    CERN Document Server

    Dieing, Thomas; Hollricher, Olaf

    2018-01-01

    This second edition provides a cutting-edge overview of physical, technical and scientific aspects related to the widely used analytical method of confocal Raman microscopy. The book includes expanded background information and adds insights into how confocal Raman microscopy, especially 3D Raman imaging, can be integrated with other methods to produce a variety of correlative microscopy combinations. The benefits are then demonstrated and supported by numerous examples from the fields of materials science, 2D materials, the life sciences, pharmaceutical research and development, as well as the geosciences.

  7. Characterization by SEM, TEM and Quantum-Chemical Simulations of the Spherical Carbon with Nitrogen (SCN Active Carbon Produced by Thermal Decomposition of Poly(vinylpyridine-divinylbenzene Copolymer

    Directory of Open Access Journals (Sweden)

    Vladyslav V. Lisnyak

    2009-09-01

    Full Text Available Amorphous Spherical Carbon with Nitrogen (SCN active carbon has been prepared by carbonization of poly(vinylpyridine-divinylbenzene (PVPDVB copolymer. The PVPDVB dehydrogenation copolymer has been quantum chemically (QC simulated using cluster and periodic models. Scanning electron microscopy (SEM, transmission electron microscopy (TEM and energy dispersive X-ray (EDX studies of the resulting product have conformed the QC computation results. Great structural similarity is found both at the nano- and micro-levels between the N-doped SCN carbon and its pure carbonic SKS analog.

  8. Determination of Morphological Parameters of Supported Gold Nanoparticles: Comparison of AFM Combined with Optical Spectroscopy and Theoretical Modeling versus TEM

    Directory of Open Access Journals (Sweden)

    Frank Hubenthal

    2012-07-01

    Full Text Available The morphology of small gold particles prepared by Volmer–Weber growth on sapphire substrates have been investigated by two different characterization techniques. First, by non-extensive atomic force microscopy (AFM in combination with optical spectroscopy and modeling of the optical properties using a theoretical model, recently developed in our group. Second, by extensive transmission electron microscopy (TEM. Comparing the results obtained with both techniques demonstrate that for small gold nanoparticles within the quasistatic limit, the morphological properties can be precisely determined by an appropriate theoretical modeling of the optical properties in combination with simple AFM measurements. The apparent mean axial ratio of the nanoparticles, i.e., the axial ratio that corresponds to the center frequency of the ensemble plasmon resonance, is obtained easily from the extinction spectrum. The mean size is determined by the nanoparticle number density and the amount of deposited material, measured by AFM and a quartz micro balance, respectively. To extract the most probable axial ratio of the nanoparticle ensemble, i.e., the axial ratio that corresponds to the most probable nanoparticle size in the ensemble, we apply the new theoretical model, which allows to extract the functional dependence of the nanoparticle shape on its size. The morphological parameters obtained with this procedure will be afterwards compared to extensive TEM measurements. The results obtained with both techniques yield excellent agreement. For example, the lateral dimensions of the nanoparticles after deposition of 15.2 × 1015 atoms/cm2 of gold has been compared. While a mean lateral diameter of (13 ± 2 nm has been extracted from AFM, optical spectroscopy and modeling, a value of (12 ± 2 nm is derived from TEM. The consistency of the results demonstrate the precision of our new model. Moreover, since our theoretical model allows to extract the functional

  9. Early studies of placental ultrastructure by electron microscopy

    DEFF Research Database (Denmark)

    Carter, A M; Enders, A C

    2016-01-01

    BACKGROUND: Transmission electron microscopy (TEM) was first applied to study placental ultrastructure in the 1950's. We review those early studies and mention the scientists that employed or encouraged the use of TEM. FINDINGS: Among the pioneers Edward W. Dempsey was a key figure who attracted...... many other scientists to Washington University in St. Louis. Work on human placental ultrastructure was initiated at Cambridge and Kyoto whilst domestic animals were initially studied by Björkman in Stockholm and electron micrographs of bat placenta were published by Wimsatt of Cornell University....... CONCLUSIONS: Prior to the introduction of better fixation techniques, TEM images were of modest technical quality. Nevertheless they gave important insights into placental ultrastructure, particularly the nature of the maternal-fetal interface....

  10. TEM investigation of the surface layer structure [111]{sub B2} of the single NiTi crystal modified by the Si-ion beam implantation

    Energy Technology Data Exchange (ETDEWEB)

    Girsova, S. L., E-mail: girs@ispms.tsc.ru; Poletika, T. M., E-mail: poletm@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Meisner, S. N., E-mail: msn@ispms.tsc.ru; Meisner, L. L., E-mail: llm@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The study was carried on for the single NiTi crystals subjected to the Si-ion beam implantation. Using the transmission electron microscopy technique (TEM), the surface layer structure [111]{sub B2} was examined for the treated material. The modified near-surface sublayers were found to have different composition. Thus the uppermost sublayer contained mostly oxides; the lower-lying modified sublayer material was in an amorphous state and the thin underlying sublayer had a defect structure.

  11. International Multidisciplinary Microscopy Congress

    CERN Document Server

    Oral, Ahmet; Ozer, Mehmet; InterM; INTERM2013

    2014-01-01

    The International Multidisciplinary Microscopy Congress (INTERM2013) was organized on October 10-13, 2013. The aim of the congress was to bring together scientists from various branches to discuss the latest advances in the field of microscopy. The contents of the congress have been broadened to a more "interdisciplinary" scope, so as to allow all scientists working on related subjects to participate and present their work. These proceedings include 39 peer-reviewed technical papers, submitted by leading academic and research institutions from over 12 countries and representing some of the most cutting-edge research available. The 39 papers are grouped into the following sections: - Applications of Microscopy in the Physical Sciences - Applications of Microscopy in the Biological Sciences

  12. Clinical specular microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hirst, L.W.; Laing, R.A.

    1987-01-01

    This book provides the general ophthalmologist with a guide to the clinical applications of specular microscopy. Important material is included on laser injury, cataract surgery, corneal transplants, glaucoma, uveitis, and trauma.

  13. Structural characterizaiton and gas reactions of small metal particles by high-resolution, in-situ TEM and TED

    Science.gov (United States)

    1984-01-01

    The existing in-situ transmission electron microscopy (TEM) facility was improved by adding a separately pumped mini-specimen chamber. The chamber contains wire-evaporation sources for three metals and a specimen heater for moderate substrate temperatures. A sample introduction device was constructed, installed, and tested, facilitating rapid introduction of a specimen into the mini-chamber while maintaining the background pressure in that chamber in the 10(-9) millibar range. Small particles and clusters of Pd, grown by deposition from the vapor phase in an in-situ TEM facility on amorphous and crystalline support films of alumina and on ultra-thin carbon films, were analyzed by conventional high-resolution TEM and image analysis in terms of detectability, number density, and size distribution. The smallest particles that could be detected and counted contained no more than 6 atoms; size determinations could be made for particles 1 nm in diameter. The influence of various oxygen plasma treatments, annealing treatments, and of increasing the substrate temperature during deposition was investigated. The TEM technique was employed to demonstrate that under otherwise identica l conditions the lattice parameter of Pd particles in the 1 to 2 nm size range and supported in random orientation on ex-situ prepared mica films is expanded by some 3% when compared to 5 nm size particles. It is believed that this expansion is neither a small-particle diffraction effect nor due to pseudomorphism, but that it is due to a annealing-induced transformation of the small as-deposited particles with predominantly composite crystal structures into larger particles with true f.c.c. structure and thus inherently smaller lattice parameter.

  14. Quantitative dispersion microscopy

    OpenAIRE

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

    2010-01-01

    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...

  15. Imaging and Quantification of Extracellular Vesicles by Transmission Electron Microscopy.

    Science.gov (United States)

    Linares, Romain; Tan, Sisareuth; Gounou, Céline; Brisson, Alain R

    2017-01-01

    Extracellular vesicles (EVs) are cell-derived vesicles that are present in blood and other body fluids. EVs raise major interest for their diverse physiopathological roles and their potential biomedical applications. However, the characterization and quantification of EVs constitute major challenges, mainly due to their small size and the lack of methods adapted for their study. Electron microscopy has made significant contributions to the EV field since their initial discovery. Here, we describe the use of two transmission electron microscopy (TEM) techniques for imaging and quantifying EVs. Cryo-TEM combined with receptor-specific gold labeling is applied to reveal the morphology, size, and phenotype of EVs, while their enumeration is achieved after high-speed sedimentation on EM grids.

  16. Structure of the extended-spectrum β-lactamase TEM-72 inhibited by citrate

    OpenAIRE

    Docquier, Jean-Denis; Benvenuti, Manuela; Calderone, Vito; Rossolini, Gian-Maria; Mangani, Stefano

    2011-01-01

    TEM-72 is a quadruple mutant of TEM-1 and shows extended-spectrum β-lactamase properties. The present structure shows the presence of a citrate anion bound to the TEM-72 active site and supports the use of polycarboxylates as a scaffold for the design of broad-spectrum inhibitors of serine β-lactamases.

  17. Molecular identification of TEM-116 beta-lactamase gene in isolates ...

    African Journals Online (AJOL)

    Methods: Sequence analysis of TEM beta-lactamase isolates and their antibiotic susceptibility patterns ... One TEM-116 P. aeruginosa (PA11) isolate was resistant to all available antibiotics. Conclusion: These results reveal increased antibiotic resistance in the TEM-116 ..... pertaining to claims relating to the content of this.

  18. Quantitative In Situ TEM Studies of Small-Scale Plasticity in Irradiated and Unirradiated Metals

    Science.gov (United States)

    Chisholm, Claire

    In this work, unirradiated and irradiated model body centered cubic (BCC) and face centered cubic (FCC) materials are investigated using advanced electron microscopy techniques to quantitatively measure local stresses and strains around defects, with the overarching goal of obtaining a fundamental understanding of defect physics. Quantitative in-situ transmission electron microscopy (TEM) tensile tests are performed with Molybdenum-alloy nano-fibers, functioning as a model BCC structural material. Local true stress and strain around an active Frank-Read type dislocation source are obtained using quantitative load-displacement data and digital image correlation. A mixed Frank-Read dislocation source, b=a/2[-1-11](112) with a line direction 20° from a screw orientation and length 177 nm, is observed to begin operating at a measured local stress of 1.38 GPa. The measured local true stress values compare very well to estimated stresses using dislocation radius of curvature, and a line-tension model of a large bow-out configuration, with differences of only ˜1%. The degree to which the local true stresses can be measured is highly promising. However, the ultimate failure mode of these fibers, sudden strain softening after dislocation starvation and exhaustion, cannot be captured at the typical camera frame rate of 30 frames per second. Thus, fibers are mechanically tested while under observation with the Gatan K2-IS direct electron detector camera, where the frame rate is an order of magnitude larger at 400 fps. Though the increase in frame rate adds to the overall understanding of the sudden failure, by definitively showing that the nano-fibers break rather than strain soften, the failure mechanism still operates too quickly to be observed. In the final investigation of this BCC model structural alloy, the mechanical behavior of heavily dislocated, but unirradiated, and He1+ and Ni 2+ irradiated nano-fibers are compared. Remarkable similarities are found in the

  19. Multi-modal Registration for Correlative Microscopy using Image Analogies

    Science.gov (United States)

    Cao, Tian; Zach, Christopher; Modla, Shannon; Powell, Debbie; Czymmek, Kirk; Niethammer, Marc

    2014-01-01

    Correlative microscopy is a methodology combining the functionality of light microscopy with the high resolution of electron microscopy and other microscopy technologies for the same biological specimen. In this paper, we propose an image registration method for correlative microscopy, which is challenging due to the distinct appearance of biological structures when imaged with different modalities. Our method is based on image analogies and allows to transform images of a given modality into the appearance-space of another modality. Hence, the registration between two different types of microscopy images can be transformed to a mono-modality image registration. We use a sparse representation model to obtain image analogies. The method makes use of corresponding image training patches of two different imaging modalities to learn a dictionary capturing appearance relations. We test our approach on backscattered electron (BSE) scanning electron microscopy (SEM)/confocal and transmission electron microscopy (TEM)/confocal images. We perform rigid, affine, and deformable registration via B-splines and show improvements over direct registration using both mutual information and sum of squared differences similarity measures to account for differences in image appearance. PMID:24387943

  20. Multi-modal registration for correlative microscopy using image analogies.

    Science.gov (United States)

    Cao, Tian; Zach, Christopher; Modla, Shannon; Powell, Debbie; Czymmek, Kirk; Niethammer, Marc

    2014-08-01

    Correlative microscopy is a methodology combining the functionality of light microscopy with the high resolution of electron microscopy and other microscopy technologies for the same biological specimen. In this paper, we propose an image registration method for correlative microscopy, which is challenging due to the distinct appearance of biological structures when imaged with different modalities. Our method is based on image analogies and allows to transform images of a given modality into the appearance-space of another modality. Hence, the registration between two different types of microscopy images can be transformed to a mono-modality image registration. We use a sparse representation model to obtain image analogies. The method makes use of corresponding image training patches of two different imaging modalities to learn a dictionary capturing appearance relations. We test our approach on backscattered electron (BSE) scanning electron microscopy (SEM)/confocal and transmission electron microscopy (TEM)/confocal images. We perform rigid, affine, and deformable registration via B-splines and show improvements over direct registration using both mutual information and sum of squared differences similarity measures to account for differences in image appearance. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. On strain state and pseudo-moire TEM contrast of InSb quantum dots coherently grown on InAs surface

    Energy Technology Data Exchange (ETDEWEB)

    Bert, N.A. [Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021 St. Petersburg (Russian Federation); Freidin, A.B.; Kolesnikova, A.L.; Korolev, I.K. [Institute of Problems in Mechanical Engineering, Bolshoj 61, Vas. Ostrov, 199178 St. Petersburg (Russian Federation); Romanov, A.E. [Ioffe Physico-Technical Institute, Polytechnicheskaya 26, 194021 St. Petersburg (Russian Federation); Polytechnique School, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

    2010-10-15

    In this article, we report on the theoretical analysis of transmission electron microscopy (TEM) images of surface InSb quantum dots (QDs) coherently grown on InAs substrate. A finite element method (FEM) is used to calculate elastic fields and total displacements in a QD and an adjusted region of the substrate. The effects of QD form factor and QD aspect ratio {delta} on displacements and TEM images are analyzed. A quasilinear dependence of radial displacements on radial coordinate for spherical, elliptical, and truncated spherical QDs is demonstrated. It has been found that the displacement field does not depend on the shape and aspect ratio for QDs with {delta}>{delta}{sub c1}, and the upper part of a QD remains practically undistorted for QDs with {delta}{>=}{delta}{sub c2}. For InSb/InAs heterosystem these critical values are {delta}{sub c1}{approx} 0.13 and {delta}{sub c2}{approx} 0.33. The total displacements are used for computation of TEM diffraction contrast associated with QDs. To achieve this the Howie-Whelan dynamic approach is utilized. Calculated TEM images of heavily strained QDs demonstrate the picture of pseudo-moire with a strong dependence of moire-like fringe distance {delta} on aspect ratio {delta}. This dependence gives the possibility to determine the aspect ratio and height of QDs from the results of TEM experiments. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  2. JORNALISMO QUE TEM LADO: O CASO DOS BLOGUEIROS BRASILEIROS "PROGRESSISTAS"

    Directory of Open Access Journals (Sweden)

    Liziane Soares Guazina

    2013-12-01

    Full Text Available Neste artigo, analisamos como se constitui a identidade profissional de um grupo de jornalistas experientes e atuantes no mercado, que, ao mesmo tempo, assinam blogs independentes para expressar sua opinião política e se assumem publicamente como  "progressistas" ou "sujos". Nosso objetivo é compreender como esses blogueiros definem e praticam o jornalismo em seus blogs, e como entendem sua própria atuação no contexto democrático. A partir de entrevistas, mapeamos os principais valores jornalísticos expressos por eles, delineando sua identidade profissional de jornalistas-blogueiros que defendem um jornalismo "que tem lado", isto é, de opinião. Os resultados mostram que esses jornalistas consideram seus blogs lugar de diversidade de opinião em oposição à mídia tradicional, e que sua principal função, enquanto jornalistas, é atuar de maneira vigilante em relação aos todos poderes políticos, incluindo a mídia, vista como ator político relevante.

  3. Aquifer characterisation in East Timor, with ground TEM

    Science.gov (United States)

    Ley-Cooper, A.

    2011-12-01

    An assessment of Climate Change Impacts on Groundwater Resources in East Timor led by Geosciences Australia is aimed at assisting East Timor's government to better understand and manage their groundwater resources. Form the current known information most aquifers in Timor-Leste are recharged by rainfall during the wet season. There is a concern that without a regular recharge, the stored groundwater capacity will decrease. Timor's population increase has caused a higher demand for groundwater which is currently been met by regulated pumping bores which are taped into deep aquifers, plus the sprouting of unregulated spear point bores in the shallow aquifers . Both groundwater recharge and the aquifers morphology need to be better understood in order to ensure supply and so groundwater can be managed for the future. Current weather patterns are expected to change and this could cause longer periods of drought or more intense rainfall, which in turn, would affect the availability and quality of groundwater. Salt water intrusions pose a threat on the low-lying aquifers as sea level rises. Australia's CSIRO has undertaken a series hydrogeophysical investigations employing ground TEM to assist in the characterisation of three aquifers near Dili, Timor Leste's capital. Interpreting ground water chemistry and dating; jointly with EM data has enhanced the understanding of the aquifers architecture, groundwater quality and helped identify potential risks of seawater intrusions.

  4. TEM study of impurity segregations in beryllium pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Klimenkov, M., E-mail: michael.klimenkov@kit.edu [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chakin, V.; Moeslang, A. [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rolli, R. [Institute for Applied Materials – Materials and Biomechanics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-15

    Beryllium is planned to be used as a neutron multiplier in the Helium-cooled Pebble Bed European concept of a breeding blanket of demonstration power reactor DEMO. In order to evaluate the irradiation performance, individual pebbles and constrained pebble beds were neutron-irradiated at temperatures typical of fusion blankets. Beryllium pebbles 1 mm in diameter produced by the rotating electrode method were subjected to a TEM study before and after irradiation at High Flux Reactor, Petten, Netherlands at 861 K. The grain size varied in a wide range from sub-micron size up to several tens of micrometers, which indicated formation bimodal grain size distribution. Based on the application of combined electron energy loss spectroscopy and energy dispersive X-ray spectroscopy methods, we suggest that impurity precipitates play an important role in controlling the mechanical properties of beryllium. The impurity elements were present in beryllium at a sub-percent concentration form beryllide particles of a complex (Fe/Al/Mn/Cr)B composition. These particles are often ordered along dislocations lines, forming several micron-long chains. It can be suggested that fracture surfaces often extended along these chains in irradiated material.

  5. Correlated NanoSIMS, TEM, and XANES Studies of Presolar Grains

    Science.gov (United States)

    Groopman, Evan Edward

    The objective of this thesis is to describe the correlated study of individual presolar grains via Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS), Transmission Electron Microscopy (TEM), and Scanning Transmission X-ray Microscopy (STXM) utilizing X-ray Absorption Near Edge Structure (XANES), with a focus on connecting these correlated laboratory studies to astrophysical phenomena. The correlated isotopic, chemical, and microstructural studies of individual presolar grains provide the most detailed description of their formation environments, and help to inform astrophysical models and observations of stellar objects. As a part of this thesis I have developed and improved upon laboratory techniques for micromanipulating presolar grains and embedding them in resin for ultramicrotomy after NanoSIMS analyses and prior to TEM characterization. The new methods have yielded a 100% success rate and allow for the specific correlation of microstructural and isotopic properties of individual grains. Knowing these properties allows for inferences to be made regarding the condensation sequences and the origins of the stellar material that condensed to form these grains. NanoSIMS studies of ultramicrotomed sections of presolar graphite grains have revealed complex isotopic heterogeneities that appear to be primary products of the grains' formation environments and not secondary processing during the grains' lifetimes. Correlated excesses in 15N and 18O were identified as being carried by TiC subgrains within presolar graphite grains from supernovae (SNe). These spatially-correlated isotopic anomalies pinpoint the origin of the material that formed these grains: the inner He/C zone. Complex microstructures and isotopic heterogeneities also provide evidence for mixing in globular SN ejecta, which is corroborated by models and telescopic observations. In addition to these significant isotopic discoveries, I have also observed the first reported nanocrystalline core

  6. In situ TEM Raman spectroscopy and laser-based materials modification

    Energy Technology Data Exchange (ETDEWEB)

    Allen, F.I., E-mail: fiallen@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kim, E. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Andresen, N.C. [Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Grigoropoulos, C.P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Minor, A.M., E-mail: aminor@lbl.gov [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2017-07-15

    We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS{sub 2} combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS{sub 2} are performed in situ.

  7. TEM, FISH and molecular studies in infertile men with pericentric inversion of chromosome 9.

    Science.gov (United States)

    Collodel, G; Moretti, E; Capitani, S; Piomboni, P; Anichini, C; Estenoz, M; Baccetti, B

    2006-08-01

    Pericentric inversions involving the secondary constriction (qh) region of chromosome 9 are considered to be normal variants of human karyotype. A number of investigators have suggested that chromosomal anomalies can contribute to human infertility causing spermatogenetic derangement. The present study was aimed at verifying the influence of chromosome 9 inversion on human spermatogenesis. Semen samples of 18 male carriers of chromosome 9 inversion, analysed by light microscopy, revealed that five patients were azoospermic. PCR analysis demonstrated that two of them also had Y microdeletions. The other 13 showed generally normal sperm concentrations and reduced motility. The morphological characteristics of sperm were studied by TEM and the data were elaborated by a mathematical formula. Sperm pathologies resulted more frequently in the studied group compared to controls, particularly apoptosis. Partial sequences of the A-kinase anchoring protein (Akap) 4 and 3 genes were performed in all patients, as a previous study by our group highlighted Dysplasia of Fibrous Sheath (DFS) defect in two men with inv 9 investigations. The possible effect of chromosome 9 inversion on meiotic chromosome segregation was investigated by FISH, which showed an increased incidence of diploidy. We hypothesized that this inversion could have variable effects on spermatogenesis, from azoospermia to severely altered sperm morphology, motility and meiotic segregation.

  8. TEM Nanostructural Study of Al-6Si-3Cu-Mg Melt-Spun Ribbons

    Directory of Open Access Journals (Sweden)

    Ismeli Alfonso López

    2008-01-01

    Full Text Available Three quaternary Al-6Si-3Cu-xMg (x = 0.59, 3.80, and 6.78 wt.% alloys were produced by melt-spun and characterized using X-ray diffractometry (XRD, transmission electron microscopy (TEM, and microhardness techniques. Obtained second phases were Al2Cu( for the alloy with 0.59% Mg and Al5Cu2Mg8Si6 (Q for the alloys with 3.80 and 6.78% Mg. These phases are present as 30–50 nm or as 5–10 nm nanoparticles. Alloying elements content in solid solution increased, mainly for Si and Mg. The high alloying elements content in solid solution and the small -Al cell size for melt-spun alloys leads to microhardness values about 2 times higher than those of ingot counterparts. The microhardness increase for melt-spun alloys with 3.80 and 6.78% Mg depends on Mg content in solid solution.

  9. Analysis of polycrystalline SrRuO3 by TEM and EELS

    Science.gov (United States)

    Ito, Yasuo; Klamut, Piotr; Dabrowski, Bogdan; Maxwell, Mike

    2002-03-01

    Analysis of polycrystalline SrRuO3 by TEM and EELS Y. Ito, P. W. Klamut , B. Dabrowski, M. Maxwell Department of Physics, Northern Illinois University, DeKalb, IL Two polycrystalline SrRuO3 samples were prepared (1) in the conventional manner (Curie temperature TC = 165K) and (2) at high pressure of oxygen resulting in substantially lower TC (= 90K). The Mössbauer Ru (99) analysis of the sample (1) showed a unique hyperfine magnetic field and, corresponding to one Ru site (+4) and a broad single line above the TC (96K), indicating the presence of multiple sites and/or electric quadrupole interaction for the sample (2) [1]. Here, we investigate the microscopic origins of the above differences and the relationship between microstructure, composition, and electronic structure of these two polycrystalline SrRuO3 by using transmission electron microscopy and electron energy-loss spectroscopy (EELS). [1] M. DeMarco, P.W. Klamut, B. Dabrowski, S. Toorongian and M. Haka, see abstract of this meeting. Supported by NSF-DMR-0105398, and HECA.

  10. TEM characterization of in-reactor neutron irradiated CANDU spacer material Inconel X-750

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, He Ken [Department of Mechanical and Materials Engineering, Queen’s University Kingston, Ontario K7L 3N6 (Canada); Yao, Zhongwen, E-mail: yaoz@me.queensu.ca [Department of Mechanical and Materials Engineering, Queen’s University Kingston, Ontario K7L 3N6 (Canada); Morin, Gregory; Griffiths, Malcolm [Deformation Technology Branch, AECL – Chalk River Laboratories Chalk River, Ontario K0J 1J0 (Canada)

    2014-08-01

    The irradiation induced defects in CANDU Inconel X-750 spacers, which were removed from reactors after about 14 effective full power years, were examined by transmission electron microscopy (TEM). The spacers in the form of garter springs were reported to operate at various temperatures depending on locations. Two samples from different locations with different estimated irradiation temperatures were tested: (1) ∼180 °C at 6 o’clock position and (2) ⩾300 °C at 12 o’clock position. Obvious temperature effects were observed. In the ∼180 °C irradiated sample, a high density of small lattice defects (1–3 nm) developed during irradiation, including stacking fault tetrahedra and both 1/3 〈1 1 1〉 and ½ 〈1 1 0〉 type dislocation loops. A uniform distribution of small cavities (∼1–3 nm) was observed. In >300 °C irradiated sample, apart from small point defect clusters, large Frank type interstitial loops presented. The sizes of the cavities were also greater than those in the ∼180 °C irradiated sample. The distribution of cavities was more heterogeneous and an obvious agglomeration of cavities to grain boundaries and phase boundaries were observed. In both samples, dissolution of the primary strengthening phase γ′ was noted.

  11. EPR, TEM and cell viability study of asbestiform zeolite fibers in cell media.

    Science.gov (United States)

    Cangiotti, Michela; Salucci, Sara; Battistelli, Michela; Falcieri, Elisabetta; Mattioli, Michele; Giordani, Matteo; Ottaviani, Maria Francesca

    2018-01-01

    Human monocyte U937 cell line was used as a model to verify the toxicity of erionite and offretite asbestiform zeolite fibers. As a presumed non-toxic reference, a fibrous scolecite zeolite was also used. To analyze the process of fiber ingestion into cells and the cells-fibers interactions, a spin-probe electron paramagnetic resonance (EPR) analysis was performed supported by transmission electron microscopy (TEM) and cell viability measurements as a function of the incubation time. Erionite fibers were fast internalized in the membrane mainly as aggregates with radical-solution drops trapped inside, and were found in the cytosol and at the nucleus. In 24h, first erionite fibers rich in sodium and potassium, and then calcium-rich erionite fibers, induced cell necrosis. The offretite fibers formed rounding electron-dense filaments which transformed in curved filaments, initially perturbing the cell structure and interacting at the external surface more than erionite fibers. Such interactions probably diminished the toxic effect of offretite on cells. Interestingly, the presumed non-toxic scolecite fibers were partially internalized, inducing formation of swollen mitochondria and squared cells. Overall, the toxic effect of the fibrous zeolites was related to fiber morphology, chemical distribution of sites, structural variations and formation of aggregates. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Advanced 2D and 3D Electron Microscopy Analysis of Clay/PP Nanocomposites

    DEFF Research Database (Denmark)

    Mosca, Alessandra; Roberts, Ashley; Daviðsdóttir, Svava

    2011-01-01

    consisting of 3 wt% modified clay in a PP matrix was studied. Prior to microscopy analyses, SEM or TEM samples were cryo-microtomed to a flat surface or thin sections (70 nm), respectively. An FEI Titan T20 TEM microscope operating at 200 kV was used for 2D imaging. An FEI Helios focussed ion beam (FIB...... SEM micrograph obtained with the TLD detector. High magnification and resolution comparable with that of TEM (see Figure 3 (b)) are achieved. Conclusions To the best of our knowledge, this is the first work showing the great advantages of FIB/FEG SEM imaging with TLD (namely larger field of view...

  13. Transmission electron microscopy of unstained hybrid Au nanoparticles capped with PPAA (plasma-poly-allylamine)

    DEFF Research Database (Denmark)

    Gontard, Lionel C.; Fernández, Asunción; Dunin-Borkowski, Rafal E.

    2014-01-01

    of the organic molecular components remains largely unknown. Here, we apply TEM to the physico-chemical characterization of Au nanoparticles that are coated with plasma-polymerized-allylamine, an organic compound with the formula C3H5NH2. We discuss the use of energy-filtered TEM in the low-energy-loss range......Hybrid (organic shell-inorganic core) nanoparticles have important applications in nanomedicine. Although the inorganic components of hybrid nanoparticles can be characterized readily using conventional transmission electron microscopy (TEM) techniques, the structural and chemical arrangement...

  14. (TEM) observations of shock damage in the Tenham chondrite

    Science.gov (United States)

    Langenhorst, F.; Joreau, P.; Doukhan, J. C.

    1994-07-01

    Among the ordinary chondrites, the Tenham meteorite (L6) is an instructive example of strong shock metamorphism. It is randomly pervaded by pseudotachylite-like shock veins that contain ringwoodite and majorite, the high-pressure phases of olivine and pyroxene, respectively. According to the revised shock nomenclature of ordinary chondrites, this shock signature is characteristic for shock stage S6 with pressures in excess of 50-55 GPa. In contrast to previous transmission electron microscope (TEM) studies, concentrating on the formation of the high-pressure phases in shock veins, our goal was to characterize the shock defects in olivine, pyroxene, and plagioclase occurring in the bulk of Tenham, i.e., outside shock veins. In olivine, shock has caused the formation of irregular and planar fractures as well as the activation of numerous dislocations. Planar fractures can be either filled with alteration products of Fe-Ni alloy. By far, diopside displays the greatest diversity of shock-induced defects; these are mechanical twins, numerous dislocations, and planar deformation features (PDFs). Diffuse scattering rings in electron diffraction patterns reveal that they consist of amorphous material. In analogy to quartz, it is reasonable to call them PDFs, too. The predominant shock effect in plagioclase is the formation of PDFs. Up to three crossing sets of such parallel, amorphous lamellae have been observed. It is concluded that almost all lattice defects observed in the silicate phases of Tenham are compatible with an impact origin. Some of the defects have been calibrated by shock experiments and, hence, give clues to the shock pressure.

  15. Confocal Raman Microscopy

    CERN Document Server

    Dieing, Thomas; Toporski, Jan

    2011-01-01

    Confocal Raman Microscopy is a relatively new technique that allows chemical imaging without specific sample preparation. By integrating a sensitive Raman spectrometer within a state-of-the-art microscope, Raman microscopy with a spatial resolution down to 200nm laterally and 500nm vertically can be achieved using visible light excitation. Recent developments in detector and computer technology as well as optimized instrument design have reduced integration times of Raman spectra by orders of magnitude, so that complete images consisting of tens of thousands of Raman spectra can be acquired in seconds or minutes rather than hours, which used to be standard just one decade ago. The purpose of this book is to provide the reader a comprehensive overview of the rapidly developing field of Confocal Raman Microscopy and its applications.

  16. Confocal scanning microscopy

    DEFF Research Database (Denmark)

    Bariani, Paolo

    This report is based on a metrological investigation on confocal microscopy technique carried out by Uffe Rolf Arlø Theilade and Paolo Bariani. The purpose of the experimental activity was twofold a metrological instrument characterization and application to assessment of rough PP injection moulded...... replicated topography. Confocal microscopy is seen to be a promising technique in metrology of microstructures. Some limitations with respect to surface metrology were found during the experiments. The experiments were carried out using a Zeiss LSM 5 Pascal microscope owned by the Danish Polymer Centre...

  17. Gonococcal Antimicrobial Susceptibility and the Prevalence of blaTEM-1 and blaTEM-135 Genes in Neisseria gonorrhoeae Isolates from Thailand.

    Science.gov (United States)

    Tribuddharat, Chanwit; Pongpech, Pintip; Charoenwatanachokchai, Angkana; Lokpichart, Somchai; Srifuengfung, Somporn; Sonprasert, Suthatta

    2017-03-24

    We studied the antimicrobial susceptibility and prevalence of the blaTEM-1 and blaTEM-135 genes in Neisseria gonorrhoeae isolates obtained in Thailand. The isolates were tested using the disk diffusion method, and 100% of 370 isolates were found susceptible to cefixime, ceftriaxone, cefotaxime, ceftazidime, cefepime, spectinomycin, and azithromycin. Some of the isolates were resistant to penicillin (85.7%), ciprofloxacin (88.0%), ofloxacin (97.4%), or tetracycline (89.1%). Penicillinase-producing N. gonorrhoeae accounted for 83.8% of isolates, with 70.0% of these further identified as penicillinase-producing plus tetracycline resistant N. gonorrhoeae. Penicillin, tetracycline, and ciprofloxacin are not recommended for treatment because of the high prevalence (89.7%) of multidrug resistant gonococci. A study of genes controlling enzyme of beta-lactamase production (blaTEM-1 and blaTEM-135) was performed using mismatch amplification mutation assay PCR method and DNA sequencing. Beta-lactamase positive N. gonorrhoeae carried blaTEM-1 (69.6%) and blaTEM-135 (30.4%), indicating that there is a significant increase and spread of blaTEM-135 among gonococci in Thailand.

  18. Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

    Science.gov (United States)

    Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

    2013-11-26

    The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (μ) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ∼2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of μ on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ∼3.5 nm thick layer (mean dissociation pK ∼ 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ∼ 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film.

  19. Scanning ultrafast electron microscopy.

    Science.gov (United States)

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

    2010-08-24

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

  20. Single particle electron microscopy

    NARCIS (Netherlands)

    Boekema, Egbert J.; Folea, Mihaela; Kouril, Roman

    2009-01-01

    Electron microscopy (EM) in combination with image analysis is a powerful technique to study protein structures at low, medium, and high resolution. Since electron micrographs of biological objects are very noisy, improvement of the signal-to-noise ratio by image processing is an integral part of

  1. and transmission electron microscopy

    African Journals Online (AJOL)

    Administrator

    immune-electron microscopy (IEM) from patients' feces. They reported this virus particle as the causative agent of winter vomiting outbreaks in Norwalk (Kapikian et al.,. 1972). This is the remarkable landmark study of non- bacterial gastroenteritis viruses, especially for small round structured viruses (SRSVs). After that, many.

  2. Atomic Force Microscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Atomic Force Microscopy - A Tool to Unveil the Mystery of Biological Systems ... Transcription and Disease Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560 ...

  3. Photoacoustic computed microscopy

    Science.gov (United States)

    Yao, Lei; Xi, Lei; Jiang, Huabei

    2014-05-01

    Photoacoustic microscopy (PAM) is emerging as a powerful technique for imaging microvasculature at depths beyond the ~1 mm depth limit associated with confocal microscopy, two-photon microscopy and optical coherence tomography. PAM, however, is currently qualitative in nature and cannot quantitatively measure important functional parameters including oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), oxygen saturation (sO2), blood flow (BF) and rate of oxygen metabolism (MRO2). Here we describe a new photoacoustic microscopic method, termed photoacoustic computed microscopy (PACM) that combines current PAM technique with a model-based inverse reconstruction algorithm. We evaluate the PACM approach using tissue-mimicking phantoms and demonstrate its in vivo imaging ability of quantifying HbO2, HbR, sO2, cerebral BF and cerebral MRO2 at the small vessel level in a rodent model. This new technique provides a unique tool for neuroscience research and for visualizing microvasculature dynamics involved in tumor angiogenesis and in inflammatory joint diseases.

  4. Second harmonic generation microscopy

    DEFF Research Database (Denmark)

    Brüggemann, Dagmar Adeline; Brewer, Jonathan R.; Risbo, Jens

    2010-01-01

    -temperature endotherm peak observable in the differential scanning calorimetry (DSC) thermograms. DSC analysis of epimysium, the connective tissue layer that enfold skeletal muscles, produces one large endotherm starting at 57 °C and peaking at 59.5 °C. SHG microscopy of collagen fibers reveals a variability of thermal...

  5. Magnetic Force Microscopy

    NARCIS (Netherlands)

    Abelmann, Leon

    Principle of MFM In magnetic force microscopy (MFM), the magnetic stray field above a very flat specimen, or sample, is detected by placing a small magnetic element, the tip, mounted on a cantilever spring very close to the surface of the sample (Figure 1). Typical dimensions are a cantilever length

  6. The Lactamase Engineering Database: a critical survey of TEM sequences in public databases.

    Science.gov (United States)

    Thai, Quan Ke; Bös, Fabian; Pleiss, Jürgen

    2009-08-21

    TEM beta-lactamases are the main cause for resistance against beta-lactam antibiotics. Sequence information about TEM beta-lactamases is mainly found in the NCBI peptide database and TEM mutation table at http://www.lahey.org/Studies/temtable.asp. While the TEM mutation table is manually curated by experts in the lactamase field, who guarantee reliable and consistent information, the rapidly growing sequence and annotation information from the NCBI peptide database is sometimes inconsistent. Therefore, the Lactamase Engineering Database has been developed to collect the TEM beta-lactamase sequences from the NCBI peptide database and the TEM mutation table, systematically compare sequence information and naming, identify inconsistencies, and thus provide a versatile tool for reconciliation of data and for an investigation of the sequence-function relationship. The LacED currently provides 2399 sequence entries and 37 structure entries. Sequence information on 150 different TEM beta-lactamases was derived from the TEM mutation table which provides a unique number to each protein classified as TEM beta-lactamase. 293 TEM-like proteins were found in the NCBI protein database, but only 113 TEM beta-lactamase were common to both data sets. The 180 TEM beta-lactamases from the NCBI protein database which have not yet been assigned to a TEM number fall in three classes: (1) 89 proteins from microbial organisms and 35 proteins from cloning or expression vectors had a new mutation profile; (2) 55 proteins had inconsistent annotation in terms of TEM assignment or reported mutation profile; (3) 39 proteins are fragments. The LacED is web accessible at http://www.LacED.uni-stuttgart.de and contains multisequence alignments, structure information and reconciled annotation of TEM beta-lactamases. The LacED is weekly updated and supplies all data for download. The Lactamase Engineering Database enables a systematic analysis of TEM beta-lactamase sequence and annotation data from

  7. Sub-surface microstructure of single and polycrystalline tungsten after high flux plasma exposure studied by TEM

    Energy Technology Data Exchange (ETDEWEB)

    Dubinko, A., E-mail: adubinko@sckcen.be [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Terentyev, D. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Bakaeva, A. [Institute for Nuclear Material Sciences, SCK-CEN, 2400 Mol (Belgium); Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Hernández-Mayoral, M. [Division of Materials, CIEMAT, 28040 Madrid (Spain); De Temmerman, G. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St Paul-lez-Durance Cedex (France); Buzi, L. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany); Noterdaeme, J.-M. [Department of Applied Physics, Ghent University, 9000 Ghent (Belgium); Unterberg, B. [Forschungszentrum Julich, Inst. Energie & Klimaforsch Plasmaphys, D-52425 Julich (Germany)

    2017-01-30

    Highlights: • Plasma exposure induces dislocation-dominated microstructure as indicated by TEM. • Plasma exposure increases surface dislocation density by an order of magnitude in the polycrystalline tungsten. • Intensive dislocation-grain boundary interaction observed in polycrystalline tungsten. • Dislocation loops are observed in both polycrystalline and single crystal tungsten. - Abstract: We have performed high flux plasma exposure of tungsten and subsequent microstructural characterization using transmission electron microscopy (TEM) techniques. The aim was to reveal the nanometric features in the sub-surface region as well as to compare the microstructural evolution in tungsten single crystal and ITER-relevant specification. In both types of samples, TEM examination revealed the formation of a dense dislocation network and dislocation tangles. The estimated dislocation density in the sub-surface region was of the order of 10{sup 14} m{sup −2} and it gradually decreased with a depth position of the examined sample. Besides individual dislocation lines, networks and tangles, the interstitial dislocation loops have been observed in all examined samples only after the exposure. Contrary to that, examination of the pristine single crystal W and backside of the plasma-exposed samples did not reveal the presence of dislocation loops and tangles. This clearly proves that high flux plasma exposure induces severe plastic deformation in the sub-surface region irrespective of the presence of initial dislocations and sub-grains, and the formation of dislocation tangles, networks and interstitial loops is a co-product of thermal stress and intensive plasma particles uptake.

  8. A study on the microstructure of Pt/TaN/Si films by high resolution TEM analysis

    CERN Document Server

    Cho, K N; Oh, J E; Park, C S; Lee, S I; Lee, M Y

    1998-01-01

    The microstructure change of Pt/amorphous TaN/Si films after various heat treatments has been investigated by high resolution transmission electron microscopy (HR-TEM) analysis. TaN thin films are deposited by remote plasma metalorganic chemical vapor deposition (RP-MOCVD) using pentakis-dimethyl-amino-tantalum (PDMATa) and radical sources, hydrogen and ammonia plasma. Deposited TaN thin film shows excellent barrier properties such as good resistance against oxidation after post-heat treatment at high temperature. In the case of hydrogen plasma, however, diffusion of Pt into TaN layer was observed, which was caused by the out-diffusion of carbon through the grain boundaries of Pt. In the case of ammonia plasma, the formation of thin oxide layer at the Pt/TaN interface was observed.

  9. In-situ TEM studies of nanostructured thermoelectric materials: An application to Mg-doped Zn4Sb3 alloy.

    Science.gov (United States)

    Ngo, Duc-The; Le, Hung Thanh; Ngo, Nong Van

    2017-10-09

    We demonstrate an advanced approach using advanced in-situ transmission electron microscopy (TEM) to understand the interplay between nanostructures and thermoelectric (TE) properties of high-performance Mg-doped Zn4Sb3 TE system. With the technique, microstructure and crystal evolutions of TE material have been dynamically captured as a function of temperature from 300 K to 573 K. On heating, we have observed clearly precipitation and growth of a Zn-rich secondary phase as nanoinclusions in the matrix of primary Zn4Sb3 phase. Elemental mapping by STEM-EDX spectroscopy reveals enrichment of Zn in the secondary Zn6Sb5 nanoinclusions during the thermal processing without decomposition observed. Such nanostructure strongly enhances the phonon scattering resulting in the decrease in the thermal conductivity leading to a zT value of 1.4 at 718 K. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Problems at the Leading Edge of Space Weathering as Revealed by TEM Combined with Surface Science Techniques

    Science.gov (United States)

    Christoffersen, R.; Dukes, C. A.; Keller, L. P.; Rahman, Z.; Baragiola, R. A.

    2015-01-01

    Both transmission electron micros-copy (TEM) and surface analysis techniques such as X-ray photoelectron spectroscopy (XPS) were instrumen-tal in making the first characterizations of material generated by space weathering in lunar samples [1,2]. Without them, the nature of nanophase metallic Fe (npFe0) correlated with the surface of lunar regolith grains would have taken much longer to become rec-ognized and understood. Our groups at JSC and UVa have been using both techniques in a cross-correlated way to investigate how the solar wind contributes to space weathering [e.g., 3]. These efforts have identified a number of ongoing problems and knowledge gaps. Key insights made by UVa group leader Raul Barag-iola during this work are gratefully remembered.

  11. SEM, TEM, and IHC Analysis of the Sinus Node and Its Implications for the Cardiac Conduction System

    Directory of Open Access Journals (Sweden)

    D. Mandrioli

    2013-01-01

    Full Text Available More than 100 years after the discovery of the sinus node (SN by Keith and Flack, the function and structure of the SN have not been completely established yet. The anatomic architecture of the SN has often been described as devoid of an organized structure; the origin of the sinus impulse is still a matter of debate, and a definite description of the long postulated internodal specialized tract conducting the impulse from the SN to the atrioventricular node (AVN is still missing. In our previously published study, we proposed a morphologically ordered structure for the SN. As a confirmation of what was presented then, we have added the results of additional observations regarding the structural particularities of the SN. We investigated the morphology of the sinus node in the human hearts of healthy individuals using histochemical, immunohistochemical, optical, and electron microscopy (SEM, TEM. Our results confirmed that the SN presents a previously unseen highly organized architecture.

  12. Report on the Installation and Preparedness of a Protochips Fusion in-situ Heating Holder for TEM

    Energy Technology Data Exchange (ETDEWEB)

    Edmondson, Philip D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-03-01

    This brief report documents the procurement and installation of a Protochips Fusion (formerly Aduro) high-temperature, high stability transmission electron microscopy (TEM) specimen holder that allows for the high spatial resolution characterization of material specimens at high temperature in situ of an electron microscope. This specimen holder was specifically procured for use with The FEI Talos F200X Scanning/Transmission Electron Microscope (STEM) in Oak Ridge National Laboratory’s (ORNL’s) Low Activation Materials Development and Analysis (LAMDA) Laboratory. The Protochips Fusion holder will enable high-resolution structural and chemical analysis of irradiated materials at high temperature, becoming a unique capability worldwide, and would encourage high-quality in situ experiments to be conducted on irradiated materials.

  13. Contribution of PBP3 Substitutions and TEM-1, TEM-15, and ROB-1 Beta-Lactamases to Cefotaxime Resistance in Haemophilus influenzae and Haemophilus parainfluenzae.

    Science.gov (United States)

    Søndergaard, Annette; Nørskov-Lauritsen, Niels

    2016-06-01

    To investigate the relative contributions of naturally occurring penicillin-binding protein 3 (PBP3) substitutions, and TEM-1, TEM-15, and ROB-1 beta-lactamases on resistance to a third-generation cephalosporin in Haemophilus influenzae and Haemophilus parainfluenzae. The minimum inhibitory concentration (MIC) of cefotaxime (CTX) was assessed after transformation with PCR-amplified ftsI genes expressing altered PBP3 and/or small plasmids encoding beta-lactamases into an isogenic environment of H. influenzae and H. parainfluenzae. Group III PBP3, comprising substitutions N526K, S385T, and L389F, conferred CTX resistance to H. influenzae according to EUCAST interpretative criteria. Group III-like PBP3, comprising substitutions N526H and S385T, increased the CTX MIC of H. parainfluenzae ninefold, but the level did not transgress the resistance breakpoint. Production of TEM-15 beta-lactamase conferred CTX resistance on both H. influenzae and H. parainfluenzae. A nitrocefin hydrolysis assay showed TEM-15 to be a less efficient enzyme compared to TEM-1. TEM-15 and PBP3 substitutions impose an additive effect on resistance to third-generation cephalosporins in both H. influenzae and H. parainfluenzae. The effect of PBP3 substitutions on beta-lactam resistance in H. parainfluenzae can be addressed by transfer of ftsI genes in vitro.

  14. Transmission electron microscopy of polymer blends and block copolymers

    Science.gov (United States)

    Gomez, Enrique Daniel

    Transmission electron microscopy (TEM) of soft matter is a field that warrants further investigation. Developments in sample preparation, imaging and spectroscopic techniques could lead to novel experiments that may further our understanding of the structure and the role structure plays in the functionality of various organic materials. Unlike most hard materials, TEM of organic molecules is limited by the amount of radiation damage the material can withstand without changing its structure. Despite this limitation, TEM has been and will be a powerful tool to study polymeric materials and other soft matter. In this dissertation, an introduction of TEM for polymer scientists is presented. The fundamentals of interactions of electrons with matter are described using the Schrodinger wave equation and scattering cross-sections to fully encompass coherent and incoherent scattering. The intensity, which is the product of the wave function and its complex conjugate, shows no perceptible change due to the sample. Instead, contrast is generated through the optical system of the microscope by removing scattered electrons or by generating interference due to material-induced phase changes. Perhaps the most challenging aspect of taking TEM images, however, is sample preparation, because TEM experiments require materials with approximately 50 nm thickness. Although ultramicrotomy is a well-established powerful tool for preparing biological and polymeric sections for TEM, the development of cryogenic Focused Ion Beam may enable unprecedented cross-sectional TEM studies of polymer thin films on arbitrary substrates with nanometer precision. Two examples of TEM experiments of polymeric materials are presented. The first involves quantifying the composition profile across a lamellar phase obtained in a multicomponent blend of saturated poly(butadiene) and poly(isobutylene), stabilized by a saturated poly(butadiene) copolymer serving as a surfactant, using TEM and self

  15. Fine structure of bacterial adhesion to the epithelial cell membranes of the filiform papillae of tongue and palatine mucosa of rodents: a morphometric, TEM, and HRSEM study.

    Science.gov (United States)

    Watanabe, Ii-Sei; Ogawa, Koichi; Cury, Diego Pulzatto; Dias, Fernando José; Sosthenes, Marcia Consentino Kronka; Issa, João Paulo Mardegan; Iyomasa, Mamie Mizusaki

    2013-12-01

    The palatine mucosa and filiform papillae of the dorsal tongue mucosae of rodents were examined using transmission electron microscopy (TEM) and high resolution scanning electron microscopy (HRSEM). In the HRSEM method, the samples were fixed in 2% osmium tetroxide, dehydrated in alcohol, critical point-dried, and coated with gold-palladium. In addition, the HRSEM technique was used for morphometric analysis (length, width, and length/width ratio of cocci and bacilli). For the TEM method, the tissues were fixed in modified Karnovsky solution (2.5% glutaraldehyde, 2% formalin in 0.1M sodium phosphate buffer, pH 7.4) and embedded in Spurr resin. The results demonstrated that there are thick polygonal keratinized epithelial cells where groups of bacteria are revealed in three-dimensional images on the surface of filiform papillae in these animals. The bacterial membranes are randomly attached to the microplicae surface of epithelial cells. Morphometrics showed higher values of length and width of cocci in newborn (0 day) as compared to newborn (7 days) and adults animals, the bacilli showed no differences in these measurements. At high magnification, the TEM images revealed the presence of glycocalyx microfilaments that constitute a fine adhesion area between bacterial membranes and the membranes of epithelial microplicae cells. In conclusion, the present data revealed the fine fibrillar structures of bacteria that facilitate adhesion to the epithelial cell membranes of the oral cavity and morphometric changes in newborn (0 day) rats as compared with other periods. Copyright © 2013 Wiley Periodicals, Inc.

  16. Streamlined embedding of cell monolayers on gridded glass-bottom imaging dishes for correlative light and electron microscopy.

    Science.gov (United States)

    Hanson, Hugo H; Reilly, James E; Lee, Rebecca; Janssen, William G; Phillips, Greg R

    2010-12-01

    Correlative light and electron microscopy (CLEM) has facilitated study of intracellular trafficking. Routine application of CLEM would be advantageous for many laboratories but previously described techniques are particularly demanding, even for those with access to laser scanning confocal microscopy (LSCM) and transmission electron microscopy (TEM). We describe streamlined methods for TEM of green fluorescent protein (GFP)-labeled organelles after imaging by LSCM using gridded glass bottom imaging dishes. GFP-MAP 1A/1B LC3 (GFP-LC3) transfected cells were treated with rapamycin, fixed and imaged by LSCM. Confocal image stacks were acquired enabling full visualization of each GFP-LC3 labeled organelle. After LSCM, cells were embedded for TEM using a simplified two step method that stabilizes the glass bottom such that the block can be separated from the glass by mild heating. All imaging and TEM processing are performed in the same dish. The LSCM imaged cells were relocated on the block and serial sectioned. Correlation of LSCM, DIC, and TEM images was facilitated by cellular landmarks. All GFP labeled structures were successfully reidentified and imaged by serial section TEM. This method could make CLEM more accessible to nonspecialized laboratories with basic electron microscopy expertise and could be used routinely to confirm organelle localization of fluorescent puncta.

  17. TEM studies of laterally overgrown GaN layers grown in polar and non-polar directions

    Science.gov (United States)

    Liliental-Weber, Z.; Zakharov, D.; Wagner, B.; Davis, R. F.

    2006-02-01

    Transmission electron microscopy (TEM) was used to study pendeo-epitaxial GaN layers grown on polar and non-polar 4H SiC substrates. The structural quality of the overgrown layers was evaluated using a number of TEM methods. Growth of pendeo-epitaxial layers on polar substrates leads to better structural quality of the overgrown areas, however edge-on dislocations are found at the meeting fronts of two wings. Some misorientation between the "seed" area and wing area was detected by Convergent Beam Electron Diffraction. Growth of pendeo-epitaxial layers on non-polar substrates is more difficult. Two wings on the opposite site of the seed area grow in two different polar directions with different growth rates and wings grown with Ga polarity are 17 times wider than wings grown with N-polarity, making coalescence of these layers difficult. Most dislocations in a wing grown with Ga polarity bend in a direction parallel to the substrate, but some of them also propagate to the sample surface. Stacking faults formed on the c-plane and prismatic plane occasionally were found in the wings. Some misorientation between the wings and seed was detected using Large Angle Convergent Beam Diffraction.

  18. Recombination-related properties of a-screw dislocations in GaN: A combined CL, EBIC, TEM study

    Energy Technology Data Exchange (ETDEWEB)

    Medvedev, O. S., E-mail: o.s.medvedev@spbu.ru; Mikhailovskii, V. Yu. [V.A. Fok Institute of Physics, St. Petersburg State University (Russian Federation); IRC for Nanotechnology, Research Park, St.-Petersburg State University (Russian Federation); Vyvenko, O. F.; Bondarenko, A. S.; Ubyivovk, E. V. [V.A. Fok Institute of Physics, St. Petersburg State University (Russian Federation); Peretzki, P.; Seibt, M. [IV. Physikalisches Institut Georg-August Universität Göttingen (Germany)

    2016-06-17

    Cathodoluminescence (CL), electron beam current (EBIC) and transmission electron microscopy (TEM) techniques have been applied to investigate recombination properties and structure of freshly introduced dislocations in low-ohmic GaN crystals. It was confirmed that the only a-screw dislocations exhibited an intense characteristic dislocation-related luminescence (DRL) which persisted up to room temperature and was red-shifted by about 0.3 eV with respect to the band gap energy not only in HVPE but also in MOCVD grown samples. EBIC contrast of the dislocations was found to be temperature independent indicating that the dislocation-related recombination level is situated below 200 meV with respect of conduction band minimum. With the increasing of the magnification of the dislocation TEM cross-sectional images they were found to disappear, probably, due to the recombination enhanced dislocation glide (REDG) under electron beam exposure which was immediately observed in CL investigations on a large scale. The stacking fault ribbon in the core of dissociated a-screw dislocation which form a quantum well for electrons was proposed to play an important role both in DRL spectrum formation and in REDG.

  19. Studying Dynamic Processes of Nano-sized Objects in Liquid using Scanning Transmission Electron Microscopy

    OpenAIRE

    Hermannsd?rfer, Justus; de Jonge, Niels

    2017-01-01

    Samples fully embedded in liquid can be studied at a nanoscale spatial resolution with Scanning Transmission Electron Microscopy (STEM) using a microfluidic chamber assembled in the specimen holder for Transmission Electron Microscopy (TEM) and STEM. The microfluidic system consists of two silicon microchips supporting thin Silicon Nitride (SiN) membrane windows. This article describes the basic steps of sample loading and data acquisition. Most important of all is to ensure that the liquid c...

  20. Direct observation of defect structure in protein crystals by atomic force and transmission electron microscopy.

    OpenAIRE

    Devaud, G; Furcinitti, P S; Fleming, J.C.; Lyon, M K; Douglas, K

    1992-01-01

    We have examined the structure of S-layers isolated from Sulfolobus acidocaldarius using atomic force microscopy (AFM) and transmission electron microscopy (TEM). From the AFM images, we were able to directly observe individual dimers of the crystal, defects in the crystal structure, and twin boundaries. We have identified two types of boundaries, one defined by a mirror plane and the other by a glide plane. This work shows that twin boundaries are highly structured regions that are directly ...

  1. Electron microscopy methods in studies of cultural heritage sites

    Energy Technology Data Exchange (ETDEWEB)

    Vasiliev, A. L., E-mail: a.vasiliev56@gmail.com; Kovalchuk, M. V.; Yatsishina, E. B. [National Research Centre “Kurchatov Institute” (Russian Federation)

    2016-11-15

    The history of the development and application of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray microanalysis (EDXMA) in studies of cultural heritage sites is considered. In fact, investigations based on these methods began when electron microscopes became a commercial product. Currently, these methods, being developed and improved, help solve many historical enigmas. To date, electron microscopy combined with microanalysis makes it possible to investigate any object, from parchment and wooden articles to pigments, tools, and objects of art. Studies by these methods have revealed that some articles were made by ancient masters using ancient “nanotechnologies”; hence, their comprehensive analysis calls for the latest achievements in the corresponding instrumental methods and sample preparation techniques.

  2. Light Sheet Fluorescence Microscopy

    Science.gov (United States)

    Santi, Peter A.

    2011-01-01

    Light sheet fluorescence microscopy (LSFM) functions as a non-destructive microtome and microscope that uses a plane of light to optically section and view tissues with subcellular resolution. This method is well suited for imaging deep within transparent tissues or within whole organisms, and because tissues are exposed to only a thin plane of light, specimen photobleaching and phototoxicity are minimized compared to wide-field fluorescence, confocal, or multiphoton microscopy. LSFMs produce well-registered serial sections that are suitable for three-dimensional reconstruction of tissue structures. Because of a lack of a commercial LSFM microscope, numerous versions of light sheet microscopes have been constructed by different investigators. This review describes development of the technology, reviews existing devices, provides details of one LSFM device, and shows examples of images and three-dimensional reconstructions of tissues that were produced by LSFM. PMID:21339178

  3. Multimodal hyperspectral optical microscopy

    Science.gov (United States)

    Novikova, Irina V.; Smallwood, Chuck R.; Gong, Yu; Hu, Dehong; Hendricks, Leif; Evans, James E.; Bhattarai, Ashish; Hess, Wayne P.; El-Khoury, Patrick Z.

    2017-11-01

    We describe a unique approach to hyperspectral optical microscopy, herein achieved by coupling a hyperspectral imager to various optical microscopes. Hyperspectral fluorescence micrographs of isolated fluorescent beads are first employed to ensure spectral calibration of our detector and to gauge the attainable spatial resolution of our measurements. Different science applications of our instrument are then described. Spatially over-sampled absorption spectroscopy of a single lipid (18:1 Liss Rhod PE) layer reveals that optical densities on the order of 10-3 can be resolved by spatially averaging the recorded optical signatures. This is followed by three applications in the general areas of plasmonics and bioimaging. Notably, we deploy hyperspectral absorption microscopy to identify and image pigments within a simple biological system, namely, a single live Tisochrysis lutea cell. Overall, this work paves the way for multimodal spectral imaging measurements spanning the realms of several scientific disciplines.

  4. The mandibular ridge oral mucosa model of stromal influences on the endothelial tip cells: an immunohistochemical and TEM study.

    Science.gov (United States)

    Rusu, Mugurel Constantin; Didilescu, Andreea Cristiana; Stănescu, Ruxandra; Pop, Florinel; Mănoiu, Valentina Mariana; Jianu, Adelina Maria; Vâlcu, Marek

    2013-02-01

    This study aimed to evaluate by immunohistochemistry and transmission electron microscopy (TEM) the morphological features of the oral mucosa endothelial tip cells (ETCs) and to determine the immune and ultrastructural patterns of the stromal nonimmune cells which could influence healing processes. Immune labeling was performed on bioptic samples obtained from six edentulous patients undergoing surgery for dental implants placement; three normal samples were collected from patients prior to the extraction of the third mandibular molar. The antibodies were tested for CD34, CD117(c-kit), platelet derived growth factor receptor-alpha (PDGFR-α), Mast Cell Tryptase, CD44, vimentin, CD45, CD105, alpha-smooth muscle actin, FGF2, Ki67. In light microscopy, while stromal cells (StrCs) of the reparatory and normal oral mucosa, with a fibroblastic appearance, were found positive for a CD34/CD44/CD45/CD105/PDGFR-α/vimentin immune phenotype, the CD117/c-kit labeling led to a positive stromal reaction only in the reparatory mucosa. In TEM, non-immune StrCs presenting particular ultrastructural features were identified as circulating fibrocytes (CFCs). Within the lamina propria CFCs were in close contact with ETCs. Long processes of the ETCs were moniliform, and hook-like collaterals were arising from the dilated segments, suggestive for a different stage migration. Maintenance and healing of oral mucosa are so supported by extensive processes of angiogenesis, guided by ETCs that, in turn, are influenced by the CFCs that populate the stromal compartment both in normal and reparatory states. Therefore, CFCs could be targeted by specific therapies, with pro- or anti-angiogenic purposes. Copyright © 2012 Wiley Periodicals, Inc.

  5. OSCE vs. TEM: Different Approaches to Assess Clinical Skills of Nursing Students.

    Science.gov (United States)

    Jelly, Prasuna; Sharma, Rakesh

    2017-01-01

    Nurses are trained with specific clinical skills, and objective structured clinical examination (OSCE) could be a better approach to assess clinical skills of nursing students. A comparative study was conducted by observational checklist regarding antenatal care and opinionnaire on the usefulness of OSCE and tradition evaluation method (TEM) was used to assess the clinical skills and to get opinion. The mean score of OSCE was more than TEM and the difference was statistically significant (P < 0.001). The opinion of students regarding the usefulness of OSCE was higher than TEM. The study concluded that implementing OSCE will overweigh the advantages of the TEM.

  6. Comparative studies of thin film growth on aluminium by AFM, TEM and GDOES characterization

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Jiantao, E-mail: alexanderinmanchester@gmail.com; Thompson, George E.

    2016-07-30

    Highlights: • Coating initiation was evidenced after conversion treatment for only 30 s and the uniform cross section revealed a chemical deposition process of electrolyte anions on aluminium. • A proceeding process of aluminium dissolution during conversion treatment was found for the first time, indicating non-inhibitive kinetics of anodic reactions. • Coating growth on aluminium was determined by the availability of electrolyte anions and the prolonged conversion treatment crated a significant concentration gradient to limit growth. • Coating shrinkage either in the microscope or after post-coating treatment in the air was clarified, especially for the coating after prolonged conversion treatments. - Abstract: In this present study, comparative studies of trivalent chromium conversion coating formation, associated with aluminium dissolution process, have been investigated using atomic force microscopy (AFM), transmission electron microscopy (TEM) and glow-discharge optical emission spectroscopy (GDOES). High-resolution electron micrographs revealed the evident and uniform coating initiation on the whole surface after conversion treatment for only 30 s, although a network of metal ridges was created by HF etching pre-treatment. In terms of conversion treatment process on electropolished aluminium, constant kinetics of coating growth, ∼0.30 ± 0.2 nm/s, were found after the prolonged conversion treatment for 600 s. The availability of electrolyte anions for coating deposition determined the growth process. Simultaneously, a proceeding process of aluminium dissolution during conversion treatment, of ∼0.11 ± 0.02 nm/s, was found for the first time, indicating constant kinetics of anodic reactions. The distinct process of aluminium consumption was assigned with loss of corrosion protection of the deposited coating material as evidenced in the electrochemical impedance spectroscopy. Based on the present data, a new mechanism of coating growth on aluminium

  7. Electron microscopy of viruses.

    Science.gov (United States)

    Laue, Michael

    2010-01-01

    Electron microscopy is widely used in virology because viruses are generally too small for a direct inspection by light microscopy. Analysis of virus morphology is necessary in many circumstances, e.g., for the diagnosis of a virus in particular clinical situations or the analysis of virus entry and assembly. Moreover, quality control of virus particle integrity is required if a virus is propagated in cell culture, particularly if the virus genome has changed. In most cases already the basic methodology for transmission electron microscopy, i.e., negative staining and ultrathin sectioning, is sufficient to give relevant information on virus ultrastructure. This chapter gives detailed information on the principles of these basic methodologies and provides simple but reliable protocols for a quick start. Moreover, the description of standard protocols for negative staining and ultrathin sectioning are supplemented by protocols on immuno-negative staining and rapid ultrathin sectioning. Finally, principles of methods for an extended ultrastructural research using more elaborate techniques, such as cryotechniques or methods to reveal the three-dimensional virus architecture, are briefly reviewed. Copyright © 2010 Elsevier Inc. All rights reserved.

  8. Deep Learning Microscopy

    KAUST Repository

    Rivenson, Yair

    2017-05-12

    We demonstrate that a deep neural network can significantly improve optical microscopy, enhancing its spatial resolution over a large field-of-view and depth-of-field. After its training, the only input to this network is an image acquired using a regular optical microscope, without any changes to its design. We blindly tested this deep learning approach using various tissue samples that are imaged with low-resolution and wide-field systems, where the network rapidly outputs an image with remarkably better resolution, matching the performance of higher numerical aperture lenses, also significantly surpassing their limited field-of-view and depth-of-field. These results are transformative for various fields that use microscopy tools, including e.g., life sciences, where optical microscopy is considered as one of the most widely used and deployed techniques. Beyond such applications, our presented approach is broadly applicable to other imaging modalities, also spanning different parts of the electromagnetic spectrum, and can be used to design computational imagers that get better and better as they continue to image specimen and establish new transformations among different modes of imaging.

  9. CryoTEM as an Advanced Analytical Tool for Materials Chemists.

    Science.gov (United States)

    Patterson, Joseph P; Xu, Yifei; Moradi, Mohammad-Amin; Sommerdijk, Nico A J M; Friedrich, Heiner

    2017-07-18

    Morphology plays an essential role in chemistry through the segregation of atoms and/or molecules into different phases, delineated by interfaces. This is a general process in materials synthesis and exploited in many fields including colloid chemistry, heterogeneous catalysis, and functional molecular systems. To rationally design complex materials, we must understand and control morphology evolution. Toward this goal, we utilize cryogenic transmission electron microscopy (cryoTEM), which can track the structural evolution of materials in solution with nanometer spatial resolution and a temporal resolution of materials. These three different research areas are at the heart of our approach to materials chemistry where we take inspiration from the myriad examples of complex materials in Nature. Biological materials are formed using a limited number of chemical components and under ambient conditions, and their formation pathways were refined during biological evolution by enormous trial and error approaches to self-organization and biomineralization. By combining the information on what is possible in nature and by focusing on a limited number of chemical components, we aim to provide an essential insight into the role of structure evolution in materials synthesis. Bone, for example, is a hierarchical and hybrid material which is lightweight, yet strong and hard. It is formed by the hierarchical self-assembly of collagen into a macromolecular template with nano- and microscale structure. This template then directs the nucleation and growth of oriented, nanoscale calcium phosphate crystals to form the composite material. Fundamental insight into controlling these structuring processes will eventually allow us to design such complex materials with predetermined and potentially unique properties.

  10. Comparison of ultramicrotomy and focused-ion-beam for the preparation of TEM and STEM cross section of organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Corazza, Michael, E-mail: michael.corazza@gmail.com [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Simonsen, Søren B. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark); Gnaegi, Helmut [Diatome Ltd., Biel-Bienne (Switzerland); Thydén, Karl T.S.; Krebs, Frederik C.; Gevorgyan, Suren A. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde (Denmark)

    2016-12-15

    Highlights: • Comparison of flexible solar cell sections prepared by ultramicrotomy and by FIB. • Energy filtered TEM analysis of phase separation in the P3HT:PCBM active layer. • Imaging of aging effects on solar cell cross section prepared by ultramicrotomy. • Ultramicrotomy provides great details while FIB better preserves the structure. - Abstract: The challenge of preparing cross sections of organic photovoltaics (OPV) suitable for transmission electron microscopy (TEM) and scanning TEM (STEM) is addressed. The samples were polymer solar cells fabricated using roll-to-roll (R2R) processing methods on a flexible polyethylene terephthalate (PET) substrate. Focused ion beam (FIB) and ultramicrotomy were used to prepare the cross sections. The differences between the samples prepared by ultramicrotomy and FIB are addressed, focusing on the advantages and disadvantages of each technique. The sample prepared by ultramicrotomy yielded good resolution, enabling further studies of phase separation of P3HT:PCBM by means of energy filtered TEM (EFTEM). The sample prepared by FIB shows good structure preservation, but reduced resolution due to non-optimal thicknesses achieved after treatment. Degradation studies of samples prepared by ultramicrotomy are further discussed, which reveal particular effects of the ISOS-L-3 aging test (85 °C, 50% R.H., 0.7 Sun) onto the sample, especially pronounced in the silver layer.

  11. Local probing of structure and property in dimensionally confined amorphous and crystalline structures by S/TEM

    Science.gov (United States)

    Yan, Aiming

    The characterization of materials' microstructure has been brought up to a new level since the invention and broad application of transmission electron microscope (TEM) thanks to the high-energy electron beam source which guarantees an unsurpassable spatial resolution and theoretical study of interaction between electron and matter. The advent of nano-world has imposed an urgent request to characterize nano-assemblies in nano- or even sub-nano-scale and scanning transmission electron microscopy (STEM) which typically utilizes an electron probe with a size of 1nm or even smaller has found its unique advantage to unravel the local structure, chemical and physical properties of these emerging nanostructures. Dimensionally constrained nanostructures such as thin films and nanopatterned systems have attracted people's attention for decades due to their novel chemical and physical properties and popularity in energy storage, biological integration and etc. This dissertation focuses on the unique characterization capability of S/TEM to study the local order in amorphous transparent conducting oxide thin films, disordering in 2-D layered materials, localized surface plasmons in nanoporous gold patterns on 2-D layered structures and crystallization process in dimensionally and spatially constrained oxide nanopatterns observed by in-situ TEM. Electron diffraction and x-ray diffraction are commonly used techniques to study the crystallinity in a certain material - crystalline or amorphous. In amorphous materials which lack long-range order, normal electron diffraction and x-ray diffraction techniques won't be able to extract any useful information regarding the ordering or disordering in the materials. We have developed a unique set of electron diffraction methods in both TEM and STEM, combined with density functional theory molecular dynamics of liquid quench to study the short-range (< 1 nm) and medium-range order (between 1 nm and 3 nm) in amorphous transparent oxide films

  12. Assessment of the contribution of electron microscopy to nanoparticle characterization sampled with two cascade impactors.

    Science.gov (United States)

    Noël, Alexandra; L'Espérance, Gilles; Cloutier, Yves; Plamondon, Philippe; Boucher, Julie; Philippe, Suzanne; Dion, Chantal; Truchon, Ginette; Zayed, Joseph

    2013-01-01

    This study assessed the contribution of electron microscopy to the characterization of nanoparticles and compared the degree of variability in sizes observed within each stage when sampled by two cascade impactors: an Electrical Low Pressure Impactor (ELPI) and a Micro-Orifice Uniform Deposit Impactor (MOUDI). A TiO(2) nanoparticle (5 nm) suspension was aerosolized in an inhalation chamber. Nanoparticles sampled by the impactors were collected on aluminum substrates or TEM carbon-coated copper grids using templates, specifically designed in our laboratories, for scanning and transmission electron microscopy (SEM, TEM) analysis, respectively. Nanoparticles were characterized using both SEM and TEM. Three different types of diameters (inner, outer, and circular) were measured by image analysis based on count and volume, for each impactor stage. Electron microscopy, especially TEM, is well suited for the characterization of nanoparticles. The MOUDI, probably because of the rotation of its collection stages, which can minimize the resuspension of particles, gave more stable results and smaller geometric standard deviations per stage. Our data suggest that the best approach to estimate particle size by electron microscopy would rely on geometric means of measured circular diameters. Overall, the most reliable data were provided by the MOUDI and the TEM sampling technique on carbon-coated copper grids for this specific experiment. This study indicates interesting findings related to the assessment of impactors combined with electron microscopy for nanoparticle characterization. For future research, since cascade impactors are extensively used to characterize nano-aerosol exposure scenarios, high-performance field emission scanning electron microscopy (FESEM) should also be considered.

  13. TEM Examination of Shock Veins in Ordinary Chondrites

    Science.gov (United States)

    Lingemann, C. M.; Langenhorst, F.; Stoffler, D.

    1995-09-01

    Introduction: As part of a research project on shock metamorphism of chondrites [1] we studied shock veins in different L-chondrites to understand their formation conditions. These thin shock veins (>20 micrometers thickness) have been found in the meteorites L5-6-Acfer 040, L6-Coorara, L6-Johnson City and L6-Tenham and were studied in detail by analytical transmission electron microscopy (ATEM). Texture. Shock veins consist of a fine-grained opaque matrix with embedded large fragments of the host chondrite. High-pressure polymorphs of olivine (ringwoodite and wadsleyite) and enstatite (majorite), which are clear indicators of strong shock metamorphism [1], are present in both matrix and fragments. In the matrix, majorite and, to a minor extent, ringwoodite coexist with globules of Fe-Ni alloy and troilite (ringwoodite and majorite occur as polycrystalline aggregates of tiny crystals (Ringwoodite shows generally a high density of stacking faults parallel to 110 planes. These stacking faults are interpreted as growth defects due to rapid cooling [2]. Majorite is defect-free. Chemistry. Ringwoodite in fragments is chemically less homogeneous and tends to a higher FeO-content than olivine in the host chondrite [3, 4]. A tendency to chemical heterogeneity has also been detected for majorite in fragments. The composition of the majorite in the matrix is distinctly heterogeneous and differs systematically from that of the enstatite, because it shows a distinct enrichment in Al, Mg, Ca, Na and a significant depletion in Si, Mn and especially in Fe, which is up to 50% lower than in the primary enstatite. Discussion. Chemical heterogeneity and small grain sizes of high-pressure phases as well as presence of Fe-Ni alloy and troilite in the form of globules indicates that shock veins represent quenched melts. The high-pressure phases are interpreted as crystallization products of these melts. The localized temperature excursions result probably from friction of the meteoritic

  14. In Situ Electron Microscopy of Lactomicroselenium Particles in Probiotic Bacteria

    Directory of Open Access Journals (Sweden)

    Gabor Nagy

    2016-06-01

    Full Text Available Electron microscopy was used to test whether or not (a in statu nascendi synthesized, and in situ measured, nanoparticle size does not differ significantly from the size of nanoparticles after their purification; and (b the generation of selenium is detrimental to the bacterial strains that produce them. Elemental nano-sized selenium produced by probiotic latic acid bacteria was used as a lactomicroselenium (lactomicroSel inhibitor of cell growth in the presence of lactomicroSel, and was followed by time-lapse microscopy. The size of lactomicroSel produced by probiotic bacteria was measured in situ and after isolation and purification. For these measurements the TESLA BS 540 transmission electron microscope was converted from analog (aTEM to digital processing (dTEM, and further to remote-access internet electron microscopy (iTEM. Lactobacillus acidophilus produced fewer, but larger, lactomicroSel nanoparticles (200–350 nm than Lactobacillus casei (L. casei, which generated many, smaller lactomicroSel particles (85–200 nm and grains as a cloudy, less electrodense material. Streptococcus thermophilus cells generated selenoparticles (60–280 nm in a suicidic manner. The size determined in situ in lactic acid bacteria was significantly lower than those measured by scanning electron microscopy after the isolation of lactomicroSel particles obtained from lactobacilli (100–500 nm, but higher relative to those isolated from Streptococcus thermopilus (50–100 nm. These differences indicate that smaller lactomicroSel particles could be more toxic to the producing bacteria themselves and discrepancies in size could have implications with respect to the applications of selenium nanoparticles as prebiotics.

  15. The importance of transmission electron microscopy analysis of spermatozoa: Diagnostic applications and basic research.

    Science.gov (United States)

    Moretti, Elena; Sutera, Gaetano; Collodel, Giulia

    2016-06-01

    This review is aimed at discussing the role of ultrastructural studies on human spermatozoa and evaluating transmission electron microscopy as a diagnostic tool that can complete andrology protocols. It is clear that morphological sperm defects may explain decreased fertilizing potential and acquire particular value in the field of male infertility. Electron microscopy is the best method to identify systematic or monomorphic and non-systematic or polymorphic sperm defects. The systematic defects are characterized by a particular anomaly that affects the vast majority of spermatozoa in a semen sample, whereas a heterogeneous combination of head and tail defects found in variable percentages are typically non-systematic or polymorphic sperm defects. A correct diagnosis of these specific sperm alterations is important for choosing the male infertility's therapy and for deciding to turn to assisted reproduction techniques. Transmission electron microscopy (TEM) also represents a valuable method to explore the in vitro effects of different compounds (for example drugs with potential spermicidal activity) on the morphology of human spermatozoa. Finally, TEM used in combination with immunohistochemical techniques, integrates structural and functional aspects that provide a wide horizon in the understanding of sperm physiology and pathology. transmission electron microscopy: TEM; World Health Organization: WHO; light microscopy: LM; motile sperm organelle morphology examination: MSOME; intracytoplasmic morphologically selected sperm injection: IMSI; intracytoplasmic sperm injection: ICSI; dysplasia of fibrous sheath: DFS; primary ciliary dyskinesia: PCD; outer dense fibers: ODF; assisted reproduction technologies: ART; scanning electron microscopy: SEM; polyvinylpirrolidone: PVP; tert-butylhydroperoxide: TBHP.

  16. The potentials and challenges of electron microscopy in the study of atomic chains

    Science.gov (United States)

    Banhart, Florian; Torre, Alessandro La; Romdhane, Ferdaous Ben; Cretu, Ovidiu

    2017-04-01

    The article is a brief review on the potential of transmission electron microscopy (TEM) in the investigation of atom chains which are the paradigm of a strictly one-dimensional material. After the progress of TEM in the study of new two-dimensional materials, microscopy of free-standing one-dimensional structures is a new challenge with its inherent potentials and difficulties. In-situ experiments in the TEM allowed, for the first time, to generate isolated atomic chains consisting of metals, carbon or boron nitride. Besides having delivered a solid proof for the existence of atomic chains, in-situ TEM studies also enabled us to measure the electrical properties of these fundamental linear structures. While ballistic quantum conductivity is observed in chains of metal atoms, electrical transport in chains of sp1-hybridized carbon is limited by resonant states and reflections at the contacts. Although substantial progress has been made in recent TEM studies of atom chains, fundamental questions have to be answered, concerning the structural stability of the chains, bonding states at the contacts, and the suitability for applications in nanotechnology. Contribution to the topical issue "The 16th European Microscopy Congress (EMC 2016)", edited by Richard Brydson and Pascale Bayle-Guillemaud

  17. Correlative light- and electron microscopy with chemical tags.

    Science.gov (United States)

    Perkovic, Mario; Kunz, Michael; Endesfelder, Ulrike; Bunse, Stefanie; Wigge, Christoph; Yu, Zhou; Hodirnau, Victor-Valentin; Scheffer, Margot P; Seybert, Anja; Malkusch, Sebastian; Schuman, Erin M; Heilemann, Mike; Frangakis, Achilleas S

    2014-05-01

    Correlative microscopy incorporates the specificity of fluorescent protein labeling into high-resolution electron micrographs. Several approaches exist for correlative microscopy, most of which have used the green fluorescent protein (GFP) as the label for light microscopy. Here we use chemical tagging and synthetic fluorophores instead, in order to achieve protein-specific labeling, and to perform multicolor imaging. We show that synthetic fluorophores preserve their post-embedding fluorescence in the presence of uranyl acetate. Post-embedding fluorescence is of such quality that the specimen can be prepared with identical protocols for scanning electron microscopy (SEM) and transmission electron microscopy (TEM); this is particularly valuable when singular or otherwise difficult samples are examined. We show that synthetic fluorophores give bright, well-resolved signals in super-resolution light microscopy, enabling us to superimpose light microscopic images with a precision of up to 25 nm in the x-y plane on electron micrographs. To exemplify the preservation quality of our new method we visualize the molecular arrangement of cadherins in adherens junctions of mouse epithelial cells. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Electron beam fabrication and characterization of high- resolution magnetic force microscopy tips

    NARCIS (Netherlands)

    Ruhrig, M.; Rührig, M.; Porthun, S.; Porthun, S.; Lodder, J.C.; Mc vitie, S.; Heyderman, L.J.; Johnston, A.B.; Chapman, J.N.

    1996-01-01

    The stray field, magnetic microstructure, and switching behavior of high‐resolution electron beam fabricated thin film tips for magnetic force microscopy (MFM) are investigated with different imaging modes in a transmission electron microscope (TEM). As the tiny smooth carbon needles covered with a

  19. Precise and unbiased estimation of astigmatism and defocus in transmission electron microscopy

    NARCIS (Netherlands)

    Vulovic, M.; Franken, E.; Ravelli, R.B.G.; Van Vliet, L.J.; Rieger, B.

    2012-01-01

    Defocus and twofold astigmatism are the key parameters governing the contrast transfer function (CTF) in transmission electron microscopy (TEM) of weak phase objects. We present a new algorithm to estimate these aberrations and the associated uncertainties. Tests show very good agreement between

  20. In-situ transmission electron microscopy : on moving dislocations and mobile grain boundaries

    NARCIS (Netherlands)

    De Hosson, J. T. M.; Soer, W.

    This paper delineates the possibilities of utilizing in situ transmission electron microscopy to unravel dislocation-g rain boundary interactions. In situ nanoindentation experiments have been conducted in TEM on ultrafine-grained Al and Al-Mg films with varying Mg contents. The observed propagation

  1. Anisotropic Shape Changes of Silica Nanoparticles Induced in Liquid with Scanning Transmission Electron Microscopy

    NARCIS (Netherlands)

    Zecevic, J.; Hermannsdorfer, Justus; Schuh, Tobias; de Jong, Krijn P.; de Jonge, Niels

    2017-01-01

    Liquid-phase transmission electron microscopy (TEM) is used for in-situ imaging of nanoscale processes taking place in liquid, such as the evolution of nanoparticles during synthesis or structural changes of nanomaterials in liquid environment. Here, it is shown that the focused electron beam of

  2. Morphostructural Damage in Food-Spoiling Bacteria due to the Lemon Grass Oil and Its Vapour: SEM, TEM, and AFM Investigations

    Science.gov (United States)

    Tyagi, Amit Kumar; Malik, Anushree

    2012-01-01

    In this study, antimicrobial activity and morphostructural damages due to lemon grass oil (LGO) and its vapour (LGOV) against Escherichia coli strains were investigated. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of LGO were determined by broth-dilution method to be 0.288 mg/mL and 0.567 mg/mL, respectively. Furthermore, the zone of inhibition (45 mm) due to the vapour phase antimicrobial efficacy evaluated using disc volatilization assay was compared with that using disc diffusion assay (i.e., 13.5 mm for the same dose of oil). The morphological and ultrastructural alterations in LGO- and LGOV-treated E. coli cells were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic-force microscopy (AFM). In SEM observation, LGO-treated cells appeared to be aggregated and partially deformed, while LGOV-treated cells lost their turgidity, and the cytoplasmic material completely leaked from the cells. In TEM observation, extensive intracytoplasmic changes and various abnormalities were observed in LGOV-treated cells more than LGO-treated cells. Significant variations in the height and root mean square values of untreated, LGO-, and LGOV-treated E. coli cells were noticed by AFM. Present results indicate that LGO is highly effective against E. coli in vapour phase. PMID:23082083

  3. TEM10 homodyne detection as an optimal small-displacement and tilt-measurement scheme

    DEFF Research Database (Denmark)

    Delaubert, Vincent; Treps, Nikolas; Lassen, Mikael Østergaard

    2006-01-01

    We report an experimental demonstration of optimal measurements of small displacement and tilt of a Gaussian beam - two conjugate variables - involving a homodyne detection with a TEM10 local oscillator. We verify that the standard split detection is only 64% efficient. We also show a displacemen...... measurement beyond the quantum noise limit, using a squeezed vacuum TEM10 mode within the input beam....

  4. Molecular identification of TEM-116 beta-lactamase gene in isolates ...

    African Journals Online (AJOL)

    Purpose: Purpose: To determine TEM-116 beta-lactamase gene prevalence in drug-resistant Pseudomonas aeruginosa isolates from Pakistan. Methods: Sequence analysis of TEM beta-lactamase isolates and their antibiotic susceptibility patterns were carried out. Quantitative bacteriostatic concentrations for commonly ...

  5. Optical, mechanical and TEM assessment of titania-doped Bi2V1 ...

    Indian Academy of Sciences (India)

    pension and heavy ones are settled. The TEM samples have been prepared using Wick's procedure. A drop of liquid is placed on a carbon film supported over copper grid. After the film is dried, the grid is introduced to TEM. 3. Results and discussion. 3.1 Absorption studies. The optical properties of materials are always ...

  6. HUMAN CAPSULE EPITHELIAL-CELL DEGENERATION A LM, SEM AND TEM INVESTIGATION

    NARCIS (Netherlands)

    JONGEBLOED, WL; KALICHARAN, D; WORST, JGF

    1993-01-01

    The degeneration of the capsule epithelium of cataractous lenses has been studied with LM, SEM on TEM with emphases on TEM. The observed degeneration of the epithelial cells can be described as follows: The cell nucleus becomes picnotic and desintegrates as result of change of the chromatin.

  7. THE MORGAGNIAN AND BRUNESCENS CATARACT MORPHOLOGY STUDIES WITH SEM AND TEM

    NARCIS (Netherlands)

    JONGEBLOED, WL; KALICHARAN, D; LOS, LI; WORST, JGF

    1993-01-01

    The Morgagnian cataract lenses - pre-fixed with GA for SEM & TEM and post-fixed with tannic-acid-arginine-OsO4 for SEM and OsO4/K4Fe(CN)6 for TEM after staining with Ur-acetate/Pb-citrate - showed areas in the cortex with radial in stead of concentric running lensfibres, degeneration of lensfibres

  8. Investigation of diversity of plasmids carrying the blaTEM-52 gene

    DEFF Research Database (Denmark)

    Bielak, Eliza Maria; Bergenholtz, Rikke D.; Jørgensen, Mikael Skaanning

    2011-01-01

    (RFLP), replicon typing (by PCR or replicon sequencing), susceptibility testing, assessment of plasmid ability to self-transfer by conjugation and typing of the genetic environment of the blaTEM-52 gene. Detected IncI1 plasmids underwent further plasmid multilocus sequence typing. RESULTS: RFLP profiles...... demonstrated dissemination of blaTEM-52 in Denmark (imported meat from Germany), France, Belgium and the Netherlands from 2000 to 2006 by mainly two different plasmids, one encoding blaTEM-52b (IncX1A, 45 kb) and the other blaTEM-52c (IncI1, 80 kb). In addition, blaTEM-52b was also found to be located...... on various other plasmids belonging to IncA/C and IncL/M, while blaTEM-52c was found on IncN-like as well as on IncR plasmids. In the majority of cases (n = 21) the blaTEM-52 gene was located on a Tn3 transposon. Seven out of 10 blaTEM-52 plasmids tested in conjugation experiments were shown to be capable...

  9. The RhoGEF TEM4 Regulates Endothelial Cell Migration by Suppressing Actomyosin Contractility.

    Directory of Open Access Journals (Sweden)

    Natalia Mitin

    Full Text Available Persistent cellular migration requires efficient protrusion of the front of the cell, the leading edge where the actin cytoskeleton and cell-substrate adhesions undergo constant rearrangement. Rho family GTPases are essential regulators of the actin cytoskeleton and cell adhesion dynamics. Here, we examined the role of the RhoGEF TEM4, an activator of Rho family GTPases, in regulating cellular migration of endothelial cells. We found that TEM4 promotes the persistence of cellular migration by regulating the architecture of actin stress fibers and cell-substrate adhesions in protruding membranes. Furthermore, we determined that TEM4 regulates cellular migration by signaling to RhoC as suppression of RhoC expression recapitulated the loss-of-TEM4 phenotypes, and RhoC activation was impaired in TEM4-depleted cells. Finally, we showed that TEM4 and RhoC antagonize myosin II-dependent cellular contractility and the suppression of myosin II activity rescued the persistence of cellular migration of TEM4-depleted cells. Our data implicate TEM4 as an essential regulator of the actin cytoskeleton that ensures proper membrane protrusion at the leading edge of migrating cells and efficient cellular migration via suppression of actomyosin contractility.

  10. Electrochemical force microscopy

    Science.gov (United States)

    Kalinin, Sergei V.; Jesse, Stephen; Collins, Liam F.; Rodriguez, Brian J.

    2017-01-10

    A system and method for electrochemical force microscopy are provided. The system and method are based on a multidimensional detection scheme that is sensitive to forces experienced by a biased electrode in a solution. The multidimensional approach allows separation of fast processes, such as double layer charging, and charge relaxation, and slow processes, such as diffusion and faradaic reactions, as well as capturing the bias dependence of the response. The time-resolved and bias measurements can also allow probing both linear (small bias range) and non-linear (large bias range) electrochemical regimes and potentially the de-convolution of charge dynamics and diffusion processes from steric effects and electrochemical reactivity.

  11. Reinventing Pocket Microscopy

    CERN Document Server

    Kamal, T; Lee, W M

    2015-01-01

    The key to the success of pocket microscopes stems from the convenience for anyone to magnify the fine details (tens of micrometres) of any object on-thespot. The capability with a portable microscope lets us surpass our limited vision and is commonly used in many areas of science, industry, education. The growth of imaging and computing power in smartphones is creating the possibility of converting your smartphone into a high power pocket microscope. In this article, we briefly describe the history of pocket microscopy and elucidate how mobile technologies are set to become the next platform for pocket microscopes

  12. Chronological changes in the ultrastructure of titanium-bone interfaces: analysis by light microscopy, transmission electron microscopy, and micro-computed tomography.

    Science.gov (United States)

    Morinaga, Kenzo; Kido, Hirofumi; Sato, Atsuko; Watazu, Akira; Matsuura, Masaro

    2009-03-01

    The objectives of this study were to chronologically examine the titanium-bone interfaces and to clarify the process of osseointegration using light microscopy, transmission electron microscopy (TEM), and micro-computed tomography (CT). Experimental implants (Ti-coating plastic implants) were placed into tibiae of 8-week-old rats. Animals were sacrificed at 1 to 28 days after implant placement and prepared tissue specimens for a light microscope, a TEM, and micro-CT. New bone formation began 5 days after implant placement, and osseointegration was obtained by 14 days after implant placement. Osseointegration was well developed by 28 days after implant placement. TEM and quantitative computer tomography (QCT) results indicated that bone formation in osseointegration of titanium implants did not occur from the surfaces of the implant or preexisting bone, but it was likely that bone formation progressed at a site a small distance away from the surface. The bone formation took place in a scattered manner. Small bone fragments adhered to each other and transformed into reticular-shaped bone, and finally these bones became lamellar bone. Comparative analysis of the titanium-bone interfaces using light microscopy, TEM, and QCT by micro-CT revealed the precise process of osseointegration.

  13. Correlative Stochastic Optical Reconstruction Microscopy and Electron Microscopy

    Science.gov (United States)

    Kim, Doory; Deerinck, Thomas J.; Sigal, Yaron M.; Babcock, Hazen P.; Ellisman, Mark H.; Zhuang, Xiaowei

    2015-01-01

    Correlative fluorescence light microscopy and electron microscopy allows the imaging of spatial distributions of specific biomolecules in the context of cellular ultrastructure. Recent development of super-resolution fluorescence microscopy allows the location of molecules to be determined with nanometer-scale spatial resolution. However, correlative super-resolution fluorescence microscopy and electron microscopy (EM) still remains challenging because the optimal specimen preparation and imaging conditions for super-resolution fluorescence microscopy and EM are often not compatible. Here, we have developed several experiment protocols for correlative stochastic optical reconstruction microscopy (STORM) and EM methods, both for un-embedded samples by applying EM-specific sample preparations after STORM imaging and for embedded and sectioned samples by optimizing the fluorescence under EM fixation, staining and embedding conditions. We demonstrated these methods using a variety of cellular targets. PMID:25874453

  14. Multimodal hyperspectral optical microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Novikova, Irina V.; Smallwood, Chuck R.; Gong, Yu; Hu, Dehong; Hendricks, Leif; Evans, James E.; Bhattarai, Ashish; Hess, Wayne P.; El-Khoury, Patrick Z.

    2017-09-01

    We describe a unique and convenient approach to multimodal hyperspectral optical microscopy, herein achieved by coupling a portable and transferable hyperspectral imager to various optical microscopes. The experimental and data analysis schemes involved in recording spectrally and spatially resolved fluorescence, dark field, and optical absorption micrographs are illustrated through prototypical measurements targeting selected model systems. Namely, hyperspectral fluorescence micrographs of isolated fluorescent beads are employed to ensure spectral calibration of our detector and to gauge the attainable spatial resolution of our measurements; the recorded images are diffraction-limited. Moreover, spatially over-sampled absorption spectroscopy of a single lipid (18:1 Liss Rhod PE) layer reveals that optical densities on the order of 10-3 may be resolved by spatially averaging the recorded optical signatures. We also briefly illustrate two applications of our setup in the general areas of plasmonics and cell biology. Most notably, we deploy hyperspectral optical absorption microscopy to identify and image algal pigments within a single live Tisochrysis lutea cell. Overall, this work paves the way for multimodal multidimensional spectral imaging measurements spanning the realms of several scientific disciples.

  15. Magnetic force microscopy

    Science.gov (United States)

    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

    2014-01-01

    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

  16. Digital holographic microscopy

    Science.gov (United States)

    Barkley, Solomon; Dimiduk, Thomas; Manoharan, Vinothan

    Digital holographic microscopy is a 3D optical imaging technique with high temporal ( ms) and spatial ( 10 nm) precision. However, its adoption as a characterization technique has been limited due to the inherent difficulty of recovering 3D data from the holograms. Successful analysis has traditionally required substantial knowledge about the sample being imaged (for example, the approximate positions of particles in the field of view), as well as expertise in scattering theory. To overcome the obstacles to widespread adoption of holographic microscopy, we developed HoloPy - an open source python package for analysis of holograms and scattering data. HoloPy uses Bayesian statistical methods to determine the geometry and properties of discrete scatterers from raw holograms. We demonstrate the use of HoloPy to measure the dynamics of colloidal particles at interfaces, to ascertain the structures of self-assembled colloidal particles, and to track freely swimming bacteria. The HoloPy codebase is thoroughly tested and well-documented to facilitate use by the broader experimental community. This research is supported by NSF Grant DMR-1306410 and NSERC.

  17. Clean electromigrated nanogaps imaged by transmission electron microscopy.

    Science.gov (United States)

    Strachan, Douglas R; Smith, Deirdre E; Fischbein, Michael D; Johnston, Danvers E; Guiton, Beth S; Drndić, Marija; Bonnell, Dawn A; Johnson, Alan T

    2006-03-01

    Electromigrated nanogaps have shown great promise for use in molecular scale electronics. We have fabricated nanogaps on free-standing transparent SiN(x) membranes which permit the use of transmission electron microscopy (TEM) to image the gaps. The electrodes are formed by extending a recently developed controlled electromigration procedure and yield a nanogap with approximately 5 nm separation clear of any apparent debris. The gaps are stable, on the order of hours as measured by TEM, but over time (months) relax to about 20 nm separation determined by the surface energy of the Au electrodes. A major benefit of electromigrated nanogaps on SiN(x) membranes is that the junction pinches in away from residual metal left from the Au deposition which could act as a parasitic conductance path. This work has implications to the design of clean metallic electrodes for use in nanoscale devices where the precise geometry of the electrode is important.

  18. Localization of Minodronate in Mouse Femora Through Isotope Microscopy.

    Science.gov (United States)

    Hongo, Hiromi; Sasaki, Muneteru; Kobayashi, Sachio; Hasegawa, Tomoka; Yamamoto, Tomomaya; Tsuboi, Kanako; Tsuchiya, Erika; Nagai, Tomoya; Khadiza, Naznin; Abe, Miki; Kudo, Ai; Oda, Kimimitsu; Henrique Luiz de Freitas, Paulo; Li, Minqi; Yurimoto, Hisayoshi; Amizuka, Norio

    2016-10-01

    Minodronate is highlighted for its marked and sustained effects on osteoporotic bones. To determine the duration of minodronate's effects, we have assessed the localization of the drug in mouse bones through isotope microscopy, after labeling it with a stable nitrogen isotope ([(15)N]-minodronate). In addition, minodronate-treated bones were assessed by histochemistry and transmission electron microscopy (TEM). Eight-week-old male ICR mice received [(15)N]-minodronate (1 mg/kg) intravenously and were sacrificed after 3 hr, 24 hr, 1 week, and 1 month. Isotope microscopy showed that [(15)N]-minodronate was present mainly beneath osteoblasts rather than nearby osteoclasts. At 3 hr after minodronate administration, histochemistry and TEM showed osteoclasts with well-developed ruffled borders. However, osteoclasts were roughly attached to the bone surfaces and did not feature ruffled borders at 24 hr after minodronate administration. The numbers of tartrate-resistant acid phosphatase-positive osteoclasts and alkaline phosphatase-reactive osteoblastic area were not reduced suddenly, and apoptotic osteoclasts appeared in 1 week and 1 month after the injections. Von Kossa staining demonstrated that osteoclasts treated with minodronate did not incorporate mineralized bone matrix. Taken together, minodronate accumulates in bone underneath osteoblasts rather than under bone-resorbing osteoclasts; therefore, it is likely that the minodronate-coated bone matrix is resistant to osteoclastic resorption, which results in a long-lasting and bone-preserving effect. © 2016 The Histochemical Society.

  19. Observation of Bacteriophage Ultrastructure by Cryo-electron Microscopy.

    Science.gov (United States)

    Cuervo, Ana; Carrascosa, José L

    2018-01-01

    Transmission Electron Microscopy (TEM) is an ideal method to observe and determine the structure of bacteriophages. From early studies by negative staining to the present atomic structure models derived from cryo-TEM, bacteriophage detection, classification, and structure determination has been mostly done by electron microscopy. Although embedding in metal salts has been a routine method for virus observation for many years, preservation of bacteriophages in a thin layer of fast frozen buffer has proven to be a most convenient preparation method for obtaining images using cryo-electron microscopy (cryo-EM). In this technique, frozen samples are observed at liquid nitrogen temperature and the images are acquired using different recording media. The incorporation of direct electron detectors has been a fundamental step to achieve atomic resolution images of a number of viruses. These projection images can be numerically combined using different approaches to render a three-dimensional model of the virus. For those viral components exhibiting any symmetry, averaging procedures help to render near-atomic resolution structures.

  20. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials.

    Science.gov (United States)

    Agudo Jácome, L; Eggeler, G; Dlouhý, A

    2012-11-01

    Stereo transmission electron microscopy (TEM) provides a 3D impression of the microstructure in a thin TEM foil. It allows to perform depth and TEM foil thickness measurements and to decide whether a microstructural feature lies inside of a thin foil or on its surface. It allows appreciating the true three-dimensional nature of dislocation configurations. In the present study we first review some basic elements of classical stereo TEM. We then show how the method can be extended by working in the scanning transmission electron microscope (STEM) mode of a modern analytical 200 kV TEM equipped with a field emission gun (FEG TEM) and a high angle annular dark field (HAADF) detector. We combine two micrographs of a stereo pair into one anaglyph. When viewed with special colored glasses the anaglyph provides a direct and realistic 3D impression of the microstructure. Three examples are provided which demonstrate the potential of this extended stereo TEM technique: a single crystal Ni-base superalloy, a 9% Chromium tempered martensite ferritic steel and a NiTi shape memory alloy. We consider the effect of camera length, show how foil thicknesses can be measured, and discuss the depth of focus and surface effects. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Advanced microscopy of microbial cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Regenberg, Birgitte; Sternberg, Claus

    2011-01-01

    Growing awareness of heterogeneity in cells of microbial populations has emphasized the importance of advanced microscopy for visualization and understanding of the molecular mechanisms underlying cell-to-cell variation. In this review, we highlight some of the recent advances in confocal...... microscopy, super-resolution optical microscopy (STED, SIM, PALM) as well as atomic force microscopy and Raman spectroscopy. Using examples of bistability in microbial populations as well as biofilm development and differentiation in bacterial and yeast consortia, we demonstrate the importance of microscopy...

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

    Science.gov (United States)

    Tomitori, Masahiko; Sasahara, Akira

    2014-11-01

    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

  3. Single atom microscopy.

    Science.gov (United States)

    Zhou, Wu; Oxley, Mark P; Lupini, Andrew R; Krivanek, Ondrej L; Pennycook, Stephen J; Idrobo, Juan-Carlos

    2012-12-01

    We show that aberration-corrected scanning transmission electron microscopy operating at low accelerating voltages is able to analyze, simultaneously and with single atom resolution and sensitivity, the local atomic configuration, chemical identities, and optical response at point defect sites in monolayer graphene. Sequential fast-scan annular dark-field (ADF) imaging provides direct visualization of point defect diffusion within the graphene lattice, with all atoms clearly resolved and identified via quantitative image analysis. Summing multiple ADF frames of stationary defects produce images with minimized statistical noise and reduced distortions of atomic positions. Electron energy-loss spectrum imaging of single atoms allows the delocalization of inelastic scattering to be quantified, and full quantum mechanical calculations are able to describe the delocalization effect with good accuracy. These capabilities open new opportunities to probe the defect structure, defect dynamics, and local optical properties in 2D materials with single atom sensitivity.

  4. High-contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy.

    Science.gov (United States)

    Tapia, Juan Carlos; Kasthuri, Narayanan; Hayworth, Kenneth J; Schalek, Richard; Lichtman, Jeff W; Smith, Stephen J; Buchanan, JoAnn

    2012-01-12

    Conventional heavy metal poststaining methods on thin sections lend contrast but often cause contamination. To avoid this problem, we tested several en bloc staining techniques to contrast tissue in serial sections mounted on solid substrates for examination by field emission scanning electron microscopy (FESEM). Because FESEM section imaging requires that specimens have higher contrast and greater electrical conductivity than transmission electron microscopy (TEM) samples, our technique uses osmium impregnation (OTO) to make the samples conductive while heavily staining membranes for segmentation studies. Combining this step with other classic heavy metal en bloc stains, including uranyl acetate (UA), lead aspartate, copper sulfate and lead citrate, produced clean, highly contrasted TEM and scanning electron microscopy (SEM) samples of insect, fish and mammalian nervous systems. This protocol takes 7-15 d to prepare resin-embedded tissue, cut sections and produce serial section images.

  5. Growth of Ag-seeded III-V Nanowires and TEM Characterization

    DEFF Research Database (Denmark)

    Lindberg, Anna Helmi Caroline

    appropriate, the density and the vertical yield were obtained. The crystal structures for the grown nanowires have been investigated with TEM.We have also performed additional growths to further understand exactly how the nanowire growth proceeds as well as to understand the limitations of using Ag as a seed...... particle. The last chapter presents our results from combining TEM and Raman spectroscopy to evaluate the possibility to use Raman spectroscopy to nd stacking faults and crystal defects in GaAs and InAs wurtzite nanowires. We performed TEM on both InAs nanowires and GaAs nanowires to deduce the stacking...

  6. Progress in the Correlative Atomic Force Microscopy and Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Lulu Zhou

    2017-04-01

    Full Text Available Atomic force microscopy (AFM has evolved from the originally morphological imaging technique to a powerful and multifunctional technique for manipulating and detecting the interactions between molecules at nanometer resolution. However, AFM cannot provide the precise information of synchronized molecular groups and has many shortcomings in the aspects of determining the mechanism of the interactions and the elaborate structure due to the limitations of the technology, itself, such as non-specificity and low imaging speed. To overcome the technical limitations, it is necessary to combine AFM with other complementary techniques, such as fluorescence microscopy. The combination of several complementary techniques in one instrument has increasingly become a vital approach to investigate the details of the interactions among molecules and molecular dynamics. In this review, we reported the principles of AFM and optical microscopy, such as confocal microscopy and single-molecule localization microscopy, and focused on the development and use of correlative AFM and optical microscopy.

  7. Progress in the Correlative Atomic Force Microscopy and Optical Microscopy.

    Science.gov (United States)

    Zhou, Lulu; Cai, Mingjun; Tong, Ti; Wang, Hongda

    2017-04-24

    Atomic force microscopy (AFM) has evolved from the originally morphological imaging technique to a powerful and multifunctional technique for manipulating and detecting the interactions between molecules at nanometer resolution. However, AFM cannot provide the precise information of synchronized molecular groups and has many shortcomings in the aspects of determining the mechanism of the interactions and the elaborate structure due to the limitations of the technology, itself, such as non-specificity and low imaging speed. To overcome the technical limitations, it is necessary to combine AFM with other complementary techniques, such as fluorescence microscopy. The combination of several complementary techniques in one instrument has increasingly become a vital approach to investigate the details of the interactions among molecules and molecular dynamics. In this review, we reported the principles of AFM and optical microscopy, such as confocal microscopy and single-molecule localization microscopy, and focused on the development and use of correlative AFM and optical microscopy.

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

    Science.gov (United States)

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

    2010-01-01

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

  9. Thermal and shock metamorphism of the Tenham chondrite: A TEM examination

    Science.gov (United States)

    Langenhorst, Falko; Joreau, Pascal; Doukhan, Jean Claude

    1995-05-01

    During the early episode Of the solar system, the L6 chondrite Tenham has been affected by intense thermal metamorphism. Microanalytical data reveal homogeneous compositions Of Olivine (F O 75Fa 25), enstatite (En 79Fs 19W O 2), and diopside (En 47Fs 8W O 45). Using these data, empirical pyroxene thermometers yield temperature estimates for this thermal metamorphism, ranging from 810 to 870°C. Due to the presence of thin shock veins, which contain the high-pressure phases majorite and ringwoodite, the L6 chondrite Tenham is an instructive example for strong shock metamorphism. In contrast to previous transmission electron microscopy (TEM) studies, which concentrated on these shock veins, we also systematically characterized the shock signature of the silicates occurring in the bulk Of Tenham. Plagioclase is either pervaded by thin (200 nm), amorphous lamellae, so-called planar deformation features ("PDFs"), or it is transformed to maskelynite, a diaplectic glass Of feldspar composition. In olivine, shock deformation has caused the formation of irregular and planar fractures and the activation of numerous (2 × 10 14 m -2) c dislocations in the glide planes (100) and {110}; energetically favorable but less mobile a dislocations are totally absent. Fracturing in olivine is interpreted as the cause of dislocation formation. A low dislocation density (shock origin is most reasonable in this case because of the presence of strong shock damage in the other silicates. Diopside displays the greatest diversity of shock defects: mechanical twins parallel to (100) and (001), numerous dislocations, and PDFs. The predominant glide system of dislocations is (100)[001], but the {110}[001] glide system is also present to a lesser extent. To our knowledge, we report here on the first evidence of thin (≤50 nm), amorphous lamellae in naturally shocked diopside. These PDFs are oriented parallel to {221} and {221}. Fine-grained (ringwoodite, were observed in a thin shock vein

  10. Structure of the extended-spectrum β-lactamase TEM-72 inhibited by citrate.

    Science.gov (United States)

    Docquier, Jean Denis; Benvenuti, Manuela; Calderone, Vito; Rossolini, Gian Maria; Mangani, Stefano

    2011-03-01

    TEM-72, a class A β-lactamase identified in isolates of Enterobacteriaceae, is a quadruple mutant of TEM-1 (Q39K, M182T, G238S and E240K) and shows extended-spectrum β-lactamase (ESBL) properties arising from the G238S and E240K substitutions. Although many structures of TEM variants have been published, they do not include an enzyme with the simultaneous presence of both of the ESBL-conferring G238S and E240K substitutions. Furthermore, the structure shows the presence of a citrate anion bound to the TEM-72 active site, where it interacts with all of the conserved residues of class A β-lactamases. The present structure supports the use of polycarboxylates as a scaffold for the design of broad-spectrum inhibitors of serine β-lactamases.

  11. Fast FIB-milled Electron-transparent Microchips for in situ TEM Investigations

    DEFF Research Database (Denmark)

    Lei, Anders; Petersen, Dirch Hjorth; Kallesøe, Christian

    In this work we present a fast approach to 50 nm resolution structures defined in a generic TEM-chip template in few minutes. While creating complex electrical and NEMS circuits for a specific insitu TEM experiment can be a cumbersome process, microchips with 100 nm thin flakes of single...... crystalline silicon and silicon nitride membrane templates suspended from the edge, can be patterned in less than 15 minutes using focused ion beam milling. This approach allows a FIB-SEM user to create free-form NEMS structures for nanoresonators, actuators, heaters, resistors or other structures for insitu...... TEM devices or materials research using the same template. We demonstrate insitu environmental TEM analysis of Au film migration on silicon during resistive heating of a microbridge, and show how the conductance of focused ion beam milled single crystalline silicon nanowires can be adjusted insitu...

  12. First detection of bla TEM, SHV and CTX-M among Gram negative ...

    African Journals Online (AJOL)

    First detection of bla TEM, SHV and CTX-M among Gram negative bacilli exhibiting extended spectrum β- lactamase phenotype isolated at University Hospital Center, Yalgado Ouedraogo, Ouagadougou, Burkina Faso.

  13. Structure and dynamics of poly(oxyethylene) cholesteryl ether wormlike micelles: rheometry, SAXS, and cryo-TEM studies.

    Science.gov (United States)

    Shrestha, Rekha Goswami; Abezgauz, Ludmila; Danino, Dganit; Sakai, Kenichi; Sakai, Hideki; Abe, Masahiko

    2011-11-01

    In this article, we provide direct evidence for 1-D micellar growth and the formation of a network structure in an aqueous system of poly(oxyethylene) cholesteryl ether (ChEO(20)) and lauryl diethanolamide (L-02) by rheometry, small-angle X-ray scattering (SAXS), and cryo-transmission electron microscopy (cryo-TEM). The ChEO(20) self-assembles into spheroid micelles above the critical micelle concentration and undergoes a 1-D microstructural transition upon the incorporation of L-02, which because of its lipophilic nature tends to be solubilized into the micellar palisade layer and reduces the micellar curvature. The elongated micelles entangle with each other, forming network structures of wormlike micelles, and the system shows viscoelastic properties, which could be described by the Maxwell model. A peak observed in the zero-shear viscosity (η(0)) versus L-02 concentration curve shifted toward higher L-02 concentrations and the value of maximum viscosity (η(0 max)) increased with the increasing ChEO(20) mixing fraction with water. We observed that η(0 max) increased by 2 to 4 orders of magnitude as a function of the ChEO(20) concentration. The Maxwell relaxation time (τ(R)) shows a maximum value at a concentration corresponding to η(0 max) (i.e., τ(R) increases with L-02 concentration and then decreases after attaining a maximum value, whereas the plateau modulus (G(0)) shows monotonous growth). These observations demonstrate microstructural transitions in two different modes: L-02 first induces 1-D micellar growth and as a result the viscosity increases, and finally after the system attains its maximum viscosity, L-02 causes branching in the network structures. The microstructure transitions are confirmed by SAXS and cryo-TEM techniques.

  14. Coarsening of Pd nanoparticles in an oxidizing atmosphere studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren

    2016-01-01

    air at 650 °C. Time-resolved TEM image series reveal that the Pd nanoparticles were immobile and that a few percent of the nanoparticles grew or shrank, indicating a coarsening process mediated by the Ostwald ripening mechanism. The TEM image contrast suggests that the largest nanoparticles tended...... for the Ostwald ripening process indicates that the observed change in the particle size distribution can be accounted for by wetting of the Al2O3 support by the larger Pd nanoparticles....

  15. Use of the TEM Cell for Compliance Testing of Emissions and Immunity, an IEC Perspective

    DEFF Research Database (Denmark)

    Bentz, Sigurd

    1996-01-01

    The current work of the IEC on preparing a standard for the use of TEM cells for compliance testing of emissions and immunity is reviewed. The requirements of TEM cells are related to the established procedures: “open area test site” and “shielded enclosure with area of uniform field”, respective....... The problems of incorporating new technology into standardization as well as the existence of parallel standardized test procedures are discussed...

  16. Binding of TEM-1 beta-lactamase to beta-lactam antibiotics by frontal affinity chromatography.

    Science.gov (United States)

    Chen, Xiu; Li, Yuhua; Zhang, Yan; Yang, Jianting; Bian, Liujiao

    2017-04-15

    TEM-1 beta-lactamases can accurately catalyze the hydrolysis of the beta-lactam rings in beta-lactam antibiotics, which make beta-lactam antibiotics lose its activity, and the prerequisite for the hydrolysis procedure in the binding interaction of TEM-1 beta-lactamases with beta-lactam antibiotics is the beta-lactam rings in beta-lactam antibiotics. Therefore, the binding of TEM-1 beta-lactamase to three beta-lactam antibiotics including penicillin G, cefalexin as well as cefoxitin was explored here by frontal affinity chromatography in combination with fluorescence spectra, adsorption and thermodynamic data in the temperature range of 278-288K under simulated physiological conditions. The results showed that all the binding of TEM-1 beta-lactamase to the three antibiotics were spontaneously exothermic processes with the binding constants of 8.718×103, 6.624×103 and 2.244×103 (mol/L), respectively at 288K. All the TEM-1 beta-lactamases were immobilized on the surface of the stationary phase in the mode of monolayer and there existed only one type of binding sites on them. Each TEM-1 beta-lactamase bound with only one beta-lactam antibiotic and hydrogen bond interaction and Van der Waals force were the main forces between them. This work provided an insight into the binding interactions between TEM-1 beta-lactamases and beta-lactam antibiotics, which may be beneficial for the designing and developing of new substrates resistant to TEM-1 beta-lactamases. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. NDE Acoustic Microscopy Research Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to develop advanced, more effective high-resolution micro-NDE materials characterization methods using scanning acoustic microscopy. The laboratory's...

  18. Magnetic Resonance Force Microscopy System

    Data.gov (United States)

    Federal Laboratory Consortium — The Magnetic Resonance Force Microscopy (MRFM) system, developed by ARL, is the world's most sensitive nuclear magnetic resonance (NMR) spectroscopic analysis tool,...

  19. Comparison between measured and predicted turbulence frequency spectra in ITG and TEM regimes

    Science.gov (United States)

    Citrin, J.; Arnichand, H.; Bernardo, J.; Bourdelle, C.; Garbet, X.; Jenko, F.; Hacquin, S.; Pueschel, M. J.; Sabot, R.

    2017-06-01

    The observation of distinct peaks in tokamak core reflectometry measurements—named quasi-coherent-modes (QCMs)—are identified as a signature of trapped-electron-mode (TEM) turbulence (Arnichand et al 2016 Plasma Phys. Control. Fusion 58 014037). This phenomenon is investigated with detailed linear and nonlinear gyrokinetic simulations using the Gene code. A Tore-Supra density scan is studied, which traverses through a linear (LOC) to saturated (SOC) ohmic confinement transition. The LOC and SOC phases are both simulated separately. In the LOC phase, where QCMs are observed, TEMs are robustly predicted unstable in linear studies. In the later SOC phase, where QCMs are no longer observed, ion-temperature-gradient (ITG) modes are identified. In nonlinear simulations, in the ITG (SOC) phase, a broadband spectrum is seen. In the TEM (LOC) phase, a clear emergence of a peak at the TEM frequencies is seen. This is due to reduced nonlinear frequency broadening of the underlying linear modes in the TEM regime compared with the ITG regime. A synthetic diagnostic of the nonlinearly simulated frequency spectra reproduces the features observed in the reflectometry measurements. These results support the identification of core QCMs as an experimental marker for TEM turbulence.

  20. TEM observations of Al{sub 72}Ni{sub 12}Co{sub 16} decagonal quasicrystal subjected to high-temperature indentation

    Energy Technology Data Exchange (ETDEWEB)

    Saito, K. [Department of Materials Science and Engineering, Akita University, Akita 010-8502 (Japan)]. E-mail: ksaito@ipc.akita-u.ac.jp; Arakaki, Y. [Department of Materials Science and Engineering, Akita University, Akita 010-8502 (Japan); Sugawara, S. [Department of Materials Science and Engineering, Akita University, Akita 010-8502 (Japan); Shindo, R. [Akita Prefecture Industrial Technology Center, Akita 010-1623 (Japan); Guo, J.Q. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsai, A.P. [National Institute for Materials Science, Tsukuba 305-0047 (Japan)

    2005-08-25

    The effect of high-temperature indentation testing on the microstructural change of a single-grained Al{sub 72}Ni{sub 12}Co{sub 16} decagonal quasicrystal (d-QC) has been investigated by transmission electron diffraction and microscopy (TEM) technique. A definite surface normal to the 10-fold axis of the d-QC was subjected to Vickers indentation test at an elevated temperature of 800 deg. C with a load of 1 kgf. The TEM investigation of this sample has evidently shown that there are specific types of defects densely distributed in the indented-region, such as grain-boundaries, dislocations and phason-related defects. Furthermore, high-resolution electron microscopy observations have revealed the widespread distribution of nanocrystalline domains in the indented-region, where groups of decagonal atom clusters have a periodic arrangement to form a rhombic lattice. On the basis of these observations, possible deformation mechanisms of the d-QC during high-temperature indentation will be discussed.

  1. (CryoTransmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

    Directory of Open Access Journals (Sweden)

    Annette Meister

    2017-10-01

    Full Text Available Lipid membranes can incorporate amphiphilic or polyphilic molecules leading to specific functionalities and to adaptable properties of the lipid bilayer host. The insertion of guest molecules into membranes frequently induces changes in the shape of the lipid matrix that can be visualized by transmission electron microscopy (TEM techniques. Here, we review the use of stained and vitrified specimens in (cryoTEM to characterize the morphology of amphiphilic and polyphilic molecules upon insertion into phospholipid model membranes. Special emphasis is placed on the impact of novel synthetic amphiphilic and polyphilic bolalipids and polymers on membrane integrity and shape stability.

  2. Advanced Transmission Electron Microscopy Applications in Nano-Materials and Nano-Technology Developments

    Institute of Scientific and Technical Information of China (English)

    KAI; J.J.

    2001-01-01

    Nano-technology development is nowadays a very hot topics in many research fields. Nano-materials are the foundations for developing this new technology. In order to fully understand the basic material science problems behind this topics, transmission electron microscopy (TEM) becomes the must and one of the most important technique to analyze the nano-size structure and composition using the most advanced high resolution TEM technique with nano-beam EDS and energy filter EELS to study the fine structures, crystallography, chemical composition, and optical properties of many different nano-materials in different industries applications.  ……

  3. Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research.

    Science.gov (United States)

    Hodnik, Nejc; Dehm, Gerhard; Mayrhofer, Karl J J

    2016-09-20

    The foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like electrolyzers or fuel cells. Transmission electron microscopy (TEM) and scanning transmission electron microscope (STEM) are to a great extent nondestructive characterization tools that provide structural, morphological, and compositional information with nanoscale or even atomic resolution. Due to recent marked advancement in electron microscopy equipment such as aberration corrections and monochromators, such insightful information is now accessible in many institutions around the world and provides huge benefit to everyone using electron microscopy characterization in general. Classical ex situ TEM characterization of random catalyst locations however suffers from two limitations regarding catalysis. First, the necessary low operation pressures in the range of 10(-6) to 10(-9) mbar for TEM are not in line with typical reaction conditions, especially considering electrocatalytic solid-liquid interfaces, so that the active state cannot be assessed. Second, and somewhat related, is the lack of time resolution for the

  4. Extensive FE-SEM/EDS, HR-TEM/EDS and ToF-SIMS studies of micron- to nano-particles in anthracite fly ash.

    Science.gov (United States)

    Ribeiro, Joana; DaBoit, Kátia; Flores, Deolinda; Kronbauer, Marcio A; Silva, Luis F O

    2013-05-01

    The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100 nm size range by worldwide coal power plants represents serious environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples. Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1 nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Extensive FE-SEM/EDS, HR-TEM/EDS and ToF-SIMS studies of micron- to nano-particles in anthracite fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Joana [Centro de Geologia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); DaBoit, Kátia [Institute of Environmental Research and Human Development, IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Flores, Deolinda [Centro de Geologia, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Kronbauer, Marcio A. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Silva, Luis F.O., E-mail: felipeqma@hotmail.com [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Environmental Science and Nanotechnology Department, Catarinense Institute of Environmental Research and Human Development, IPADHC, Capivari de Baixo, Santa Catarina (Brazil)

    2013-05-01

    The generation of anthropogenic carbonaceous matter and mixed crystalline/amorphous mineral ultrafine/nano-particles in the 1 to 100 nm size range by worldwide coal power plants represents serious environmental problems due to their potential hazards. Coal fly ash (CFA) that resulted from anthracite combustion in a Portuguese thermal power plant was studied in this work. The physico-chemical characterization of ultrafine/nano-particles present in the CFA samples and their interaction with environment are the aim of this study. The methodologies applied for this work were field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy with energy dispersive X-ray spectroscopy (HR-TEM/EDS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Some hazardous volatile elements, C, N, S and Hg contents were also determined in the studied samples. Generally, the CFA samples comprise carbonaceous, glassy and metallic solid spheres with some containing mixed amorphous/crystalline phases. The EDS analysis coupled with the FE-SEM and HR-TEM observations of the fly ash particles with 100 to 0.1 nm demonstrates that these materials contain a small but significant proportion of encapsulated HVEs. In addition, the presence of abundant multi-walled carbon nanotubes (MWCNTs) and amorphous carbon particles, both containing hazardous volatile elements (HVEs), was also evidenced by the FE-SEM/EDS and HR-TEM/EDS analysis. A wide range of organic and inorganic compounds was determined by chemical maps obtained in ToF-SIMS analysis. - Highlights: ► We examine changes in the level of ultrafine and nanoparticles of coal mining. ► Increasing geochemical information will increase human health information in this area. ► Electron bean and Tof-SIMS increase area information.

  6. Field emission scanning electron microscopy and transmission electron microscopy studies of the chorion, plasma membrane and syncytial layers of the gastrula-stage embryo of the zebrafish Brachydanio rerio : a consideration of the structural and functional relationships with respect to cryoprotectant penetration

    NARCIS (Netherlands)

    Rawson, DM; Zhang, T; Kalicharan, D; Jongebloed, WL

    The structure of the chorion and plasma membranes of gastrula-stage zebrafish Brachydanio rerio embryos were studied using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). These studies confirm the outer chorion membrane complex to be 1.5-2.5 mu m in

  7. Advanced computing in electron microscopy

    CERN Document Server

    Kirkland, Earl J

    2010-01-01

    This book features numerical computation of electron microscopy images as well as multislice methods High resolution CTEM and STEM image interpretation are included in the text This newly updated second edition will bring the reader up to date on new developments in the field since the 1990's The only book that specifically addresses computer simulation methods in electron microscopy

  8. Electronic Blending in Virtual Microscopy

    Science.gov (United States)

    Maybury, Terrence S.; Farah, Camile S.

    2010-01-01

    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…

  9. Vibrational phase contrast CARS microscopy

    NARCIS (Netherlands)

    Jurna, M.

    2010-01-01

    This thesis describes a new technique that improves specificity, selectivity and sensitivity in coherent anti-Stokes Raman scattering (CARS) microscopy. CARS microscopy is a nonlinear optical technique that utilizes specific bonds of molecules, sometimes referred to as the `fingerprint' of a

  10. Spatial light interference microscopy (SLIM).

    Science.gov (United States)

    Wang, Zhuo; Millet, Larry; Mir, Mustafa; Ding, Huafeng; Unarunotai, Sakulsuk; Rogers, John; Gillette, Martha U; Popescu, Gabriel

    2011-01-17

    We present spatial light interference microscopy (SLIM) as a new optical microscopy technique, capable of measuring nanoscale structures and dynamics in live cells via interferometry. SLIM combines two classic ideas in light imaging: Zernike's phase contrast microscopy, which renders high contrast intensity images of transparent specimens, and Gabor's holography, where the phase information from the object is recorded. Thus, SLIM reveals the intrinsic contrast of cell structures and, in addition, renders quantitative optical path-length maps across the sample. The resulting topographic accuracy is comparable to that of atomic force microscopy, while the acquisition speed is 1,000 times higher. We illustrate the novel insight into cell dynamics via SLIM by experiments on primary cell cultures from the rat brain. SLIM is implemented as an add-on module to an existing phase contrast microscope, which may prove instrumental in impacting the light microscopy field at a large scale.

  11. Correlation of the same fields imaged in the TEM, confocal, LM, and microCT by image registration: from specimen preparation to displaying a final composite image.

    Science.gov (United States)

    Keene, Douglas R; Tufa, Sara F; Wong, Melissa H; Smith, Nicholas R; Sakai, Lynn Y; Horton, William A

    2014-01-01

    Correlated imaging is the process of imaging a specimen with two complementary modalities and then registering and overlaying the fields obtained in each modality to create a composite view. One of the images is made somewhat transparent, allowing detail in the underlying image to be visible and assisting in the registration of the two images. As an example, an image localizing a specific tissue component by fluorescence may be overlaid atop a TEM image of the same field. The resulting composite image would demonstrate specific ultrastructural features in the high-resolution TEM field, which are colorized in the overlay. Other examples include composites from MicroCT or soft X-ray images overlaid atop light microscopy or TEM images. Automated image registration may be facilitated by a variety of sophisticated computer programs utilized by high-throughput laboratories. This chapter is meant for the more occasional user wishing to align images manually. ImageJ is a public domain, image processing program developed at the National Institutes of Health and is available to anyone as a free download. ImageJ performs marvelously well for the purpose of image registration; therefore, step-by-step instructions are included here. Specimen handling, including fixation and choice of embedding media, is not straightforward for correlative imaging. A step-by-step description of the protocols which work in our laboratory is included for simultaneous localization in LM, EM and micro-CT, as well as maintaining GFP emission in tissue embedded for TEM. © 2014 Elsevier Inc. All rights reserved.

  12. Annular dark field transmission electron microscopy for protein structure determination

    Energy Technology Data Exchange (ETDEWEB)

    Koeck, Philip J.B., E-mail: Philip.Koeck@ki.se

    2016-02-15

    Recently annular dark field (ADF) transmission electron microscopy (TEM) has been advocated as a means of recording images of biological specimens with better signal to noise ratio (SNR) than regular bright field images. I investigate whether and how such images could be used to determine the three-dimensional structure of proteins given that an ADF aperture with a suitable pass-band can be manufactured and used in practice. I develop an approximate theory of ADF-TEM image formation for weak amplitude and phase objects and test this theory using computer simulations. I also test whether these simulated images can be used to calculate a three-dimensional model of the protein using standard software and discuss problems and possible ways to overcome these. - Highlights: • I present theory and simulations for imaging proteins using annular dark field transmission electron microscopy and investigate its suitability for 3D-reconstruction. • I show that the images are approximately proportional to the square of the projected electrostatic potential within a given passband ). • 3D-reconstructions show errors in the interior of the molecule. More accurate maps might be calculated by reconstruction algorithms that take into account non-linear image formation.

  13. Noncovalent Interaction Energies in Covalent Complexes: TEM-1 beta-Lactamase and beta-Lactams

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun; Minasov, George; Shoichet, Brian K. (NWU)

    2010-03-08

    The class A {beta}-lactamase TEM-1 is a key bacterial resistance enzyme against {beta}-lactam antibiotics, but little is known about the energetic bases for complementarity between TEM-1 and its inhibitors. Most inhibitors form a covalent adduct with the catalytic Ser70, making the measurement of equilibriumconstants, and hence interaction energies, technically difficult. This study evaluates noncovalent interactions withincovalent complexes by examining the differential stability of TEM-1 and its inhibitor adducts. The thermal denaturation of TEM-1 follows a two-state, reversible model with a melting temperature (T{sub m}) of 51.6 C and a van't Hoff enthalpy of unfolding ({Delta}H{sub VH}) of 146.2 kcal/mol at pH 7.0. The stability of the enzyme changes on forming an inhibitor adduct. As expected, some inhibitors stabilize TEM-1; transition-state analogues increase the T{sub m} by up to 3.7 C(1.7 kcal/mol). Surprisingly, all {beta}-lactam covalent acyl-enzyme complexes tested destabilize TEM-1 significantly relative to the apoenzyme. For instance, the clinically used inhibitor clavulanic acid and the {beta}-lactamase-resistant {beta}-lactams moxalactam and imipenem destabilize TEM-1 by over 2.6 C (1.2 kcal/mol) in their covalent adducts. Based on the structure of the TEM-1/imipenem complex (Maveyraud et al., J Am Chem Soc 1998;120:9748-52), destabilization by moxalactam and imipenem is thought to be caused by a steric clash between the side-chain of Asn132 and the 6(7)-{alpha} group of these {beta}-lactams. To test this hypothesis, the mutant enzyme N132A was made. In contrast with wild-type, the covalent complexes between N132A and both imipenem and moxalactam stabilize the enzyme, consistent with the hypothesis. To investigate the structural bases of this dramatic change instability, the structure of N132A/imipenem was determined by X-ray crystallography. In the complex with N132A, imipenemadopts a very different conformation from that observed in the wild

  14. Phase TEM for biological imaging utilizing a Boersch electrostatic phase plate: theory and practice.

    Science.gov (United States)

    Shiue, Jessie; Chang, Chia-Seng; Huang, Sen-Hui; Hsu, Chih-Hao; Tsai, Jin-Sheng; Chang, Wei-Hau; Wu, Yi-Min; Lin, Yen-Chen; Kuo, Pai-Chia; Huang, Yang-Shan; Hwu, Yeukuang; Kai, Ji-Jung; Tseng, Fan-Gang; Chen, Fu-Rong

    2009-06-01

    A Boersch electrostatic phase plate (BEPP) used in a transmission electron microscope (TEM) system can provide tuneable phase shifts and overcome the low contrast problem for biological imaging. Theoretically, a pure phase image with a high phase contrast can be obtained using a BEPP. However, a currently available TEM system utilizing a BEPP cannot achieve sufficiently high phase efficiency for biological imaging, owing to the practical conditions. The low phase efficiency is a result of the blocking of partial unscattered electrons by BEPP, and the contribution of absorption contrast. The fraction of blocked unscattered beam is related to BEPP dimensions and to divergence of the illumination system of the TEM. These practical issues are discussed in this paper. Phase images of biological samples (negatively stained ferritin) obtained by utilizing a BEPP are reported, and the phase contrast was found to be enhanced by a factor of approximately 1.5, based on the calculation using the Rose contrast criterion. The low gain in phase contrast is consistent with the expectation from the current TEM/BEPP system. A new generation of phase TEM utilizing BEPP and designed for biological imaging with a high phase efficiency is proposed.

  15. Structure and Output Characteristics of a TEM Array Fitted to a Fin Heat Exchanger

    Science.gov (United States)

    Zhang, Z.; Chen, L. N.; Chen, Z. J.; Xiao, G. Q.; Liu, Z. J.

    2015-06-01

    In the design of a thermoelectric generator, both the heat transfer area and the number of thermoelectric modules (TEMs) should be increased accordingly as the generator power increases; crucially, both aspects need to be coordinated. A kilowatt thermoelectric generator with a fin heat exchanger is proposed for use in a constant-speed diesel generator unit. Interior fins enhance convective heat transfer, whereas an exterior fin segment increases the heat transfer area. The heat transfer surface is double that of a plane heat exchanger, and the temperature field over the exterior fins is constrained to a one-dimensional distribution. Between adjoining exterior fins, there is a cooling water channel with trapezoid cross-section, enabling compact TEMs and cooling them. Hence, more TEMs are built as a series-parallel array of TEMs with lower resistance and more stable output current. Under nonuniform conditions, to prevent circulation and energy loss, bypass diodes and antidiodes are added. Experiments and numerical calculations show that, with matching and optimization of the heat exchanger and TEM array, a stable maximum output power is obtainable from the interior of the thermoelectric generator system, which can be connected to an external maximum power point tracking system.

  16. Chemical Reactions of Molecules Promoted and Simultaneously Imaged by the Electron Beam in Transmission Electron Microscopy.

    Science.gov (United States)

    Skowron, Stephen T; Chamberlain, Thomas W; Biskupek, Johannes; Kaiser, Ute; Besley, Elena; Khlobystov, Andrei N

    2017-08-15

    The main objective of this Account is to assess the challenges of transmission electron microscopy (TEM) of molecules, based on over 15 years of our work in this field, and to outline the opportunities in studying chemical reactions under the electron beam (e-beam). During TEM imaging of an individual molecule adsorbed on an atomically thin substrate, such as graphene or a carbon nanotube, the e-beam transfers kinetic energy to atoms of the molecule, displacing them from equilibrium positions. Impact of the e-beam triggers bond dissociation and various chemical reactions which can be imaged concurrently with their activation by the e-beam and can be presented as stop-frame movies. This experimental approach, which we term ChemTEM, harnesses energy transferred from the e-beam to the molecule via direct interactions with the atomic nuclei, enabling accurate predictions of bond dissociation events and control of the type and rate of chemical reactions. Elemental composition and structure of the reactant molecules as well as the operating conditions of TEM (particularly the energy of the e-beam) determine the product formed in ChemTEM processes, while the e-beam dose rate controls the reaction rate. Because the e-beam of TEM acts simultaneously as a source of energy for the reaction and as an imaging tool monitoring the same reaction, ChemTEM reveals atomic-level chemical information, such as pathways of reactions imaged for individual molecules, step-by-step and in real time; structures of illusive reaction intermediates; and direct comparison of catalytic activity of different transition metals filmed with atomic resolution. Chemical transformations in ChemTEM often lead to previously unforeseen products, demonstrating the potential of this method to become not only an analytical tool for studying reactions, but also a powerful instrument for discovery of materials that can be synthesized on preparative scale.

  17. Microscopy techniques in flavivirus research.

    Science.gov (United States)

    Chong, Mun Keat; Chua, Anthony Jin Shun; Tan, Terence Tze Tong; Tan, Suat Hoon; Ng, Mah Lee

    2014-04-01

    The Flavivirus genus is composed of many medically important viruses that cause high morbidity and mortality, which include Dengue and West Nile viruses. Various molecular and biochemical techniques have been developed in the endeavour to study flaviviruses. However, microscopy techniques still have irreplaceable roles in the identification of novel virus pathogens and characterization of morphological changes in virus-infected cells. Fluorescence microscopy contributes greatly in understanding the fundamental viral protein localizations and virus-host protein interactions during infection. Electron microscopy remains the gold standard for visualizing ultra-structural features of virus particles and infected cells. New imaging techniques and combinatory applications are continuously being developed to push the limit of resolution and extract more quantitative data. Currently, correlative live cell imaging and high resolution three-dimensional imaging have already been achieved through the tandem use of optical and electron microscopy in analyzing biological specimens. Microscopy techniques are also used to measure protein binding affinities and determine the mobility pattern of proteins in cells. This chapter will consolidate on the applications of various well-established microscopy techniques in flavivirus research, and discuss how recently developed microscopy techniques can potentially help advance our understanding in these membrane viruses. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. FE-SEM, FIB and TEM Study of Surface Deposits of Apollo 15 Green Glass Volcanic Spherules

    Science.gov (United States)

    Ross, Daniel K.; Thomas-Keprta, K. L.; Rahman, Z.; Wentworth, S. J.; McKay, D. S.

    2011-01-01

    Surface deposits on lunar pyroclastic green (Apollo 15) and orange (Apollo 17) glass spherules have been attributed to condensation from the gas clouds that accompanied fire-fountain eruptions. The fire fountains cast molten lava high above the lunar surface and the silicate melt droplets quenched before landing producing the glass beads. Early investigations showed that these deposits are rich in sulfur and zinc. The deposits are extremely fine-grained and thin, so that it was never possible to determine their chemical compositions cleanly by SEM/EDX or electron probe x-ray analysis because most of the excited volume was in the under-lying silicate glass. We are investigating the surface deposits by TEM, using focused ion beam (FIB) microscopy to extract and thin the surface deposits. Here we report on chemical mapping of a FIB section of surface deposits of an Apollo green glass bead 15401using the ultra-high resolution JEOL 2500 STEM located at NASA Johnson Space Center.

  19. Three-Dimensional Reconstruction, by TEM Tomography, of the Ultrastructural Modifications Occurring in Cucumis sativus L. Mitochondria under Fe Deficiency.

    Directory of Open Access Journals (Sweden)

    Gianpiero Vigani

    Full Text Available Mitochondria, as recently suggested, might be involved in iron sensing and signalling pathways in plant cells. For a better understanding of the role of these organelles in mediating the Fe deficiency responses in plant cells, it is crucial to provide a full overview of their modifications occurring under Fe-limited conditions. The aim of this work is to characterize the ultrastructural as well as the biochemical changes occurring in leaf mitochondria of cucumber (Cucumis sativus L. plants grown under Fe deficiency.Mitochondrial ultrastructure was investigated by transmission electron microscopy (TEM and electron tomography techniques, which allowed a three-dimensional (3D reconstruction of cellular structures. These analyses reveal that mitochondria isolated from cucumber leaves appear in the cristae junction model conformation and that Fe deficiency strongly alters both the number and the volume of cristae. The ultrastructural changes observed in mitochondria isolated from Fe-deficient leaves reflect a metabolic status characterized by a respiratory chain operating at a lower rate (orthodox-like conformation with respect to mitochondria from control leaves.To our knowledge, this is the first report showing a 3D reconstruction of plant mitochondria. Furthermore, these results suggest that a detailed characterization of the link between changes in the ultrastructure and functionality of mitochondria during different nutritional conditions, can provide a successful approach to understand the role of these organelles in the plant response to Fe deficiency.

  20. TEM studies of GaN layers grown in non-polar direction: Laterally overgrown and pendeo-epitaxial layers

    Science.gov (United States)

    Liliental-Weber, Z.

    2008-08-01

    The formation of structural defects in GaN grown in non-polar directions is reviewed based on transmission electron microscopy (TEM) studies. Stacking faults (SFs) formed on c-planes and also on prismatic planes bounded by partial dislocations, in addition to full dislocations, are major defects in these layers. Since c-planes are arranged perpendicular to the substrate, these defects propagate to the sample surface through the active areas of the devices and become detrimental for device applications. An established method to decrease the defect density is lateral epitaxial overgrowth (LEO) and pendeo-epitaxy. The measured density of SFs in the seed areas is ˜1.3×10 6 cm -1and in the 'wing' areas ˜1.2×10 4 cm -1; a decrease of almost of two orders of magnitude. For overgrown samples, two opposite wings grow in opposite polar directions: [0 0 0 1] (Ga-growth polarity) and [0 0 0 1] (N-growth polarity) confirmed by convergent beam electron diffraction. Ga-polar wings are wider and often have different height than those grown with N-polarity, therefore planarity of these layers and cracking at the meeting front of two wings often occur. It is shown that two-step growth using MOCVD leads to satisfactory layer planarity.

  1. TEM examination of the interface between Bioglass {sup trademark} /polyethylene composites and human osteoblast cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J. [London Univ. (United Kingdom). IRC Biomedical Materials; Silvio, L. di; Kayser, M. [Inst. of Orthopaedics, Univ. Coll. London Medical School (United Kingdom); Bonfield, W. [London Univ. (United Kingdom). IRC Biomedical Materials; Dept. of Materials Science and Metallurgy, Univ. of Cambridge, Cambridge (United Kingdom)

    2001-07-01

    The interface between Bioglass {sup trademark} reinforced polyethylene (PE) composite and human osteoblast (HOB) cells was studied by transmission electron microscopy (TEM) after 6 weeks in vitro culture. It was found that apatite crystals had been formed around Bioglass {sup trademark} particles of the composite, and there was a direct bonding between the composite and the cells. By contrast, the HOB cell layer was detached from unfilled PE during the sample preparation, although PE was able to support the growth and proliferation of the HOB cells. The results demonstrated that in vitro culture using human osteoblast cells provides valuable information relating to the biological response of the biomaterials. PE is a biocompatible material, but lack of bioactivity. The formation of apatite on Bioglass {sup trademark} provided bonding between the composite and HOB cells, similar to that found on bulk Bioglass {sup trademark} in vivo. Therefore, it is anticipated that the bioactivity of Bioglass {sup trademark} in the Bioglass {sup trademark} /PE composite is retained in vivo. (orig.)

  2. Probing structure in submicronic aqueous assemblies of emulsified microemulsions and charged spherical colloids using SANS and cryo-TEM.

    Science.gov (United States)

    Muller, François; Dégousée, Thibault; Degrouard, Jéril; Brûlet, Annie; Salonen, Anniina

    2015-05-15

    The spatial distribution of charged spherical colloids when used as stabilizers of phytantriol-based emulsified microemulsions (EME, L2 symmetry group) is investigated. The coverage of the lipid-based mesophases by the colloids is monitored using small-angle neutron scattering (SANS) in contrast matching conditions and visualized using cryogenic transmission electron microscopy (cryo-TEM) imaging. The results demonstrate that, despite the stability of the emulsion droplets, very few colloids are ever found on the droplets. The stability of the EMEs is suggested to arise from the very slow ripening rates combined with punctual repulsion against coalescence from the isolated charged colloids on the bigger droplet surfaces. We show the possibility of creating a dense cover around the droplets by partially hydrophobizing the colloids by adsorbing a cationic surfactant on their surface. This opens up the possibilities for further modulation of the colloidal coverage in these systems. This is an interesting route for the design of new Colloid-ISAsome assemblies in which dense protective armors could be advantageous such as controlled delivery. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Transmission electron microscopy analysis of corroded metal waste forms.

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, N. L.

    2005-04-15

    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

  4. Fluorescence confocal microscopy for pathologists.

    Science.gov (United States)

    Ragazzi, Moira; Piana, Simonetta; Longo, Caterina; Castagnetti, Fabio; Foroni, Monica; Ferrari, Guglielmo; Gardini, Giorgio; Pellacani, Giovanni

    2014-03-01

    Confocal microscopy is a non-invasive method of optical imaging that may provide microscopic images of untreated tissue that correspond almost perfectly to hematoxylin- and eosin-stained slides. Nowadays, following two confocal imaging systems are available: (1) reflectance confocal microscopy, based on the natural differences in refractive indices of subcellular structures within the tissues; (2) fluorescence confocal microscopy, based on the use of fluorochromes, such as acridine orange, to increase the contrast epithelium-stroma. In clinical practice to date, confocal microscopy has been used with the goal of obviating the need for excision biopsies, thereby reducing the need for pathological examination. The aim of our study was to test fluorescence confocal microscopy on different types of surgical specimens, specifically breast, lymph node, thyroid, and colon. The confocal images were correlated to the corresponding histological sections in order to provide a morphologic parallel and to highlight current limitations and possible applications of this technology for surgical pathology practice. As a result, neoplastic tissues were easily distinguishable from normal structures and reactive processes such as fibrosis; the use of fluorescence enhanced contrast and image quality in confocal microscopy without compromising final histologic evaluation. Finally, the fluorescence confocal microscopy images of the adipose tissue were as accurate as those of conventional histology and were devoid of the frozen-section-related artefacts that can compromise intraoperative evaluation. Despite some limitations mainly related to black/white images, which require training in imaging interpretation, this study confirms that fluorescence confocal microscopy may represent an alternative to frozen sections in the assessment of margin status in selected settings or when the conservation of the specimen is crucial. This is the first study to employ fluorescent confocal microscopy on

  5. Qualidade de vida do paciente submetido à Microcirurgia Endoscópica Transanal (TEM Quality of life after Transanal Endoscopic Microsurgery (TEM

    Directory of Open Access Journals (Sweden)

    Roberto da Silveira Moraes

    2007-03-01

    Full Text Available RACIONAL: A Microcirurgia Endoscópica Transanal (TEM é procedimento minimamente invasivo para o tratamento de tumores retais selecionados. Atualmente, existe crescente interesse médico na medida quantitativa da qualidade de vida. OBJETIVO: Avaliar a qualidade de vida dos pacientes submetidos a TEM no Serviço de Cirurgia do Aparelho Digestivo no Hospital de Clínicas da Universidade Federal do Paraná. MÉTODOS: Trata-se de um estudo observacional prospectivo e de coorte da avaliação da qualidade de vida após TEM. Trinta e quatro pacientes responderam a um questionário composto de 14 questões, abordando aspectos pós-operatórios e laborais. Dirigiam-se elas para levantar dados principalmente sobre: o consentimento informado; a dor experimentada após a operação; a capacidade de o paciente caminhar no período pós-operatório; o período para retorno às atividades habituais; a satisfação com a ausência de cicatriz pós-operatória; a incontinência no pós-operatório; se recomendaria a operação a um familiar ou conhecido. RESULTADOS: Todos os 34 pacientes relataram ter sido adequadamente informados sobre o procedimento. Ausência de dor pós-operatória foi observada em 82,5% e todos se mostraram capazes de deambular no 1º dia do pós-operatório. O retorno às atividades habituais deu-se em média sete dias após o procedimento. Somente cinco pacientes (14,70% apresentaram incontinência fecal transitória, não maior que uma semana. Três pacientes (8,82% necessitaram de re-internação, sendo dois por tumores residuais e outro por recidiva tumoral. Dois pacientes (5,88% referiram modificação temporária na vida sexual após a cirurgia e 97,05% indicariam a TEM a um familiar ou amigo. O período médio de internação foi de três dias. CONCLUSÃO: Os pacientes apresentaram boa evolução, com pouca dor pós-operatória, curto período de internação e baixo índice de complicações, mostrando satisfação e adequada

  6. Combined interpretation of SkyTEM and high-resolution seismic data

    DEFF Research Database (Denmark)

    Høyer, Anne-Sophie; Lykke-Andersen, Holger; Jørgensen, Flemming Voldum

    2011-01-01

    on the resistivity log, synthetic SkyTEM responses were calculated with a varying number of gate-times in order to illustrate the effect of the noise-level. At the exploration well geophysical data were compared to the lithological log; in general there is good agreement. The same tendency was recognised when Sky...... made based on AEM (SkyTEM) and high-resolution seismic data from an area covering 10 km2 in the western part of Denmark. As support for the interpretations, an exploration well was drilled to provide lithological and logging information in the form of resistivity and vertical seismic profiling. Based......TEM results from the area were superposed onto seismic sections. Hence, comprehensive geological knowledge is necessary in order to introduce layer boundaries from one method interactively in the data handling of the other. However, in cases where resistivity transitions are positively correlated...

  7. Towards understanding the influence of electron-gas interactions on imaging in an environmental TEM

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal; Boothroyd, Chris; Beleggia, Marco

    2011-01-01

    improved the point resolution to the sub-Ångström level [1] and reduced image delocalization, allowing images of surface and interface structures to be interpreted more directly [2]. However, when gas is present in the microscope the path of electrons along the column is modified due to gas......-electron scattering [3]. In general there are two approaches for performing TEM experiments in the presence of gases. These approaches are based on a differential pumping scheme and the closed cell TEM holder approach and each has its advantages and disadvantages. In the closed cell approach, gas molecules...... are confined to a thin (typically 50-200 μm thick) slab around the sample, but the electrons interact with the window material (e.g. C, SiN) as well as with the gas and the sample. In addition, the field of view is typically smaller than in a conventional TEM and a limited range of sample geometries can...

  8. 2.5D Modeling of TEM Data Applied to Hidrogeological Studies in PARANÁ Basin, Brazil

    Science.gov (United States)

    Bortolozo, C. A.; Porsani, J. L.; Santos, F. M.

    2013-12-01

    The transient electromagnetic method (TEM) is used all over the world and has shown great potential in hydrological, hazardous waste site characterization, mineral exploration, general geological mapping, and geophysical reconnaissance. However, the behavior of TEM fields are very complex and is not yet fully understood. Forward modeling is one of the most common and effective methods to understand the physical behavior and significance of the electromagnetics responses of a TEM sounding. Until now, there are a limited number of solutions for the 2D forward problem for TEM. More rare are the descriptions of a three-component response of a 3D source over 2D earth, which is the so-called 2.5D. The 2.5D approach is more realistic than the conventional 2D source previous used, once normally the source cannot be realistic represented for a 2D approximation (normally source are square loops). At present the 2.5D model represents the only way of interpreting TEM data in terms of a complex earth, due to the prohibitive amount of computer time and storage required for a full 3D model. In this work we developed a TEM modeling program for understanding the different responses and how the magnetic and electric fields, produced by loop sources at air-earth interface, behave in different geoelectrical distributions. The models used in the examples are proposed focusing hydrogeological studies, once the main objective of this work is for detecting different kinds of aquifers in Paraná sedimentary basin, in São Paulo State - Brazil. The program was developed in MATLAB, a widespread language very common in the scientific community.

  9. TEM Study of the Growth Mechanism, Phase Transformation, and Core/shell Structure of Semiconductor Nanowires

    Science.gov (United States)

    Wong, Tai Lun

    In this thesis, the fabrication and characterization of one-dimensional nanostructures have been studied systematically to understand the growth mechanism and structure transformation of one-dimensional nanostructures. The growth behavior of the ultrathin ZnSe nanowires with diameter less than 60 nm was found to be different from classical vapor-liquid-solid (VLS) process. The growth rate increases when the diameter of nanowires decreases, in contrast to the classical VLS process in which the growth rate increases with the diameter. The nucleation, initial growth, growth rates, defects, interface structures and growth direction of the nanowires were investigated by high resolution transmission electron microscopy (HRTEM). We found the structure and growth direction of ultra-thin nanowires are highly sensitive to growth temperatures and diameters of nanowires. At a low growth temperature (380°C), the growth direction for most nanowires is along . Planar defects were found throughout the nanowires. At a high growth temperature (530°C), uniform nanowires with diameters around 10nm were grown along and directions, and the nanowires with diameters larger than 20nm were mainly grown along direction. The possible growth mechanism of ultrathin nanowires was proposed by combining the solid catalytic growth with the interface diffusion theory, in order to explain how the growth temperature and the size of the catalysts influent the morphology, growth direction and growth rate of ultrathin nanowires. Structural and phase transformation of a nickel coated Si nanowire to NiSi2/SiC core-shell nanowire heterostructures has been investigated by the in-situ Transmission Electron Microscope (TEM). The phase transformation is a single-site nucleation process and therefore a single crystalline NiSi2 core resulted in the core-shell nanowire heterostructures. The transformation of the Si nanowire to NiSi2/SiC core-shell nanowire heterostructures was extremely fast and completed

  10. Integrated Transmission Electron and Single-Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle.

    Science.gov (United States)

    Hendriks, Frank C; Mohammadian, Sajjad; Ristanović, Zoran; Kalirai, Sam; Meirer, Florian; Vogt, Eelco T C; Bruijnincx, Pieter C A; Gerritsen, Hans C; Weckhuysen, Bert M

    2018-01-02

    Establishing structure-activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single-molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure-reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF-TEM high-resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM-derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  11. Transmission electron microscopy study of Listeria monocytogenes serotype 1/2a cells exposed to sublethal heat stress and carvacrol

    Science.gov (United States)

    The objective of this study was to investigate the morphological changes that occurred in Listeria monocytogenes serotype 1/2a cells as visualized by transmission electron microscopy (TEM) after exposure to sublethal heat stress at 48°C for 60 min and in combination with lethal concentration of carv...

  12. Environmental TEM in the in situ Toolbox

    DEFF Research Database (Denmark)

    Wagner, Jakob Birkedal

    Studies of materials using in situ techniques usually involve a compromise of the in situ conditions in order to fulfil the requirements compatible with the instrumentation for characterization. These requirements include sample geometry, temperature, gas environment etc. Environmental TEM depends...... the techniques to the microscope. A dedicated custom TEM specimen holder containing two optical fibres, five electrical contacts, a fixed miniaturized optical bench for light handling and a heating element has been designed. A system of pre-aligned mirrors and a MEMS heater are implemented in the holder...

  13. Measuring and Tailoring the Structure of Two-Dimensional Materials by Transmission Electron Microscopy

    DEFF Research Database (Denmark)

    Thomsen, Joachim Dahl

    of these sources of scattering is, therefore, important for industrial applications as well as fundamental scientific purposes. Transmission electron microscopy (TEM) is an excellent tool for structural characterisation of 2D materials because of its sub-angstrom resolution, and potential for adding stimuli like...... heat, electrical biasing, and studying the interaction with gas molecules. In this project, TEM has been used to measure the structure and also to physically pattern graphene on the nanoscale. First, the design, fabrication and characterisation of TEM sample carriers for simultaneous in-situ heating......As the critical dimensions of electronic devices decrease in size, the nanoscale structure becomes important for the electronic properties. Two-dimensional (2D) materials, with a thickness down to one atom, are very affected by disorder. Any type of disorder in graphene, including lattice disorder...

  14. Processing and characterization of canine mixed mammary tumor using transmission electron microscopy.

    Science.gov (United States)

    Audrey, Beltrán; Alexis, Debut; Andrea, Vaca; Julio, Ortiz; Freddy, Proaño-Pérez

    2017-11-01

    Canine mammary gland tumors represent the second most frequent type of neoplasm in dogs, being an important problem within veterinary medical field. Canine mixed mammary tumors are the most common; the use of a transmission electron microscope (TEM) can contribute as a tool in its diagnosis by determining the characteristics of cellular components from numerous neoplasms. The aim of this study was to characterize cytologically canine mammary mixed tumor by the use of the TEM. A biopsy collected from an 11 years old bitch Shih-Tzu and analyzed by histopathology was used for ultrastructural analysis. Specimens obtained were double stained using uranyl acetate and lead citrate prior to observation in the TEM. The protocol established to transmission electron microscopy observation allowed the identification of main cellular characteristics of canine mixed mammary tumors; however, it was not possible a detailed visualization of the organelles due to the preservation of the biopsy in formaldehyde. © 2017 Wiley Periodicals, Inc.

  15. Holography and transmission electron microscopy

    OpenAIRE

    Matteucci, G.; Pozzi, G.; Tonomura, A.

    1993-01-01

    The basic principles and methods of off-axis electron holography are presented and illustrated by means of three examples related to its application in high resolution electron microscopy and the investigation of electric and magnetic fields in thin specimens.

  16. Fluorescence Microscopy of Single Molecules

    Science.gov (United States)

    Zimmermann, Jan; van Dorp, Arthur; Renn, Alois

    2004-01-01

    The investigation of photochemistry and photophysics of individual quantum systems is described with the help of a wide-field fluorescence microscopy approach. The fluorescence single molecules are observed in real time.

  17. Fluorescence lifetime imaging microscopy (FLIM).

    NARCIS (Netherlands)

    van Munster, E.B.; Gadella, Th.W.J.; Rietdorf, J.

    2005-01-01

    Fluorescence lifetime imaging microscopy (FLIM) is a technique to map the spatial distribution of nanosecond excited state lifetimes within microscopic images. FLIM systems have been implemented both in the frequency domain, using sinusoidally intensity-modulated excitation light and modulated

  18. Filter-Dense Multicolor Microscopy

    National Research Council Canada - National Science Library

    Kijani, Siavash; Yrlid, Ulf; Heyden, Maria; Levin, Malin; Borén, Jan; Fogelstrand, Per

    2015-01-01

    .... However, because of the risk of bleed-through signals between fluorochromes, standard multicolor microscopy is restricted to a maximum of four fluorescence channels, including one for nuclei staining...

  19. On the structural affinity of macromolecules with different biological properties: molecular dynamics simulations of a series of TEM-1 mutants.

    Science.gov (United States)

    Giampaolo, Alessia Di; Mazza, Fernando; Daidone, Isabella; Amicosante, Gianfranco; Perilli, Mariagrazia; Aschi, Massimiliano

    2013-07-12

    Molecular Dynamics simulations have been carried out in order to provide a molecular rationalization of the biological and thermodynamic differences observed for a class of TEM β-lactamases. In particular we have considered the TEM-1(wt), the single point mutants TEM-40 and TEM-19 representative of IRT and ESBL classes respectively, and TEM-1 mutant M182T, TEM-32 and TEM-20 which differ from the first three for the additional of M182T mutation. Results indicate that most of the thermodynamic, and probably biological behaviour of these systems arise from subtle effects which, starting from the alterations of the local interactions, produce drastic modifications of the conformational space spanned by the enzymes. The present study suggests that systems showing essentially the same secondary and tertiary structure may differentiate their chemical-biological activity essentially (and probably exclusively) on the basis of the thermal fluctuations occurring in their physiological environment. Copyright © 2013 Elsevier Inc. All rights reserved.

  20. Monolithic Chip System with a Microfluidic Channel for In Situ Electron Microscopy of Liquids

    DEFF Research Database (Denmark)

    Jensen, Eric; Burrows, Andrew; Mølhave, Kristian

    2014-01-01

    sandwiched microchips with thin membranes. We report on a new microfabricated chip system based on a monolithic design that enables membrane geometry on the scale of a few micrometers. The design is intended to reduce membrane deflection when the system is under pressure, a micro fluidic channel for improved...... flow geometry, and a better space angle for auxiliary detectors such as energy-dispersive X-ray spectroscopy. We explain the system design and fabrication and show the first successful TEM images of liquid samples in the chips.......Electron microscopy of enclosed liquid samples requires the thinnest possible membranes as enclosing windows as well as nanoscale liquid sample thickness to achieve the best possible resolution. Today liquid sample systems for transmission electron microscopy (TEM) are typically made from two...

  1. Revealing 3D Ultrastructure and Morphology of Stem Cell Spheroids by Electron Microscopy.

    Science.gov (United States)

    Jaros, Josef; Petrov, Michal; Tesarova, Marketa; Hampl, Ales

    2017-01-01

    Cell culture methods have been developed in efforts to produce biologically relevant systems for developmental and disease modeling, and appropriate analytical tools are essential. Knowledge of ultrastructural characteristics represents the basis to reveal in situ the cellular morphology, cell-cell interactions, organelle distribution, niches in which cells reside, and many more. The traditional method for 3D visualization of ultrastructural components, serial sectioning using transmission electron microscopy (TEM), is very labor-intensive due to contentious TEM slice preparation and subsequent image processing of the whole collection. In this chapter, we present serial block-face scanning electron microscopy, together with complex methodology for spheroid formation, contrasting of cellular compartments, image processing, and 3D visualization. The described technique is effective for detailed morphological analysis of stem cell spheroids, organoids, as well as organotypic cell cultures.

  2. Transmission electron microscopy, fluorescence microscopy, and confocal raman microscopic analysis of ultrastructural and compositional heterogeneity of Cornus alba L. wood cell wall.

    Science.gov (United States)

    Ma, Jianfeng; Ji, Zhe; Zhou, Xia; Zhang, Zhiheng; Xu, Feng

    2013-02-01

    Transmission electron microscopy (TEM), fluorescence microscopy, and confocal Raman microscopy can be used to characterize ultrastructural and compositional heterogeneity of plant cell walls. In this study, TEM observations revealed the ultrastructural characterization of Cornus alba L. fiber, vessel, axial parenchyma, ray parenchyma, and pit membrane between cells, notably with the ray parenchyma consisting of two well-defined layers. Fluorescence microscopy evidenced that cell corner middle lamella was more lignified than adjacent compound middle lamella and secondary wall with variation in lignification level from cell to cell. In situ Raman images showed that the inhomogeneity in cell wall components (cellulose and lignin) among different cells and within morphologically distinct cell wall layers. As the significant precursors of lignin biosynthesis, the pattern of coniferyl alcohol and aldehyde (joint abbreviation Lignin-CAA for both structures) distribution in fiber cell wall was also identified by Raman images, with higher concentration occurring in the fiber secondary wall where there was the highest cellulose concentration. Moreover, noteworthy was the observation that higher concentration of lignin and very minor amounts of cellulose were visualized in the pit membrane areas. These complementary microanalytical methods provide more accurate and complete information with regard to ultrastructural and compositional characterization of plant cell walls.

  3. Demonstration of correlative atomic force and transmission electron microscopy using actin cytoskeleton.

    Science.gov (United States)

    Yamada, Yutaro; Konno, Hiroki; Shimabukuro, Katsuya

    2017-01-01

    In this study, we present a new technique called correlative atomic force and transmission electron microscopy (correlative AFM/TEM) in which a targeted region of a sample can be observed under AFM and TEM. The ultimate goal of developing this new technique is to provide a technical platform to expand the fields of AFM application to complex biological systems such as cell extracts. Recent advances in the time resolution of AFM have enabled detailed observation of the dynamic nature of biomolecules. However, specifying molecular species, by AFM alone, remains a challenge. Here, we demonstrate correlative AFM/TEM, using actin filaments as a test sample, and further show that immuno-electron microscopy (immuno-EM), to specify molecules, can be integrated into this technique. Therefore, it is now possible to specify molecules, captured under AFM, by subsequent observation using immuno-EM. In conclusion, correlative AFM/TEM can be a versatile method to investigate complex biological systems at the molecular level.

  4. Synergy between transmission electron microscopy and powder diffraction: application to modulated structures.

    Science.gov (United States)

    Batuk, Dmitry; Batuk, Maria; Abakumov, Artem M; Hadermann, Joke

    2015-04-01

    The crystal structure solution of modulated compounds is often very challenging, even using the well established methodology of single-crystal X-ray crystallography. This task becomes even more difficult for materials that cannot be prepared in a single-crystal form, so that only polycrystalline powders are available. This paper illustrates that the combined application of transmission electron microscopy (TEM) and powder diffraction is a possible solution to the problem. Using examples of anion-deficient perovskites modulated by periodic crystallographic shear planes, it is demonstrated what kind of local structural information can be obtained using various TEM techniques and how this information can be implemented in the crystal structure refinement against the powder diffraction data. The following TEM methods are discussed: electron diffraction (selected area electron diffraction, precession electron diffraction), imaging (conventional high-resolution TEM imaging, high-angle annular dark-field and annular bright-field scanning transmission electron microscopy) and state-of-the-art spectroscopic techniques (atomic resolution mapping using energy-dispersive X-ray analysis and electron energy loss spectroscopy).

  5. Characterisation of internal morphologies in electrospun fibers by X-ray tomographic microscopy

    Science.gov (United States)

    Nygaard, Jens Vinge; Uyar, Tamer; Chen, Menglin; Cloetens, Peter; Kingshott, Peter; Besenbacher, Flemming

    2011-09-01

    Electrospun fabrics for use in, for example, tissue engineering, wound dressings, textiles, filters and membranes have attracted a lot of attention due to their morphological nanoscale architectures which enhance their physical properties. A thorough detailed internal morphological study has been performed on electrospun polystyrene (PS) fibers produced from dimethylformamide (DMF) solutions. Investigations by transmission electron microscopy (TEM) and thorough studies for the first time by synchrotron based X-ray tomographic microscopy (XTM) revealed that the individual electrospun PS fibers and beads have a graded density and in some cases even an internal porous structure.

  6. Determination of the Projected Atomic Potential by Deconvolution of the Auto-Correlation Function of TEM Electron Nano-Diffraction Patterns

    Directory of Open Access Journals (Sweden)

    Liberato De Caro

    2016-11-01

    Full Text Available We present a novel method to determine the projected atomic potential of a specimen directly from transmission electron microscopy coherent electron nano-diffraction patterns, overcoming common limitations encountered so far due to the dynamical nature of electron-matter interaction. The projected potential is obtained by deconvolution of the inverse Fourier transform of experimental diffraction patterns rescaled in intensity by using theoretical values of the kinematical atomic scattering factors. This novelty enables the compensation of dynamical effects typical of transmission electron microscopy (TEM experiments on standard specimens with thicknesses up to a few tens of nm. The projected atomic potentials so obtained are averaged on sample regions illuminated by nano-sized electron probes and are in good quantitative agreement with theoretical expectations. Contrary to lens-based microscopy, here the spatial resolution in the retrieved projected atomic potential profiles is related to the finer lattice spacing measured in the electron diffraction pattern. The method has been successfully applied to experimental nano-diffraction data of crystalline centrosymmetric and non-centrosymmetric specimens achieving a resolution of 65 pm.

  7. Monolayer to MTS: using SEM, HIM, TEM and SERS to compare morphology, nanosensor uptake and redox potential in MCF7 cells

    Science.gov (United States)

    Jamieson, L. E.; Bell, A. P.; Harrison, D. J.; Campbell, C. J.

    2015-06-01

    Cellular redox potential is important for the control and regulation of a vast number of processes occurring in cells. When the fine redox potential balance within cells is disturbed it can have serious consequences such as the initiation or progression of disease. It is thought that a redox gradient develops in cancer tumours where the peripheral regions are well oxygenated and internal regions, further from vascular blood supply, become starved of oxygen and hypoxic. This makes treatment of these areas more challenging as, for example, radiotherapy relies on the presence of oxygen. Currently techniques for quantitative analysis of redox gradients are limited. Surface enhanced Raman scattering (SERS) nanosensors (NS) have been used to detect redox potential in a quantitative manner in monolayer cultured cells with many advantages over other techniques. This technique has considerable potential for use in multicellular tumour spheroids (MTS) - a three dimensional (3D) cell model which better mimics the tumour environment and gradients that develop. MTS are a more realistic model of the in vivo cellular morphology and environment and are becoming an increasingly popular in vitro model, replacing traditional monolayer culture. Imaging techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM) and helium ion microscopy (HIM) were used to investigate differences in morphology and NS uptake in monolayer culture compared to MTS. After confirming NS uptake, the first SERS measurements revealing quantitative information on redox potential in MTS were performed.

  8. Static shift correction of MT data in Tohoku district using TEM soundings; TEM ho data wo mochiita Tohoku chiho MT ho data no statistic shift hosei

    Energy Technology Data Exchange (ETDEWEB)

    Kawakami, N.; Kumekawa, Y.; Miura, Y.; Takasugi, S. [GERD Geothermal Energy Research and Development Co. Ltd., Tokyo (Japan); Fujinawa, Y. [National Research Institute for Disaster Prevention, Tsukuba (Japan)

    1997-05-27

    There is a possibility that the wide-band MT observation data obtained in the central part of Tohoku district include the static shift effect. To grasp the static shift effect in the MT data, the TEM soundings were conducted at all the site where the MT data were measured. The TEM sounding system was developed for the shallow survey depth ranging from 5 m to 150 m. When showing the measured results on the histogram, it was found that the static shifts were concentrated in the vicinity of zero. About 70% of the data was below 0.2 decade. Only a slight static shift effect was observed. This means that the results obtained by the two-dimensional analysis are plausible. Especially, the static shift around plain was small. Therefore, the current results around the plain were trustful. On the other hand, the static shift in the mountainous area was rather large. Accordingly, the results around the mountainous area should be carefully treated. 7 refs., 10 figs.

  9. Fault detection by Turam TEM survey. Numerical model studies and a case history; TEM ho Turam sokutei haichi ni yoru danso kenshutsu no kokoromi. Model keisan to jisshirei

    Energy Technology Data Exchange (ETDEWEB)

    Wada, K.; Tsutsui, T. [Mitsui Mineral Development Engineering Co. Ltd., Tokyo (Japan); Ito, T. [Chiba Univ., Chiba (Japan). Faculty of Science; Takeuchi, A. [Toyama University, Toyama (Japan). Faculty of Science; He, P. [Power Reactor and Nuclear fuel Development Corp., Tokyo (Japan)

    1997-05-27

    With an objective to detect faults estimated to exist along the Shigesumi valley in the Kamioka mine, discussions were given by using electromagnetic survey, which uses the Turam measurement arrangement based on the TEM method, and three-dimensional model calculations. The Turam measurement arrangement, which installs transmission loop fixedly, is used to identify nature and distribution of electrically conductive objects upon noticing abnormal portions in magnetic fields in the measurement data. In the model calculation, the plate model calculation method and the FDTD method were used, and so was the calculation code TEM3DL. The result revealed that strong topographical influence is seen from steep V-shaped valley existing along the traverse line in the measurement data, but an abnormal resistivity band accompanying remarkable distortion in the curve was detected. According to the result of the model calculation, anomaly detection may be found difficult in locations where a low resistivity band has not grown enough locally. It was possible from these facts to assume a model in which the low resistivity band exists directly below the Shigesumi valley, suggesting existence of faults. 2 refs., 8 figs.

  10. Improvement of microtome cutting process of carbon nanotube composite sample preparation for TEM analysis

    Science.gov (United States)

    Trayner, Sarah

    As research progresses towards nanoscale materials, there has become a need for a more efficient and effective way to obtain ultra-thin samples for imaging under transmission electron microscope (TEM) for atomic resolution analysis. There are various methods used to obtain thin samples (resin and graphite crystalline packing. UD IM7/BMI composite TEM results did not reveal an interfacial region resulting in a need for even thinner sliced cross sections. TEM results for the single-layer CNT BP/epoxy nanocomposite revealed the alignment direction of the nanotubes and numerous stacks of CNT bundles. In addition, there was visible flattening of CNT packing into dumbbell shapes similar to results obtain by Alan Windle. TEM results for the 3-layer CNT BP/BMI nanocomposite revealed uniformly cut resin. However, when the diamond knife reached graphite crystalline regions, the nanotube either became deformed into a cone-like structure, was cut at a thicker thickness than the resin, or folded over onto itself. This is most likely a result of the nanotubes high mechanical properties in response to the stress of cutting.

  11. Sub-nanometer stable precision MEMS clamping mechanism maintaining clamp force unpowered for TEM application

    NARCIS (Netherlands)

    Brouwer, Dannis Michel; de Jong, B.R.; Soemers, Herman; van Dijk, Johannes

    2006-01-01

    A design is presented for a relatively large force (0.5 mN) high-precision MEMS clamping mechanism. The clamp is a part of a MEMS transmission electron microscope (TEM) sample manipulator, which needs to be fixed unpowered once positioned. The elastic deformation of the clamp suspension has been

  12. In-Situ TEM Investigation of Deformation Behavior of Metallic Glass Pillars

    NARCIS (Netherlands)

    Chen, C. Q.; Pei, Y. T.; De Hosson, J. Th. M.; Tamura, N; Minor, A; Murray, C; Friedman, L

    2009-01-01

    We show results of in situ TEM (transmission electron microscope) quantitative investigations on the compression behaviors of amorphous micropillars fabricated by focused ion beam from Cu(47)Ti(33)Zr(11)Ni(6)Sn(2)Si(1) metallic glass (MG) ribbon. Pillars with well defined gauge sections and tip

  13. First detection of bla TEM, SHV and CTX-M among Gram negative ...

    African Journals Online (AJOL)

    user

    2015-04-08

    Apr 8, 2015 ... http://www.academicjournals.org/AJB. African Journal of Biotechnology. Full Length Research Paper. First detection of bla TEM, SHV and CTX-M among. Gram negative bacilli exhibiting extended spectrum β- lactamase phenotype isolated at University Hospital. Center, Yalgado Ouedraogo, Ouagadougou, ...

  14. TEM and EELS studies of microwave-irradiation synthesis of bimetallic platinum nanocatalysts

    CSIR Research Space (South Africa)

    Mathe, NR

    2014-01-01

    Full Text Available to conventional methods. In this work, microwave-irradiation was used to produce platinum-cobalt (Pt-Co) and platinum-nickel (Pt-Ni) nanoparticles for use as electrocatalysts in the methanol oxidation reaction. High resolution TEM imaging and EELS studies revealed...

  15. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K; Boyes, E D; Gai, P L [York JEOL Nanocentre (United Kingdom); Shiju, N R; Brown, D R, E-mail: pgb500@york.ac.u [Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield, HD1 3DH (United Kingdom)

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  16. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Science.gov (United States)

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 Å = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  17. MICROORGANISMS FOUND IN SECONDARY CATARACT MATERIAL OF ECCE PATIENTS, A STUDY WITH SEM AND TEM

    NARCIS (Netherlands)

    KALICHARAN, D; JONGEBLOED, WL; LOS, LI; WORST, JGF

    1993-01-01

    Globular secondary cataract material, removed from 24 patients with ECCE after ophthalmic cleaning of the anterior capsule, were investigated with SEM and TEM. Besides spherical, somewhat oval shaped bodies of various shape and size comparable with those found in cataractous lenses, (an)aerobic

  18. TEM study of continuous precipitation in Mg-9 Wt%Al-l Wt%Zn alloy

    NARCIS (Netherlands)

    Celotto, S

    2000-01-01

    The development of continuous precipitate morphology in heat-treated Mg-9 wt%Al-1 wt%Zn alloy (AZ91) for a range of ageing temperatures is investigated in detail using TEM. The matrix/precipitate orientation relationships (ORs), sizes, shapes and the number of precipitates per unit volume (N-V) are

  19. In situ TEM and STEM studies of reversible electromigration in thin palladium–platinum bridges

    NARCIS (Netherlands)

    Kozlova, T.; Rudneva, M.; Zandbergen, H.W.

    2013-01-01

    We investigated the reversible electromigration in Pd–Pt nanobridges by means of in situ electron microscopy. Real-time nanometer-scale imaging with scanning transmission electron microscopy was used to determine the material transport. For high current densities (3–5 × 107 A cm?2), material

  20. Nanoparticle suspensions enclosed in methylcellulose: a new approach for quantifying nanoparticles in transmission electron microscopy

    OpenAIRE

    Christian Hacker; Jalal Asadi; Christos Pliotas; Sophie Ferguson; Lee Sherry; Phedra Marius; Javier Tello; David Jackson; James Naismith; John Milton Lucocq

    2016-01-01

    Nanoparticles are of increasing importance in biomedicine but quantification is problematic because current methods depend on indirect measurements at low resolution. Here we describe a new high-resolution method for measuring and quantifying nanoparticles in suspension. It involves premixing nanoparticles in a hydrophilic support medium (methylcellulose) before introducing heavy metal stains for visualization in small air-dried droplets by transmission electron microscopy (TEM). The use of m...

  1. Characterization nanoparticles-based vaccines and vaccine candidates: a Transmission Electron Microscopy study

    Directory of Open Access Journals (Sweden)

    I. Menéndez I

    2016-05-01

    Full Text Available Transmission Electron Microscopy (TEM is a valuable tool for the biotech industry. This paper summarizes some of the contributions of MET in the characterization of the recombinant antigens are part of vaccines or vaccine candidates obtained in the CIGB. It mentions the use of complementary techniques MET (Negative staining, and immunoelectron that enhance visualization and ultrastructural characterization of the recombinant proteins obtained by Genetic Engineering.

  2. Studying the Kinetics of Crystalline Silicon Nanoparticle Lithiation with In Situ Transmission Electron Microscopy

    KAUST Repository

    McDowell, Matthew T.

    2012-09-04

    In situ transmission electron microscopy (TEM) is used to study the electrochemical lithiation of high-capacity crystalline Si nanoparticles for use in Li-ion battery anodes. The lithiation reaction slows down as it progresses into the particle interior, and analysis suggests that this behavior is due not to diffusion limitation but instead to the influence of mechanical stress on the driving force for reaction. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Transmission electron microscopy study on silicon nitride/stainless steel bonded interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Poza, P. [Departamento de Ciencia e Ingenieria de los Materiales, Universidad Rey Juan Carlos, 28933 Mostoles, Madrid (Spain); Miranzo, P. [Institute of Ceramics and Glass, CSIC, Campus de Cantoblanco, 28049 Madrid (Spain); Osendi, M.I. [Institute of Ceramics and Glass, CSIC, Campus de Cantoblanco, 28049 Madrid (Spain)], E-mail: miosendi@icv.csic.es

    2008-11-28

    The reaction zone of a diffusion bonded Si{sub 3}N{sub 4}/stainlees steel (ss) interface formed at 1100 deg. C was analyzed by transmission electron microscopy and X-ray diffraction (XRD). Besides the formation of various iron silicides, iron nitride and chromium nitride phases detected by XRD, Cr{sub 3}Ni{sub 5}Si{sub 2} crystals were identified at the interface by TEM.

  4. A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes.

    Science.gov (United States)

    Rubino, Stefano; Akhtar, Sultan; Leifer, Klaus

    2016-02-01

    We present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I 0(t), as a function of the specimen thickness t (tgraphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.

  5. Creating standards for absolute quantification of Coxiella burnetii in real-time PCR--a comparative study based on transmission electron microscopy.

    Science.gov (United States)

    Sting, Reinhard; Molz, Kerstin; Hoferer, Marc

    2015-01-01

    Quantitative standards are a prerequisite for quality control and quantification of pathogens. In this study the creation of quantitative standards for use in qPCR is described using the pathogen Coxiella burnetii. Quantification of Coxiella burnetii particles by transmission electron microscopy (TEM) was used as primary standard and compared with data obtained by light microscopy as well as genome equivalents (GE) and plasmid units (recombinant plasmid). Based on pathogen quantification using TEM and light microscopy, pathogen detection limits of 6 and 2 C. burnetii particles could be determined per com1 qPCR reaction, respectively. In comparison, the detection limits were 17 and 13 pathogen units using GE and plasmid units, respectively. The standard generated by TEM can be used as gold standard for universal application due to high accuracy, quantitative control of the producing process and supplying intact pathogen particles. Copyright © 2014 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

  6. Changes in background aerosol composition in Finland during polluted and clean periods studied by TEM/EDX individual particle analysis

    Directory of Open Access Journals (Sweden)

    J. V. Niemi

    2006-01-01

    Full Text Available Aerosol samples were collected at a rural background site in southern Finland in May 2004 during pollution episode (PM1~16 µg m−3, backward air mass trajectories from south-east, intermediate period (PM1~5 µg m−3, backtrajectories from north-east and clean period (PM1~2 µg m−3, backtrajectories from north-west/north. The elemental composition, morphology and mixing state of individual aerosol particles in three size fractions were studied using transmission electron microscopy (TEM coupled with energy dispersive X-ray (EDX microanalyses. The TEM/EDX results were complemented with the size-segregated bulk chemical measurements of selected ions and organic and elemental carbon. Many of the particles in PM0.2–1 and PM1–3.3 size fractions were strongly internally mixed with S, C and/or N. The major particle types in PM0.2–1 samples were 1 soot and 2 (ammoniumsulphates and their mixtures with variable amounts of C, K, soot and/or other inclusions. Number proportions of those two particle groups in PM0.2–1 samples were 0–12% and 83–97%, respectively. During the pollution episode, the proportion of Ca-rich particles was very high (26–48% in the PM1–3.3 and PM3.3–11 samples, while the PM0.2–1 and PM1–3.3 samples contained elevated proportions of silicates (22–33%, metal oxides/hydroxides (1–9% and tar balls (1–4%. These aerosols originated mainly from polluted areas of Eastern Europe, and some open biomass burning smoke was also brought by long-range transport. During the clean period, when air masses arrived from the Arctic Ocean, PM1–3.3 samples contained mainly sea salt particles (67–89% with a variable rate of Cl substitution (mainly by NO3−. During the intermediate period, the PM1–3.3 sample contained porous (sponge-like Na-rich particles (35% with abundant S, K and O. They might originate from the burning of wood pulp wastes of paper industry. The proportion of biological particles and C-rich fragments

  7. Operator Training and TEMS Support: A Survey of Unit Leaders in Northern and Central California.

    Science.gov (United States)

    Young, Jason B; Galante, Joseph M; Sena, Matthew J

    2013-01-01

    Members of Special Weapons and Tactics (SWAT) teams routinely work in high-risk tactical situations. Awareness of the benefit of Tactical Emergency Medical Support (TEMS) is increasing but not uniformly emphasized. To characterize the current regional state of tactical medicine and identify potential barriers to more widespread implementation. A multiple-choice survey was administered to SWAT team leaders of 22 regional agencies in northern and central California. Questions focused on individual officer self-aid and buddy care training, the use and content of individual first aid kits (IFAKs), and the operational inclusion of a dedicated TEMS provider. Respondents included city police (54%), local county sheriff (36%), state law enforcement (5%), and federal law enforcement (5%). RESULTS showed that 100% of respondents thought it was ?Very Important? for SWAT officers to understand the basics of self-aid and buddy care and to carry an IFAK, while only 71% of respondents indicated that team members actually carried an IFAK. In addition, 67% indicated that tourniquets were part of the IFAK, and 91% of surveyed team leaders thought it was ?Very Important? for teams to have a trained medic available onsite at callouts or high-risk warrant searches. Also, 59% of teams used an organic TEMS element. The majority of SWAT team leaders recognize the benefit of basic Operator medical training and the importance of a TEMS program. Despite near 100% endorsement by unit-level leadership, a significant proportion of teams are lacking one of the key components including Operator IFAKs and/or tourniquets. Tactical team leaders, administrators, and providers should continue to promote adequate Operator training and equipment as well as formal TEMS support. 2013.

  8. Simulation and analysis of the effect of ungrounded rectangular loop distributed parameters on TEM response

    Science.gov (United States)

    Shi, Zongyang; Liu, Lihua; Xiao, Pan; Geng, Zhi; Liu, Fubo; Fang, Guangyou

    2018-02-01

    An ungrounded loop in the shallow subsurface transient electromagnetic surveys has been studied as the transmission line model for early turn-off stage, which can accurately explicate the early turn-off current waveform inconsistency along the loop. In this paper, the Gauss-Legendre numerical integration method is proposed for the first time to simulate and analyze the transient electromagnetic (TEM) response considering the different early turn-off current waveforms along the loop. During the simulation, these integral node positions along the loop are firstly determined by solving these zero points of Legendre polynomial, then the turn-off current of each node position is simulated by using the transfer function of the transmission line. Finally, the total TEM response is calculated by using the Gauss-Legendre integral formula. In addition, the comparison and analysis between the results affected by the distributed parameters and that generated by lumped parameters are presented. It is found that the TEM responses agree well with each other after current is thoroughly switched off, while the transient responses in turn-off stage are completely different. It means that the position dependence of the early turn-off current should be introduced into the forward model during the early response data interpretation of the shallow TEM detection of the ungrounded loop. Furthermore, the TEM response simulations at four geometric symmetry points are made. It shows that early responses of different geometric symmetry points are also inconsistent. The research on the influence of turn-off current position dependence on the early response of geometric symmetry point is of great significance to guide the layout of the survey lines and the transmitter location.

  9. Magnetic force microscopy of atherosclerotic plaque

    National Research Council Canada - National Science Library

    T A Alexeeva; S V Gorobets; O Yu Gorobets; I V Demianenko; O M Lazarenko

    2014-01-01

    In this work by methods of scanning probe microscopy, namely by atomic force microscopy and magnetic force microscopy the fragments of atherosclerotic plaque section of different nature were investigated...

  10. Field Emission Gun Scanning Electron (FEGSEM) and Transmission Electron (TEM) Microscopy of Phyllosilicates in Martian Meteorites ALH84001, Nakhla, and Shergotty

    Science.gov (United States)

    Thomas-Keprta, Kathie L.; Wentworth, Susan J.; McKay, David S.; Gibson, Everett K.

    2000-01-01

    Here we document the occurrence of phyllosilicates and alteration phases in three martian meteorites, suggest formation conditions required for phyllosilicate formation and speculate on the extent of fluid:rock interactions during the past history of Mars.

  11. Benchtop Transmission Electron Microscope (TEM) with Electron Diffraction (ED) and Scanning Electron Microscopy (SEM) Capabilities for Analysis of InorganicSolution-Processed Flexible Solar Cells

    Science.gov (United States)

    2015-04-30

    nanostructured scaffolds for catalysis in biofuels and other applications. The nanospheres, with particles sizes in the submicron to micron size,  Figure 2.a...distribution which is the information needed by researchers to validate further the packing capabilities in reactors that are tested for biofuels...Science and Catalysis 2008, 170B, 1827-1835.   Radu, Daniela R. Final Report 64755ELREP 3

  12. Light microscopy - Methods and protocols

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2011-11-01

    Full Text Available The first part of the book (six chapters is devoted to some selected applications of bright-field microscopy while the second part (eight chapters to some fluorescence microscopy studies. Both animal and plant biology investigations are presented covering multiple fields like immunology, cell signaling, cancer biology and, surprisingly to me, ecology. This chapter is titled: Light microscopy in aquatic ecology: Methods for plankton communities studies and it is due to Maria Carolina S. Soares and colleagues from the Laboratory of Aquatic Ecology, Dept. of Biology, Federal University of Juiz de Fora (Brazil. Here they present methods to quantify the different component of planktonic communities in a step-by-step manner so that virus, bacteria, algae and animals pertaining to different taxa can be recognized and the contribution they made to the plankton composition evaluated. It descends that even how the plankton composition is changing due to environmental variations can be accurately determined....

  13. Correlative fluorescence and electron microscopy.

    Science.gov (United States)

    Schirra, Randall T; Zhang, Peijun

    2014-10-01

    Correlative fluorescence and electron microscopy (CFEM) is a multimodal technique that combines dynamic and localization information from fluorescence methods with ultrastructural data from electron microscopy, to give new information about how cellular components change relative to the spatiotemporal dynamics within their environment. In this review, we will discuss some of the basic techniques and tools of the trade for utilizing this attractive research method, which is becoming a very powerful tool for biology labs. The information obtained from correlative methods has proven to be invaluable in creating consensus between the two types of microscopy, extending the capability of each, and cutting the time and expense associated with using each method separately for comparative analysis. The realization of the advantages of these methods in cell biology has led to rapid improvement in the protocols and has ushered in a new generation of instruments to reach the next level of correlation--integration. Copyright © 2014 John Wiley & Sons, Inc.

  14. Structured illumination microscopy and correlative microscopy to study autophagy.

    Science.gov (United States)

    Ligeon, Laure-Anne; Barois, Nicolas; Werkmeister, Elisabeth; Bongiovanni, Antonino; Lafont, Frank

    2015-03-01

    Autophagy is a predominant eukaryotic mechanism for the engulfment of "portions" of cytoplasm allowing their degradation to recycle metabolites. The autophagy is ubiquitous among the life kingdom revealing the importance of this pathway that appears more complex than previously thought. Several reviews have already addressed how to monitor this pathway and have highlighted the existence of new routes such as the LC3-associated phagocytosis (LAP) and the non-canonical autophagy. The principal difference between autophagosomes and LAP vacuoles is that the former has two limiting membranes positives for LC3 whereas the latter has one. Herein, we propose to emphasize the use of correlative light electron microscopy (CLEM) to answer some autophagy's related questions. The structured illumination microscopy (SIM) relatively easy to implement allows to better observe the Atg proteins recruitment and localization during the autophagy process. While LC3 recruitment is performed using light microscopy the ultrastructural morphological analysis of LC3-vacuoles is ascertained by electron microscopy. Hence, these combined and correlated approaches allow to tackle the LAP vs. autophagosome issue. Copyright © 2015. Published by Elsevier Inc.

  15. A FIB/TEM study of butterfly crack formation and white etching area (WEA) microstructural changes under rolling contact fatigue in 100Cr6 bearing steel

    Energy Technology Data Exchange (ETDEWEB)

    Evans, M.-H., E-mail: martin.evans@soton.ac.uk [National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, SO17 1BJ (United Kingdom); Walker, J.C.; Ma, C.; Wang, L.; Wood, R.J.K. [National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, SO17 1BJ (United Kingdom)

    2013-05-15

    Butterflies are microscopic damage features forming at subsurface material imperfections induced during rolling contact fatigue (RCF) in rolling element bearings. Butterflies can lead to degradation of the load bearing capacity of the material by their associated cracks causing premature spalling failures. Recently, butterfly formation has been cited to be related to a premature failure mode in wind turbine gearbox bearings; white structure flaking (WSF). Butterflies consist of cracks with surrounding microstructural change called ‘white etching area’ (WEA) forming wings that revolve around their initiators. The formation mechanisms of butterflies in bearing steels have been studied over the last 50 years, but are still not fully understood. This paper presents a detailed microstructural analysis of a butterfly that has initiated from a void in standard 100Cr6 bearing steel under rolling contact fatigue on a laboratory two-roller test rig under transient operating conditions. Analysis was conducted using focused ion beam (FIB) tomography, 3D reconstruction and transmission electron microscopy (STEM/TEM) methods. FIB tomography revealed an extensive presence of voids/cavities immediately adjacent to the main crack on the non-WEA side and at the crack tip. This provides evidence for a void/cavity coalescence mechanism for the butterfly cracks formation. Spherical M{sub 3}C carbide deformation and dissolution as part of the microstructural change in WEA were observed in both FIB and STEM/TEM analyses, where TEM analyses also revealed the formation of superfine nano-grains (3–15 nm diameter) intersecting a dissolving spherical M{sub 3}C carbide. This is evidence of the early formation of nano-grains associated with the WEA formation mechanism.

  16. Fundamental insight in soot oxidation over a Ag/Co3O4 catalyst by means of Environmental TEM

    DEFF Research Database (Denmark)

    Gardini, Diego; Christiansen, J. M.; Jensen, Anker Degn

    locally and globally. Removal of these particles from the exhaust gas is normally carried out by filtration through a ceramic filter. A major disadvantage of this technique is the need for periodic regenerations involving temperature increases in order to oxidize the collected soot. In an effort......A novel Ag/Co3O4 catalyst for low-temperature soot oxidation has been studied by means of environmental TEM in order to get fundamental insight in the oxidation mechanism. Soot particles generated in diesel engines are responsible for respiratory diseases, lung cancer and affect the climate both...... to minimize the filter regeneration temperature – ideally down to the normal temperature of the exhaust gas - a new catalyst for soot oxidation consisting of Ag nanoparticles supported on Co3O4 has been synthesized using flame spray pyrolysis and characterized using electron microscopy and X-Ray diffraction...

  17. Multiphoton Microscopy for Ophthalmic Imaging

    Directory of Open Access Journals (Sweden)

    Emily A. Gibson

    2011-01-01

    Full Text Available We review multiphoton microscopy (MPM including two-photon autofluorescence (2PAF, second harmonic generation (SHG, third harmonic generation (THG, fluorescence lifetime (FLIM, and coherent anti-Stokes Raman Scattering (CARS with relevance to clinical applications in ophthalmology. The different imaging modalities are discussed highlighting the particular strength that each has for functional tissue imaging. MPM is compared with current clinical ophthalmological imaging techniques such as reflectance confocal microscopy, optical coherence tomography, and fluorescence imaging. In addition, we discuss the future prospects for MPM in disease detection and clinical monitoring of disease progression, understanding fundamental disease mechanisms, and real-time monitoring of drug delivery.

  18. Magnetic Force Microscopy in Liquids.

    Science.gov (United States)

    Ares, Pablo; Jaafar, Miriam; Gil, Adriana; Gómez-Herrero, Julio; Asenjo, Agustina

    2015-09-01

    In this work, the use of magnetic force microscopy (MFM) to acquire images of magnetic nanostructures in liquid environments is presented. Optimization of the MFM signal acquisition in liquid media is performed and it is applied to characterize the magnetic signal of magnetite nanoparticles. The ability for detecting magnetic nanostructures along with the well-known capabilities of atomic force microscopy in liquids suggests potential applications in fields such as nanomedicine, nanobiotechnology, or nanocatalysis. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A study in the computation time required for the inclusion of strain field effects in Bloch-wave simulations of TEM diffraction contrast images

    Energy Technology Data Exchange (ETDEWEB)

    Dulong, B.J. [Department of Physics, Acadia University, Wolfville, N.S., B4P 2R6 (Canada); Haynes, R.D. [Department of Mathematics and Statistics, Acadia University, Wolfville, N.S., B4P 2R6 (Canada); Robertson, M.D. [Department of Physics, Acadia University, Wolfville, N.S., B4P 2R6 (Canada)], E-mail: michael.robertson@acadiau.ca

    2008-04-15

    As transmission electron microscopy (TEM) imaging techniques continue to become more quantitative, interpretation of the experimental images demands that accurate image simulations be computed incorporating all important aspects of the image including: compositional, crystallographic and microscope effects, as well as contrast due to strain fields arising from stresses created by lattice misfit or defects. Incorporation of the effects of strain fields in the simulation of diffraction-contrast TEM images in the Bloch-wave formalism requires the integration of a system of first-order differential equations in order to modify the excitation amplitudes and produce contrast in the image. This integration is computationally demanding with the time for integration scaling as the cube of the number of beams included in the calculation. In order to investigate the computational requirements of the integration, a variety of numerical integration packages were evaluated with respect to timing and accuracy in the simulation of quantum dot, spherical inclusion and screw dislocation images. It was determined that a class of Adams-multistep methods can provide a decrease in computation time ranging from 2 to 4 as compared to the standard Runge-Kutta 4(5) approach depending on the simulation conditions.

  20. A study in the computation time required for the inclusion of strain field effects in Bloch-wave simulations of TEM diffraction contrast images.

    Science.gov (United States)

    Dulong, B J; Haynes, R D; Robertson, M D

    2008-04-01

    As transmission electron microscopy (TEM) imaging techniques continue to become more quantitative, interpretation of the experimental images demands that accurate image simulations be computed incorporating all important aspects of the image including: compositional, crystallographic and microscope effects, as well as contrast due to strain fields arising from stresses created by lattice misfit or defects. Incorporation of the effects of strain fields in the simulation of diffraction-contrast TEM images in the Bloch-wave formalism requires the integration of a system of first-order differential equations in order to modify the excitation amplitudes and produce contrast in the image. This integration is computationally demanding with the time for integration scaling as the cube of the number of beams included in the calculation. In order to investigate the computational requirements of the integration, a variety of numerical integration packages were evaluated with respect to timing and accuracy in the simulation of quantum dot, spherical inclusion and screw dislocation images. It was determined that a class of Adams-multistep methods can provide a decrease in computation time ranging from 2 to 4 as compared to the standard Runge-Kutta 4(5) approach depending on the simulation conditions.

  1. Application of TEM and XPS in the interpretation of the kinetics of deuterium evolution from ultrathin TiD(y)/Pd films evaporated on quartz.

    Science.gov (United States)

    Lisowski, W; Keim, E G

    2009-04-01

    The kinetics of thermal evolution of deuterium from ultrathin TiD(y)/Pd bilayer films has been studied by means of thermal desorption mass spectrometry (TDMS). Using a combination of transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy, we made a study of the complex structural and chemical transformations of the TiD(y)/Pd film as a result of TDMS-induced evolution of deuterium and simultaneous annealing of this film. Both preparation and TDMS processing of the TiD(y)/Pd bilayer films were performed in situ under UHV conditions. It was found that the high-temperature TDMS processing of an ultrathin TiD(y)/Pd film, which was carried out in a relatively short time, leads to a significant film structure transformation. Energy-filtered TEM mapping of cross-section images and EDX analysis revealed extensive interdiffusion of Ti and Pd within the Ti-Pd bi-layer film. This process leads to a progressive change in chemical composition within the surface and subsurface area of the film during the TDMS processing. As the temperature of TDMS heating increases, segregation of Ti at the Pd top layer surface becomes significant. As a result, the kinetics of deuterium desorption is progressively changed during TDMS; at lower temperatures, the kinetics is limited by recombinative processes at the Pd surface, at temperatures beyond 500 K, it becomes dominated by interdiffusion of Ti into the Pd surface.

  2. Resistive switching mechanism in the one diode-one resistor memory based on p+-Si/n-ZnO heterostructure revealed by in-situ TEM.

    Science.gov (United States)

    Zhang, Lei; Zhu, Liang; Li, Xiaomei; Xu, Zhi; Wang, Wenlong; Bai, Xuedong

    2017-03-21

    One diode-one resistor (1D1R) memory is an effective architecture to suppress the crosstalk interference, realizing the crossbar network integration of resistive random access memory (RRAM). Herein, we designed a p + -Si/n-ZnO heterostructure with 1D1R function. Compared with the conventional multilayer 1D1R devices, the structure and fabrication technique can be largely simplified. The real-time imaging of formation/rupture process of conductive filament (CF) process demonstrated the RS mechanism by in-situ transmission electron microscopy (TEM). Meanwhile, we observed that the formed CF is only confined to the outside of depletion region of Si/ZnO pn junction, and the formation of CF does not degrade the diode performance, which allows the coexistence of RS and rectifying behaviors, revealing the 1D1R switching model. Furthermore, it has been confirmed that the CF is consisting of the oxygen vacancy by in-situ TEM characterization.

  3. Direct In-situ TEM Observation Of Modification Of Oxidation By The Injected Vacancies For Ni-4Al Alloy Using A Microfabricated Nanopost

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chong M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schreiber, Daniel K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Olszta, Matthew J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Baer, Donald R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bruemmer, Stephen M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-17

    Vacancy injection and selective oxidation of one specie in bimetallic alloy at high temperature is a well-known phenomenon. However, detailed understanding of the behavior of the injected vacancies and consequently their behavior and effect on oxidation remains elusive. The current research examines the oxidation of high-purity Ni doped with 4.1 at% Al using in-situ transmission electron microscopy (TEM). Experiments are performed on nanoposts fabricated from solution-annealed bulk material that are essentially single crystal samples. Initial oxidation is observed to occur by multi-site oxide nucleation, formation of an oxide shell followed by cavity nucleation and growth at the metal/oxide interface. One of the most interesting in-situ TEM observations is the formation of a cavity that leads to the faceting of the metal on (111) surface and subsequent oxidation occurring by an atomic ledge migration mechanism on the faceted metal surface. Further, it is directly observed that metal atoms diffuse through the oxide layer to combine with oxygen at the outer surface of the oxide. The present work indicates that injection of vacancies and formation of cavity will lead to a situation where the oxidation rate is essentially controlled by the low surface energy plane of the metal, rather than by the initial terminating plane at the metal surface exposed to the oxidizing environment.

  4. The Cell Surface Structure of Tumor Endothelial Marker 8 (TEM8) is Regulated by the Actin Cytoskeleton

    OpenAIRE

    Yang, Mi Young; Chaudhary, Amit; Seaman, Steven; Dunty, Jill; Stevens, Janine; Elzarrad, Mohammed K.; Frankel, Arthur E.; St. Croix, Brad

    2010-01-01

    Tumor Endothelial Marker 8 (TEM8) is an integrin-like cell surface protein upregulated on tumor blood vessels and a potential vascular target for cancer therapy. Here, we found that the ability of an anti-TEM8 antibody, clone SB5, to recognize the extracellular domain of TEM8 on the cell surface depends on other host-cell factors. By taking advantage of SB5’s ability to distinguish different forms of cell-surface TEM8, we identified alpha-smooth muscle actin and transgelin, an actin binding p...

  5. Cryo-FE-SEM & TEM immuno-techniques reveal new details for understanding white-rot decay of lignocellulose.

    Science.gov (United States)

    Daniel, Geoffrey; Volc, Jindrich; Niku-Paavola, Marja-Leena

    2004-01-01

    High-resolution Cryo-Field Emission Scanning Electron Microscopy (HR-Cryo-FE-SEM) and immuno-cytochemistry were used to reveal novel details on the morphological events and spatial distribution of oxidoreductive enzymes during the degradation of birch wood by the white-rot fungi Phlebia radiata and mutant strain P radiata Cel 26. Cryo-observations of fractured fibres showed degradation across the cell wall by P. radiata (wild) to progress by delamination and removal of concentric orientated aggregates from the secondary S2 cell wall. Decay by P radiata Cel 26 progressed by removal of materials (lignin and hemicelluloses) between the aggregates (primarily cellulose) that remained even after advanced decay. With both decay patterns, extracellular slime materials were present uniting lumina hyphae with the attacked fibre wall. The extracellular slime material had two morphological forms: viz a fibrillar (often tripartite) and a 'gel-form', the former found in discrete bands progressing across the lumen onto the fibre wall. Using TEM immunocytochemistry, laccase, manganese peroxidase (MnP) and diarylpropane enzymes were localized in the periplasmic space of luminal hyphae, in association with the cell membrane, periplasmic vesicles and fungal cell wall. Extracellularly, the three enzymes were found associated with the slime and tripartite membranes and with the birch cell walls at all stages of attack through to middle lamella corner decay. Enzyme distribution was correlated with morphological changes in cell wall structure. The association of extracellular slime with these enzymes and sites of decay strongly suggests a major role for this matrix in fibre cell wall decomposition.

  6. Determining the thickness of atomically thin MoS{sub 2} and WS{sub 2} in the TEM

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ryan J.; Odlyzko, Michael L.; Mkhoyan, K. Andre, E-mail: mkhoyan@umn.edu

    2014-12-15

    Multislice simulations were used to analyze the reliability of annular dark field scanning transmission electron microscopy (ADF-STEM) imaging and selected-area electron diffraction (SAED) for determining the thicknesses of MoS{sub 2} and WS{sub 2} specimens in the aberration-corrected TEM. Samples of 1 to 4 layers in thickness for both 2H and 1T polymorphs were studied and tilts up to 500 mrad off of the [0001] zone axis were considered. All thicknesses including the monolayer showed distortions and intensity variations in their ADF-STEM images and SAED patterns as a result of tilt. Both techniques proved to be applicable to distinguish monolayers from multilayers using tilt. Without tilt, neither technique allows unambiguous thickness determination solely by comparing relative intensities of atomic columns in ADF-STEM images or diffraction patterns oriented along at [0001] zone axis, with the exception of monolayer 2H WS{sub 2}. However, differentiation is possible using absolute intensities in ADF-STEM images. The analysis of ADF-STEM images and SAED patterns also allows identification of the 2H and 1T polymorphs of MoS{sub 2} and WS{sub 2}. - Highlights: • We performed multislice ADF-STEM image and SAED pattern simulations of MoS{sub 2} and WS{sub 2}. • We analyzed intensity variations in the image and patterns of tilted samples. • We determined ADF-STEM and SAED can be used to distinguish thickness up to 4 layers. • Both techniques can also be used to distinguish 2H and 1T polymorphs.

  7. Sintering of oxide-supported Pt and Pd nanoparticles in air studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose

    at elevated temperatures. The time-resolved TEM images are presented and these offer direct insight into the fundamental dynamics of the sintering process at the nano-scale. For Pt, Pd and bimetallic Pt-Pd nanoparticles it is shown that the sintering process is governed by the Ostwald ripening mechanism...... in an oxidizing environment. The observations compare well with predictions from mean-field kinetic models for ripening, but deviations are revealed for the timeevolution for the individual nanoparticles. A better description of the individual nanoparticle ripening is obtained by kinetic models that include local...... correlations between neighbouring nanoparticles in the atom-exchange process. The sintering process was also presented statistically by particle size distributions extracted from the TEM images. The statistical data agreed only partly with the mean-field kinetic models for ripening, but the deviations could...

  8. Customizable in situ TEM devices fabricated in freestanding membranes by focused ion beam milling

    DEFF Research Database (Denmark)

    Lei, Anders; Petersen, Dirch Hjorth; Booth, Tim

    2010-01-01

    Nano- and microelectromechanical structures for in situ operation in a transmission electron microscope (TEM) were fabricated with a turnaround time of 20 min and a resolution better than 100 nm. The structures are defined by focused ion beam (FIB) milling in 135 nm thin membranes of single....... The membrane structures provide a simple way to design electron-transparent nanodevices with high local temperature gradients within the field of view of the TEM, allowing detailed studies of surface diffusion processes. We show two examples of heat-induced coarsening of gold on a narrow freestanding bridge......, and that current annealing recrystallizes the structure, causing the electrical properties to partly recover to the pristine bulk resistivity. In situ imaging of the annealing process revealed both continuous and abrupt changes in the crystal structure, accompanied by instant changes of the electrical conductivity...

  9. Determination of crystallographic and macroscopic orientation of planar structures in TEM

    DEFF Research Database (Denmark)

    Huang, X.; Liu, Q.

    1998-01-01

    With the aid of a double-tilt holder in a transmission electron microscope (TEM), simple methods are described for determination of the crystallographic orientation of a planar structure and for calculation of the macroscopic orientation of the planar structure. The correlation between a planar...... structure and a crystallographic plane can be found by comparing the differences in their trace directions on the projection plane and inclination angles with respect to that plane. The angles between the traces of planar structures and the sample axis measured from the TEM micrographs, which have been...... taken at tilted positions, can be transformed to the real macroscopic orientation of the planar structures with estimated error of about +/- 2 degrees. (C) 1998 Elsevier Science B.V. All rights reserved....

  10. Nanofluidic chip for liquid TEM cell fabricated by parylene and silicon nitride direct bonding

    Science.gov (United States)

    Jang, Heejun; Kang, Il-Suk; Kim, Jihye; Kim, Jonghyun; Cha, Yun Jeong; Yoon, Dong Ki; Lee, Wonhee

    2017-09-01

    Despite the importance of nanofluidic transmission electron microscope (TEM) chips, a simple fabrication method has yet to be developed due to the difficulty of wafer bonding techniques using a nanoscale thick bonding layer. We present a simple and robust wafer scale bonding technique using parylene as a bonding layer. A nanoscale thick parylene layer was deposited on a silicon nitride (SiN) wafer and patterned to construct nanofluidic channels. The patterned parylene layer was directly bonded to another SiN wafer by thermal surface activation and bonding, with a bonding strength of ˜3 MPa. Fourier transform infrared spectroscopy showed that carbon-oxygen bonds were generated by thermal activation. We demonstrated TEM imaging of gold nanoparticles suspended in liquid using the fabricated nanofluidic chip.

  11. Microchip systems for imaging liquid and high temperature processes in TEM & SEM

    DEFF Research Database (Denmark)

    Jensen, Eric; Canepa, Silvia; Møller-Nilsen, Rolf Erling Robberstad

    2014-01-01

    measurementson high temperature fuel cell systems. For imaging processes in liquids, our SEM system enables imaging on-chip microelectrodes andusing standard built-in reference electrodes [2]. To get higher resolution in TEM, we have createda monolithic chip system with suspended microfabricated channels [3......]. Both systems will allowhigh resolution imaging of heterogeneous electrochemical processes such as those in batteries.Based on the suspended microfluidic channels, we are also developing microchips that enableultrafast freezing of processes in liquids....

  12. Mode basis method for spherical TEM-transmission lines and antennas

    OpenAIRE

    Butrym, Aleksander Yu.; Kochetov, Bogdan A.

    2007-01-01

    Mode basis method in spherical coordinate system is considered. Compared to the previous works in this field the method is generalized to take into consideration T-modes in conical lines and more general medium inhomogeneity that contains both radial and angular dependencies. A biconical and alike antennas (bow-tie, blade antenna, V-antenna, TEM-horn, etc.) can be rigorously analyzed with the proposed method.

  13. Thermal stress induced voids in nanoscale copper interconnects by in-situ TEM heating

    Science.gov (United States)

    An, Jin Ho

    Stress induced void formation in Cu interconnects, due to thermal stresses generated during the processing of semiconductors, is an increasing reliability issue in the semiconductor industry as Cu interconnects are being downscaled to follow the demand for faster chip speed. In this work, 1.8 micron and 180 nm wide Cu interconnects, fabricated by Freescale Semiconductors, were subjected to thermal cycles, in-situ in the TEM, to investigate the stress relaxation mechanisms as a function of interconnect linewidth. The experiments show that the 1.8 micron Cu interconnect lines relax the thermal stresses through dislocation nucleation and motion while the Cu interconnect 180 nm lines exhibit void formation. Void formation in 180 nm lines occurs predominantly at triple junctions where the Ta diffusion barrier meets a Cu grain boundary. In order to understand void formation in 180 nm lines, the grain orientation and local stresses are determined. In particular, Nanobeam Diffraction (NBD) in the TEM is used to obtain the diffraction pattern of each grain, from which the crystal orientation is evaluated by the ACT (Automated Crystallography for TEM) software. In addition, 2D Finite Element Method (FEM) simulations are performed using the Object Oriented Finite Modeling (OOF2) software to correlate grain orientation with local stresses, and consequently void formation. According to the experimental and simulation results obtained, void formation in 180nm Cu interconnects does not seem to be solely dependent on local stresses, but a combination of diffusion paths available, stress gradients and possibly the presence of defects. In addition, based on the in-situ TEM observations, void growth seems to occur through grain boundary and/or interfacial diffusion. However, in-situ STEM observations of fully opened voids post-failure show pileup of material at the Cu grain surfaces. This means that surface or interface diffusion is also very active during void growth in the presence

  14. Atomic force microscopy applied to the quantification of nano-precipitates in thermo-mechanically treated microalloyed steels

    Energy Technology Data Exchange (ETDEWEB)

    Renteria-Borja, Luciano [Instituto Tecnologico de Morelia, Av. Tecnologico No. 1500, Lomas de Santiaguito, 58120 Morelia (Mexico); Hurtado-Delgado, Eduardo, E-mail: hurtado@itmorelia.edu.mx [Instituto Tecnologico de Morelia, Av. Tecnologico No. 1500, Lomas de Santiaguito, 58120 Morelia (Mexico); Garnica-Gonzalez, Pedro [Instituto Tecnologico de Morelia, Av. Tecnologico No. 1500, Lomas de Santiaguito, 58120 Morelia (Mexico); Dominguez-Lopez, Ivan; Garcia-Garcia, Adrian Luis [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN Unidad Queretaro, Cerro Blanco No. 141, Colinas del Cimatario, 76090 Queretaro (Mexico)

    2012-07-15

    Quantification of nanometer-size precipitates in microalloyed steels has been traditionally performed using transmission electron microscopy (TEM), in spite of its complicated sample preparation procedures, prone to preparation errors and sample perturbation. In contrast to TEM procedures, atomic force microscopy (AFM) is performed on the as-prepared specimen, with sample preparation requirements similar to those for optical microscopy (OM), rendering three-dimensional representations of the sample surface with vertical resolution of a fraction of a nanometer. In AFM, contrast mechanisms are directly related to surface properties such as topography, adhesion, and stiffness, among others. Chemical etching was performed using 0.5% nital, at time intervals between 4 and 20 s, in 4 s steps, until reaching the desired surface finish. For the present application, an average surface-roughness peak-height below 200 nm was sought. Quantification results of nanometric precipitates were obtained from the statistical analysis of AFM images of the microstructure developed by microalloyed Nb and V-Mo steels. Topography and phase contrast AFM images were used for quantification. The results obtained using AFM are consistent with similar TEM reports. - Highlights: Black-Right-Pointing-Pointer We quantified nanometric precipitates in Nb and V-Mo microalloyed steels using AFM. Black-Right-Pointing-Pointer Microstructures of the thermo-mechanically treated microalloyed steels were used. Black-Right-Pointing-Pointer Topography and phase contrast AFM images were used for quantification. Black-Right-Pointing-Pointer AFM results are comparable with traditionally obtained TEM measurements.

  15. Quantitative super-resolution microscopy

    NARCIS (Netherlands)

    Harkes, Rolf

    2016-01-01

    Super-Resolution Microscopy is an optical fluorescence technique. In this thesis we focus on single molecule super-resolution, where the position of single molecules is determined. Typically these molecules can be localized with a 10 to 30nm precision. This technique is applied in four different

  16. Mechanics in Steels through Microscopy

    NARCIS (Netherlands)

    Zandbergen, H.W.; Tirumalasetty, G.K.

    The goal of the study consolidated in this thesis is to understand the mechanics in steels using microscopy. In particular, the mechanical response of Transformation Induced Plasticity (TRIP) steels is correlated with their microstructures. Chapter 1 introduces the current state of the art of TRIP

  17. Color-televised medical microscopy

    Science.gov (United States)

    Heath, M. A.; Peck, J. C.

    1968-01-01

    Color television microscopy used at laboratory range magnifications, reproduces a slide image with sufficient fidelity for medical laboratory and instructional use. The system is used for instant pathological reporting between operating room and remotely located pathologist viewing a biopsy through this medium.

  18. 3D -Ray Diffraction Microscopy

    DEFF Research Database (Denmark)

    Poulsen, Henning Friis; Schmidt, Søren; Juul Jensen, Dorte

    2014-01-01

    Three-dimensional X-ray diffraction (3DXRD) microscopy is a fast and non-destructive structural characterization technique aimed at the study of individual crystalline elements (grains or subgrains) within mm-sized polycrystalline specimens. It is based on two principles: the use of highly...

  19. Vacuum scanning capillary photoemission microscopy

    DEFF Research Database (Denmark)

    Aseyev, S.A.; Cherkun, A P; Mironov, B N

    2017-01-01

    We demonstrate the use of a conical capillary in a scanning probe microscopy for surface analysis. The probe can measure photoemission from a substrate by transmitting photoelectrons along the capillary as a function of probe position. The technique is demonstrated on a model substrate consisting...

  20. Advanced Microscopy of Microbial Cells

    DEFF Research Database (Denmark)

    Haagensen, Janus Anders Juul; Regenberg, Birgitte; Sternberg, Claus

    2011-01-01

    Growing awareness of heterogeneity in cells of microbial populations has emphasized the importance of advanced microscopy for visualization and understanding of the molecular mechanisms underlying cell-to-cell variation. In this review, we highlight some of the recent advances in confocal...... for visualization of variation between cells in phenotypic traits such as gene expression....

  1. High Resolution Scanning Ion Microscopy

    NARCIS (Netherlands)

    Castaldo, V.

    2011-01-01

    The structure of the thesis is the following. The first chapter is an introduction to scanning microscopy, where the path that led to the Focused Ion Beam (FIB) is described and the main differences between electrons and ion beams are highlighted. Chapter 2 is what is normally referred to (which I

  2. Filter-Dense Multicolor Microscopy.

    Directory of Open Access Journals (Sweden)

    Siavash Kijani

    Full Text Available Immunofluorescence microscopy is a unique method to reveal the spatial location of proteins in tissues and cells. By combining antibodies that are labeled with different fluorochromes, the location of several proteins can simultaneously be visualized in one sample. However, because of the risk of bleed-through signals between fluorochromes, standard multicolor microscopy is restricted to a maximum of four fluorescence channels, including one for nuclei staining. This is not always enough to address common scientific questions. In particular, the use of a rapidly increasing number of marker proteins to classify functionally distinct cell populations and diseased tissues emphasizes the need for more complex multistainings. Hence, multicolor microscopy should ideally offer more channels to meet the current needs in biomedical science. Here we present an enhanced multi-fluorescence setup, which we call Filter-Dense Multicolor Microscopy (FDMM. FDMM is based on condensed filter sets that are more specific for each fluorochrome and allow a more economic use of the light spectrum. FDMM allows at least six independent fluorescence channels and can be applied to any standard fluorescence microscope without changing any operative procedures for the user. In the present study, we demonstrate an FDMM setup of six channels that includes the most commonly used fluorochromes for histology. We show that the FDMM setup is specific and robust, and we apply the technique on typical biological questions that require more than four fluorescence microscope channels.

  3. Mechanics in Steels through Microscopy

    NARCIS (Netherlands)

    Tirumalasetty, G.K.

    2013-01-01

    The goal of the study consolidated in this thesis is to understand the mechanics in steels using microscopy. In particular, the mechanical response of Transformation Induced Plasticity (TRIP) steels is correlated with their microstructures. Chapter 1 introduces the current state of the art of TRIP

  4. Light Microscopy at Maximal Precision

    Science.gov (United States)

    Bierbaum, Matthew; Leahy, Brian D.; Alemi, Alexander A.; Cohen, Itai; Sethna, James P.

    2017-10-01

    Microscopy is the workhorse of the physical and life sciences, producing crisp images of everything from atoms to cells well beyond the capabilities of the human eye. However, the analysis of these images is frequently little more accurate than manual marking. Here, we revolutionize the analysis of microscopy images, extracting all the useful information theoretically contained in a complex microscope image. Using a generic, methodological approach, we extract the information by fitting experimental images with a detailed optical model of the microscope, a method we call parameter extraction from reconstructing images (PERI). As a proof of principle, we demonstrate this approach with a confocal image of colloidal spheres, improving measurements of particle positions and radii by 10-100 times over current methods and attaining the maximum possible accuracy. With this unprecedented accuracy, we measure nanometer-scale colloidal interactions in dense suspensions solely with light microscopy, a previously impossible feat. Our approach is generic and applicable to imaging methods from brightfield to electron microscopy, where we expect accuracies of 1 nm and 0.1 pm, respectively.

  5. Automated determination of size and morphology information from soot transmission electron microscope (TEM)-generated images

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng; Chan, Qing N., E-mail: qing.chan@unsw.edu.au; Zhang, Renlin; Kook, Sanghoon; Hawkes, Evatt R.; Yeoh, Guan H. [UNSW, School of Mechanical and Manufacturing Engineering (Australia); Medwell, Paul R. [The University of Adelaide, Centre for Energy Technology (Australia)

    2016-05-15

    The thermophoretic sampling of particulates from hot media, coupled with transmission electron microscope (TEM) imaging, is a combined approach that is widely used to derive morphological information. The identification and the measurement of the particulates, however, can be complex when the TEM images are of low contrast, noisy, and have non-uniform background signal level. The image processing method can also be challenging and time consuming, when the samples collected have large variability in shape and size, or have some degree of overlapping. In this work, a three-stage image processing sequence is presented to facilitate time-efficient automated identification and measurement of particulates from the TEM grids. The proposed processing sequence is first applied to soot samples that were thermophoretically sampled from a laminar non-premixed ethylene-air flame. The parameter values that are required to be set to facilitate the automated process are identified, and sensitivity of the results to these parameters is assessed. The same analysis process is also applied to soot samples that were acquired from an externally irradiated laminar non-premixed ethylene-air flame, which have different geometrical characteristics, to assess the morphological dependence of the proposed image processing sequence. Using the optimized parameter values, statistical assessments of the automated results reveal that the largest discrepancies that are associated with the estimated values of primary particle diameter, fractal dimension, and prefactor values of the aggregates for the tested cases, are approximately 3, 1, and 10 %, respectively, when compared with the manual measurements.

  6. Determination of the initial oxidation behavior of Zircaloy-4 by in-situ TEM

    Energy Technology Data Exchange (ETDEWEB)

    Harlow, Wayne; Ghassemi, Hessam; Taheri, Mitra L., E-mail: mtaheri@coe.drexel.edu

    2016-06-15

    The corrosion behavior of Zircaloy-4 (Zry-4), specifically by oxidation, is a problem of great importance as this material is critical for current nuclear reactor cladding. The early formation behavior and structure of the oxide layer during oxidation was studied using in-situ TEM techniques that allowed for Zry-4 to be monitored during corrosion. These environmental exposure experiments were coupled with precession electron diffraction to identify and quantify the phases present in the samples before and after the oxidation. Following short-term, high temperature oxidation, the dominant phase was revealed to be monoclinic ZrO{sub 2} in a columnar structure. These samples oxidized in-situ contained structures that correlated well with bulk Zry-4 subjected to autoclave treatment, which were used for comparison and validation of this technique. By using in-situ TEM the effect of microstructure features, such as grain boundaries, on oxidation behavior of an alloy can be studied. The technique presented herein holds the potential to be applied any alloy system to study these effects. - Highlights: • In-situ TEM was used to oxidize samples of Zircaloy-4. • Similar behavior was found in the in-situ oxidized and autoclave-oxidized samples. • Precession diffraction was used to characterize oxide phase and texture.

  7. Differential dependence on N-glycosylation of anthrax toxin receptors CMG2 and TEM8.

    Directory of Open Access Journals (Sweden)

    Sarah Friebe

    Full Text Available ANTXR 1 and 2, also known as TEM8 and CMG2, are two type I membrane proteins, which have been extensively studied for their role as anthrax toxin receptors, but with a still elusive physiological function. Here we have analyzed the importance of N-glycosylation on folding, trafficking and ligand binding of these closely related proteins. We find that TEM8 has a stringent dependence on N-glycosylation. The presence of at least one glycan on each of its two extracellular domains, the vWA and Ig-like domains, is indeed necessary for efficient trafficking to the cell surface. In the absence of any N-linked glycans, TEM8 fails to fold correctly and is recognized by the ER quality control machinery. Expression of N-glycosylation mutants reveals that CMG2 is less vulnerable to sugar loss. The absence of N-linked glycans in one of the extracellular domains indeed has little impact on folding, trafficking or receptor function of the wild type protein expressed in tissue culture cells. N-glycans do, however, seem required in primary fibroblasts from human patients. Here, the presence of N-linked sugars increases the tolerance to mutations in cmg2 causing the rare genetic disease Hyaline Fibromatosis Syndrome. It thus appears that CMG2 glycosylation provides a buffer towards genetic variation by promoting folding of the protein in the ER lumen.

  8. TEM heat transport and fluctuations in the HSX stellarator: experiments and comparison with gyrokinetic simulation

    Science.gov (United States)

    Smoniewski, J.; Faber, B. J.; Sánchez, E.; Calvo, I.; Pueschel, M. J.; Likin, K. M.; Deng, C. B.; Talmadge, J. N.

    2017-10-01

    The Helically Symmetric eXperiment (HSX) has demonstrated reduced neoclassical transport in the plasma core with quasi-symmetry [Lore Thesis 2010], while outside this region the electron thermal diffusivity is well above the neoclassical level, likely due to the Trapped Electron Mode (TEM) [Weir PoP 2015, Faber PoP 2015]. We compare gyrokinetic simulations of the TEM to experimental heat flux and density fluctuation measurements for two configurations: Quasi-Helical Symmetry (QHS) and broken symmetry (Mirror). Both experiment and simulation show that the heat flux for Mirror is larger than for QHS by about a factor of two. Initial interferometer measurements provide evidence that density-gradient-driven TEMs are driving turbulence. Calculations of the collisionless damping of zonal flows provide another perspective into the difference between geometries. Similar to other stellarators [Monreal PPCF 2016], the zonal flow residual goes to zero at long wavelengths in both configurations. Additionally, the very short time decay of the zonal flow due to neoclassical polarization is constant between configurations. However, the collisionless damping time is longer and the zonal flow oscillation frequency is smaller in QHS than Mirror, consistent with reduced radial particle drifts. Work supported by the US DOE under Grant DE-FG02-93ER54222.

  9. Characterization of strained semiconductor structures using transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oezdoel, Vasfi Burak

    2011-08-15

    Today's state-of-the-art semiconductor electronic devices utilize the charge transport within very small volumes of the active device regions. The structural, chemical and optical material properties in these small dimensions can critically affect the performance of these devices. The present thesis is focused on the nanometer scale characterization of the strain state in semiconductor structures using transmission electron microscopy (TEM). Although high-resolution TEM has shown to provide the required accuracy at the nanometer scale, optimization of imaging conditions is necessary for accurate strain measurements. An alternative HRTEM method based on strain mapping on complex-valued exit face wave functions is developed to reduce the artifacts arising from objective lens aberrations. However, a much larger field of view is crucial for mapping strain in the active regions of complex structures like latest generation metal-oxide-semiconductor field-effect transistors (MOSFETs). To overcome this, a complementary approach based on electron holography is proposed. The technique relies on the reconstruction of the phase shifts in the diffracted electron beams from a focal series of dark-field images using recently developed exit-face wave function reconstruction algorithm. Combining high spatial resolution, better than 1 nm, with a field of view of about 1 {mu}m in each dimension, simultaneous strain measurements on the array of MOSFETs are possible. Owing to the much lower electron doses used in holography experiments when compared to conventional quantitative methods, the proposed approach allows to map compositional distribution in electron beam sensitive materials such as InGaN heterostructures without alteration of the original morphology and chemical composition. Moreover, dark-field holography experiments can be performed on thicker specimens than the ones required for high-resolution TEM, which in turn reduces the thin foil relaxation. (orig.)

  10. In situ and operando transmission electron microscopy of catalytic materials

    DEFF Research Database (Denmark)

    Crozier, Peter A.; Hansen, Thomas Willum

    2015-01-01

    Catalytic nanomaterials play a major role in chemical conversions and energy transformations. Understanding how materials control and regulate surface reactions is a major objective for fundamental research on heterogeneous catalysts. In situ environmental transmission electron microscopy (ETEM......) is a powerful technique for revealing the atomic structures of materials at elevated temperatures in the presence of reactive gases. This approach can allow the structure-reactivity relations underlying catalyst functionality to be investigated. Thus far, ETEM has been limited by the absence of in situ...... measurements of gas-phase catalytic products. To overcome this deficiency, operando TEM techniques are being developed that combine atomic characterization with the simultaneous measurement of catalytic products. This article provides a short review of the current status and major developments...

  11. Turning Microscopy in the Medical Curriculum Digital

    DEFF Research Database (Denmark)

    Vainer, Ben; Mortensen, Niels Werner; Poulsen, Steen Seier

    2017-01-01

    an administrative, an economic, and a teaching perspective. This fully automatic digital microscopy system has been received positively by both teachers and students, and a decision was made to convert all courses involving microscopy to the virtual microscopy format. As a result, conventional analog microscopy...

  12. Electron microscopy by specimen design: application to strain measurements.

    Science.gov (United States)

    Cherkashin, Nikolay; Denneulin, Thibaud; Hÿtch, Martin J

    2017-09-29

    A bewildering number of techniques have been developed for transmission electron microscopy (TEM), involving the use of ever more complex combinations of lens configurations, apertures and detector geometries. In parallel, the developments in the field of ion beam instruments have modernized sample preparation and enabled the preparation of various types of materials. However, the desired final specimen geometry is always almost the same: a thin foil of uniform thickness. Here we will show that judicious design of specimen geometry can make all the difference and that experiments can be carried out on the most basic electron microscope and in the usual imaging modes. We propose two sample preparation methods that allow the formation of controlled moiré patterns for general monocrystalline structures in cross-section and at specific sites. We developed moiré image treatment algorithms using an absolute correction of projection lens distortions of a TEM that allows strain measurements and mapping with a nanometer resolution and 10-4 precision. Imaging and diffraction techniques in other fields may in turn benefit from this technique in perspective.

  13. Transmission electron microscopy in molecular structural biology: A historical survey.

    Science.gov (United States)

    Harris, J Robin

    2015-09-01

    In this personal, historic account of macromolecular transmission electron microscopy (TEM), published data from the 1940s through to recent times is surveyed, within the context of the remarkable progress that has been achieved during this time period. The evolution of present day molecular structural biology is described in relation to the associated biological disciplines. The contribution of numerous electron microscope pioneers to the development of the subject is discussed. The principal techniques for TEM specimen preparation, thin sectioning, metal shadowing, negative staining and plunge-freezing (vitrification) of thin aqueous samples are described, with a selection of published images to emphasise the virtues of each method. The development of digital image analysis and 3D reconstruction is described in detail as applied to electron crystallography and reconstructions from helical structures, 2D membrane crystals as well as single particle 3D reconstruction of icosahedral viruses and macromolecules. The on-going development of new software, algorithms and approaches is highlighted before specific examples of the historical progress of the structural biology of proteins and viruses are presented. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. TRANSMISSION ELECTRON MICROSCOPY STUDY OF HELIUM BEARING FUSION WELDS

    Energy Technology Data Exchange (ETDEWEB)

    Tosten, M; Michael Morgan, M

    2008-12-12

    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.

  15. Cryogenic transmission electron microscopy nanostructural study of shed microparticles.

    Directory of Open Access Journals (Sweden)

    Liron Issman

    Full Text Available 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.

  16. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    Directory of Open Access Journals (Sweden)

    Stephen A. Boppart

    2008-06-01

    Full Text Available Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT, utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR. In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

  17. Simultaneous Bright-Field and Dark-Field Scanning Transmission Electron Microscopy in Scanning Electron Microscopy: A New Approach for Analyzing Polymer System Morphology

    Science.gov (United States)

    Patel, Binay S.

    Scanning transmission electron microscopy in scanning electron microscopy (STEM-IN-SEM) is a convenient technique for polymer characterization. Utilizing the lower accelerating voltages, larger field of view and, exclusion of post-specimen projection lens in an SEM; STEM-IN-SEM has shown results comparable to transmission electron microscopy (TEM) observation of polymer morphology. Various specimen-holder geometries and detector arrangements have been used for bright field (BF) STEM-IN-SEM imaging. To further the characterization potential of STEM-IN-SEM a new specimen holder has been developed to facilitate simultaneous BF and dark field (DF) STEM-IN-SEM imaging. A new specimen holder and a new microscope configuration were designed for this new imaging technique. BF and DF signals were maximized for optimal STEM-IN-SEM imaging. BF signal intensities were found to be twice as large as DF signal intensities. BF and DF STEM-IN-SEM imaging spatial resolutions are limited to 1.8 nm and approximately 5 nm, respectively. Simultaneous BF & DF STEM-IN-SEM imaging is applicable to both industrial and academic research environments. Examples of commodity and engineering polymer morphology characterization are provided. Results are comparable to TEM observation and may serve as a suitable precursor to STEM characterization of polymer systems. Finally, future developments of various accessories for this technique are discussed.

  18. U-shaped Ladder TEM-Coil Structure with Truncated Sensitivity Profile in z-Direction for High Field MRI

    NARCIS (Netherlands)

    Leussler, C.; Wirtz, D.; Wuelbern, J.H.; Vernickel, P.; Forthmann, P.

    2012-01-01

    Conventional TEM-coils [1] come with a sensitivity profile and field-of view (FOV) that is largely extended in the z-direction comparedwith birdcage coils (BC) [2]. There is an analog situation when comparing TEM coil arrays [3] and degenerate birdcages (DBC) [4]. The excess z-FOV leads to safety

  19. Growth of Pd-Filled Carbon Nanotubes on the Tip of Scanning Probe Microscopy

    Directory of Open Access Journals (Sweden)

    Tomokazu Sakamoto

    2009-01-01

    Full Text Available We have synthesized Pd-filled carbon nanotubes (CNTs oriented perpendicular to Si substrates using a microwave plasma-enhanced chemical vapor deposition (MPECVD for the application of scanning probe microscopy (SPM tip. Prior to the CVD growth, Al thin film (10 nm was coated on the substrate as a buffer layer followed by depositing a 5∼40 nm-thick Pd film as a catalyst. The diameter and areal density of CNTs grown depend largely on the initial Pd thickness. Scanning electron microscopy (SEM and transmission electron microscopy (TEM images clearly show that Pd is successfully encapsulated into the CNTs, probably leading to higher conductivity. Using optimum growth conditions, Pd-filled CNTs are successfully grown on the apex of the conventional SPM cantilever.

  20. Microscopy studies on pronton exchange membrane fuel cell electrodes with different ionomer contents

    DEFF Research Database (Denmark)

    Ma, Shuang; Solterbeck, Claus Henning; Odgaard, Madeleine

    2009-01-01

    content in the catalyst layer. Transmission electron microscopy (TEM) was carried out on selective electrodes to provide additional information and confirmed with the AFM results. Cyclic voltammetry (CV) showed that the electrode containing 30 wt.% ionomer has maximum catalyst utilization.......Proton Exchange Membrane (PEM) fuel cell electrodes with different ionomer contents were studied with various microscopic techniques. The morphology and surface potential were examined by Atomic Force Microscopy (AFM) and Kelvin Probe Microscopy (KPM), respectively. The particulate nature...... in high ionomer content electrodes. The surface potential images showed distinct difference to the topography images. The overall grain size was seen to increase, the pore volume to decrease, the surface roughness to decrease, and the surface potential variation to increase with the increase of ionomer...

  1. Implementing atomic force microscopy (AFM) for studying kinetics of gold nanoparticle's growth

    DEFF Research Database (Denmark)

    Georgiev, P.; Bojinova, A.; Kostova, B.

    2013-01-01

    In a novel experimental approach Atomic Force Microscopy (AFM) was applied as a tool for studying the kinetics of gold nanoparticle growth. The gold nanoparticles were obtained by classical Turkevich citrate synthesis at two different temperatures. From the analysis of AFM images during the synth......In a novel experimental approach Atomic Force Microscopy (AFM) was applied as a tool for studying the kinetics of gold nanoparticle growth. The gold nanoparticles were obtained by classical Turkevich citrate synthesis at two different temperatures. From the analysis of AFM images during...... approach. We also compared AFM experimental data with Dynamic Light Scattering (DLS) and with Transmission Electron Microscopy (TEM) data. The experimental data from all the applied methods were fitted with two step Finke-Watzky kinetics model and the corresponding kinetics constants were obtained...

  2. QUANTITATIVE CONFOCAL LASER SCANNING MICROSCOPY

    Directory of Open Access Journals (Sweden)

    Merete Krog Raarup

    2011-05-01

    Full Text Available This paper discusses recent advances in confocal laser scanning microscopy (CLSM for imaging of 3D structure as well as quantitative characterization of biomolecular interactions and diffusion behaviour by means of one- and two-photon excitation. The use of CLSM for improved stereological length estimation in thick (up to 0.5 mm tissue is proposed. The techniques of FRET (Fluorescence Resonance Energy Transfer, FLIM (Fluorescence Lifetime Imaging Microscopy, FCS (Fluorescence Correlation Spectroscopy and FRAP (Fluorescence Recovery After Photobleaching are introduced and their applicability for quantitative imaging of biomolecular (co-localization and trafficking in live cells described. The advantage of two-photon versus one-photon excitation in relation to these techniques is discussed.

  3. Selective sensitivity in Kerr microscopy

    Science.gov (United States)

    Soldatov, I. V.; Schäfer, R.

    2017-07-01

    A new technique for contrast separation in wide-field magneto-optical Kerr microscopy is introduced. Utilizing the light from eight light emitting diodes, guided to the microscope by glass fibers and being switched synchronously with the camera exposure, domain images with orthogonal in-plane sensitivity can be displayed simultaneously at real-time, and images with pure in-plane or polar contrast can be obtained. The benefit of this new method of contrast separation is demonstrated for Permalloy films, a NdFeB sinter magnet, and a cobalt crystal. Moreover, the new technique is shown to strongly enhance the sensitivity of Kerr microscopy by eliminating parasitic contrast contributions occurring in conventional setups. A doubling of the in-plane domain contrast and a sensitivity to Kerr rotations as low as 0.6 mdeg is demonstrated.

  4. Advanced Methods in Fluorescence Microscopy

    Directory of Open Access Journals (Sweden)

    Luke Fritzky

    2013-01-01

    Full Text Available It requires a good deal of will power to resist hyperbole in considering the advances that have been achieved in fluorescence microscopy in the last 25 years. Our effort has been to survey the modalities of microscopic fluorescence imaging available to cell biologists and perhaps useful for diagnostic pathologists. The gamut extends from established confocal laser scanning through multiphoton and TIRF to the emerging technologies of super-resolution microscopy that breech the Abbé limit of resolution. Also considered are the recent innovations in structured and light sheet illumination, the use of FRET and molecular beacons that exploit specific characteristics of designer fluorescent proteins, fluorescence speckles, and second harmonic generation for native anisometric structures like collagen, microtubules and sarcomeres.

  5. All-optical photoacoustic microscopy

    Directory of Open Access Journals (Sweden)

    Sung-Liang Chen

    2015-12-01

    Full Text Available Three-dimensional photoacoustic microscopy (PAM has gained considerable attention within the biomedical imaging community during the past decade. Detecting laser-induced photoacoustic waves by optical sensing techniques facilitates the idea of all-optical PAM (AOPAM, which is of particular interest as it provides unique advantages for achieving high spatial resolution using miniaturized embodiments of the imaging system. The review presents the technology aspects of optical-sensing techniques for ultrasound detection, such as those based on optical resonators, as well as system developments of all-optical photoacoustic systems including PAM, photoacoustic endoscopy, and multi-modality microscopy. The progress of different AOPAM systems and their representative applications are summarized.

  6. A history of urine microscopy.

    Science.gov (United States)

    Cameron, J Stewart

    2015-11-01

    The naked-eye appearance of the urine must have been studied by shamans and healers since the Stone Age, and an elaborate interpretation of so-called Uroscopy began around 600 AD as a form of divination. A 1000 years later, the first primitive monocular and compound microscopes appeared in the Netherlands, and along with many other objects and liquids, urine was studied from around 1680 onwards as the enlightenment evolved. However, the crude early instruments did not permit fine study because of chromatic and linear/spherical blurring. Only after complex multi-glass lenses which avoided these problems had been made and used in the 1820s in London by Lister, and in Paris by Chevalier and Amici, could urinary microscopy become a practical, clinically useful tool in the 1830s. Clinical urinary microscopy was pioneered by Rayer and his pupils in Paris (especially Vigla), in the late 1830s, and spread to UK and Germany in the 1840s, with detailed descriptions and interpretations of cells and formed elements of the urinary sediment by Nasse, Henle, Robinson and Golding Bird. Classes were held, most notably by Donné in Paris. After another 50 years, optical microscopy had reached its apogee, with magnifications of over 1000 times obtainable free of aberration, using immersion techniques. Atlases of the urinary sediment were published in all major European countries and in the US. Polarised light and phase contrast was used also after 1900 to study urine, and by the early 20th century, photomicroscopy (pioneered by Donné and Daguerre 50 years previously, but then ignored) became usual for teaching and recording. In the 1940s electron microscopy began, followed by detection of specific proteins and cells using immunofluorescent antibodies. All this had been using handheld methodology. Around 1980, machine-assisted observations began, and have dominated progress since.

  7. Quantum state atomic force microscopy

    OpenAIRE

    Passian, Ali; Siopsis, George

    2017-01-01

    New classical modalities of atomic force microscopy continue to emerge to achieve higher spatial, spectral, and temporal resolution for nanometrology of materials. Here, we introduce the concept of a quantum mechanical modality that capitalizes on squeezed states of probe displacement. We show that such squeezing is enabled nanomechanically when the probe enters the van der Waals regime of interaction with a sample. The effect is studied in the non-contact mode, where we consider the paramete...

  8. Light Sheet Fluorescence Microscopy (LSFM)

    OpenAIRE

    Adams, Michael W.; Loftus, Andrew F.; Dunn, Sarah E.; Joens, Matthew S.; Fitzpatrick, James A. J.

    2015-01-01

    The development of confocal microscopy techniques introduced the ability to optically section fluorescent samples in the axial dimension, perpendicular to the image plane. These approaches, via the placement of a pinhole in the conjugate image plane, provided superior resolution in the axial (z) dimension resulting in nearly isotropic optical sections. However, increased axial resolution, via pinhole optics, comes at the cost of both speed and excitation efficiency. Light Sheet Fluorescent Mi...

  9. Functionalization of a nanostructured hydroxyapatite with copper(II) compounds as pesticide: in situ TEM and ESEM observations of treated Vitis vinifera L. leaves.

    Science.gov (United States)

    Battiston, Enrico; Salvatici, Maria C; Lavacchi, Alessandro; Gatti, Antonietta; Di Marco, Stefano; Mugnai, Laura

    2018-02-19

    The present study evaluates a biocompatible material for plant protection to reduce the amount of active substance applied. We used a synthetic hydroxyapatite (HA) that has been studied extensively due its bioactivity and biocompatibility. Aggregation between HA nanoparticles and four copper(II) compounds applied in Vitis vinifera L. leaves as pesticide was studied. Formulations were characterised by XRD, DLS, electron microscopy and applied in planta to verify the particle aggregation and efficiency in controlling the pathogen, Plasmopara viticola. XRD showed a different interaction between HA and the copper(II) compounds, DLS showed a granular distribution ranging out of the nanometer range and in all formulations, TEM and ESEM microscopy showed large aggregates which were partially nanostructured and were recognised as stable in their micrometric dimension. Such particles did not show phytotoxic effects after their application in planta. A formulation based on HA and the soluble copper(II) compound showed promising results in the control of the fungal pathogen, confirming the potential role of HA an as innovative delivery system of Cu(II) ions. The present work indicates the possibility to improve the biological activity of a bioactive substance by modifying its structure through an achievable formulation with a biocompatible material. This article is protected by copyright. All rights reserved.

  10. Cryo-electron microscopy and cryo-electron tomography of nanoparticles.

    Science.gov (United States)

    Stewart, Phoebe L

    2017-03-01

    Cryo-transmission electron microscopy (cryo-TEM or cryo-EM) and cryo-electron tomography (cryo-ET) offer robust and powerful ways to visualize nanoparticles. These techniques involve imaging of the sample in a frozen-hydrated state, allowing visualization of nanoparticles essentially as they exist in solution. Cryo-TEM grid preparation can be performed with the sample in aqueous solvents or in various organic and ionic solvents. Two-dimensional (2D) cryo-TEM provides a direct way to visualize the polydispersity within a nanoparticle preparation. Fourier transforms of cryo-TEM images can confirm the structural periodicity within a sample. While measurement of specimen parameters can be performed with 2D TEM images, determination of a three-dimensional (3D) structure often facilitates more spatially accurate quantization. 3D structures can be determined in one of two ways. If the nanoparticle has a homogeneous structure, then 2D projection images of different particles can be averaged using a computational process referred to as single particle reconstruction. Alternatively, if the nanoparticle has a heterogeneous structure, then a structure can be generated by cryo-ET. This involves collecting a tilt-series of 2D projection images for a defined region of the grid, which can be used to generate a 3D tomogram. Occasionally it is advantageous to calculate both a single particle reconstruction, to reveal the regular portions of a nanoparticle structure, and a cryo-electron tomogram, to reveal the irregular features. A sampling of 2D cryo-TEM images and 3D structures are presented for protein based, DNA based, lipid based, and polymer based nanoparticles. WIREs Nanomed Nanobiotechnol 2017, 9:e1417. doi: 10.1002/wnan.1417 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

  11. Analysis of Induced Polarization effects in airborne TEM data - a case study from central East Greenland

    Science.gov (United States)

    Maack Rasmussen, Thorkild; Brethes, Anaïs; Pierpaolo Guarnieri, Pierpaolo; Bauer, Tobias

    2017-04-01

    Data from a high-resolution airborne SkyTEM time-domain electromagnetic survey conducted in central East Greenland were analysed. An analysis based on utilization of a Self Organizing Map procedure for response curve characterization and analyses based on data inversion and modelling are presented. The survey was flown in 2013 along the eastern margin of the Jameson Land basin with the purpose of base metal exploration and with sulphide mineralization as target. The survey area comprises crystalline basement to the East and layered Early Triassic to Jurassic sediments to the West. The layers are dipping a few degrees towards West. The Triassic sequence is 1 to 2 km thick and mostly of continental origin. The fluviatile Early Triassic arkoses and conglomerates, the Upper Triassic grey limestone and black shale beds and overlying gypsiferous sandstones and mudstones are known to host disseminated sulphides. E-W oriented lines were flown with an average terrain clearance of 30m and a separation of 300m. The data were initially processed and inverted by SkyTEM Aps. The conductivity models showed some conductive layers as well as induced polarization (IP) effects in the data. IP effects in TEM data reflect the relaxation of polarized charges in the ground which can be good indicators of the presence of metallic particles. Some of these locations were drilled during the following field season but unfortunately did not reveal the presence of mineralization. The aim of this study is therefore to understand the possible causes of these IP effects. Electrical charge accumulation in the ground can be related to the presence of sulphides, oxides or graphite or to the presence of clays or fibrous minerals. Permafrost may also cause IP effects and is then expected to be associated with a highly resistive subsurface. Several characteristics of the transient curves (IP indicators) of the SkyTEM survey were extracted and analysed by using the Kohonen Self-Organizing Map (SOM

  12. Benefits from bremsstrahlung distribution evaluation to get unknown information from specimen in SEM and TEM

    Science.gov (United States)

    Eggert, F.; Camus, P. P.; Schleifer, M.; Reinauer, F.

    2018-01-01

    The energy-dispersive X-ray spectrometer (EDS or EDX) is a commonly used device to characterise the composition of investigated material in scanning and transmission electron microscopes (SEM and TEM). One major benefit compared to wavelength-dispersive X-ray spectrometers (WDS) is that EDS systems collect the entire spectrum simultaneously. Therefore, not only are all emitted characteristic X-ray lines in the spectrum, but also the complete bremsstrahlung distribution is included. It is possible to get information about the specimen even from this radiation, which is usually perceived more as a disturbing background. This is possible by using theoretical model knowledge about bremsstrahlung excitation and absorption in the specimen in comparison to the actual measured spectrum. The core aim of this investigation is to present a method for better bremsstrahlung fitting in unknown geometry cases by variation of the geometry parameters and to utilise this knowledge also for characteristic radiation evaluation. A method is described, which allows the parameterisation of the true X-ray absorption conditions during spectrum acquisition. An ‘effective tilt’ angle parameter is determined by evaluation of the bremsstrahlung shape of the measured SEM spectra. It is useful for bremsstrahlung background approximation, with exact calculations of the absorption edges below the characteristic peaks, required for P/B-ZAF model based quantification methods. It can even be used for ZAF based quantification models as a variable input parameter. The analytical results are then much more reliable for the different absorption effects from irregular specimen surfaces because the unknown absorption dependency is considered. Finally, the method is also applied for evaluation of TEM spectra. In this case, the real physical parameter optimisation is with sample thickness (mass thickness), which is influencing the emitted and measured spectrum due to different absorption with TEM

  13. Ostwald ripening in a Pt/SiO2 model catalyst studied by in situ TEM

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chorkendorff, Ib; Dahl, Søren

    2011-01-01

    by the Ostwald ripening mechanism. The in situ TEM images also provide information about the temporal evolution of the Pt particle size distribution and of the growth or decay of the individual nanoparticles. The observed Pt nanoparticle changes compare well with predictions made by mean-field kinetic models...... for ripening, but deviations are revealed for the time-evolution for the individual nanoparticles. A better description of the individual nanoparticle ripening is obtained by kinetic models that include local correlations between neighboring nanoparticles in the atom-exchange process....

  14. El territorio agrorrural no es un parque temático

    OpenAIRE

    Segrelles, José Antonio

    2014-01-01

    Un parque natural agrario (PNA) y el territorio que lo alberga no son un parque temático o etnográfico, un museo viviente o una simple reserva natural. Tampoco son una forma de momificación del espacio agropecuario. Un PNA es un instrumento de gestión eficiente de las actividades agrícolas, ganaderas y forestales, además de un agroecosistema con entidad propia que ayuda a conservar el territorio, a garantizar la continuidad agrícola del suelo y a fomentar la ejecución de programas concretos d...

  15. Vídeo del Eje temático 2. Servicios y calidad

    OpenAIRE

    Unidad de Recursos de Información Científica para la Investigación (URICI)

    2012-01-01

    Eje temático 2. Servicios y calidad Moderado por Ricardo Martínez de Madariaga, Biblioteca del Centro de Física Teórica y Matemáticas.- Comunicación: ¿De qué se habla cuando se habla de calidad de los servicios? (Carina Rey, profesora titular de la Universidad de Barcelona).- Indicadores y carta de servicios en las bibliotecas del CSIC (Juan Pedro López Monjón, Unidad de Recursos de Información Científica para la Investigación).- Servicios y calidad, la visión de las bibliotecas (Marina Gó...

  16. In-situ irradiation of cerium precursors in TEM to study nanocrystal formation

    Science.gov (United States)

    Asghar, Muhammad Sajid Ali; Sabri, Mohammed Mohammed; Tian, Zijian; Möbus, Günter

    2017-09-01

    Three of the most commonly used precursor chemicals for wet-chemical nano-ceria synthesis are examined by means of direct dry electron irradiation in TEM. Transformation reactions of micron-size carbonate, chloride, and nitrate grains into nanocrystallites (internal or external) are recorded in situ. Progress of possible redox-changes of cerium is tracked by EELS. We find a straight local oxidation reaction for carbonates, but external nanorod formation by condensation in the case of chlorides, while nitrates show a multi-stage complex redox behaviour.

  17. TEM-based Pair Distribution Function study of interatomic distances in C-supported Pt

    Science.gov (United States)

    Tran, D. T.; Ozkaya, D.

    2017-09-01

    The interatomic distances have been characterised for a Pt on Carbon based fuel cell catalyst studied by analysing the atomic pair distribution functions (PDF) obtained from electron diffraction (ED) data taken in a transmission electron microscope (TEM). The experimental PDFs have been compared with atomistic models to examine C-C and Pt-Pt interatomic distances. Further, the models have been refined by reverse Monte-Carlo simulations (RMC) based on the experimental PDF, enabling the investigation of Pt-C interatomic distances. This has demonstrated the existence of an interatomic contact between the Pt and C.

  18. Creation of a sharper focus by using a rectified TEM p0 beam

    Science.gov (United States)

    Hasnaoui, A.; Bencheikh, A.; Fromager, M.; Cagniot, E.; Aït-Ameur, K.

    2011-03-01

    The superresolution technique is usually used in optical imaging for its ability to make the central diffractive spot smaller than the Airy spot. In this paper, we apply the superresolution technique for transforming a symmetrical TEMp0 Laguerre-Gauss beam into a Gaussian intensity distribution in the plane of a converging lens. The beam shaping is achieved by an annular binary Diffractive Optical Element having a transmittance, alternatively equal to -1 or + 1, modelled on the p light rings of the incident beam. It is observed that the rectified TEM30 beam at focus has a focal volume 170 times smaller than that of a Gaussian beam.

  19. In Situ Laser Synthesis of Si Nanowires in the Dynamic TEM

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, M; Reed, B; LaGrange, T; Browning, N

    2007-12-05

    Nanowires (NWs) are a crucial component in today's nanoscale devices and are vital to the further development of nanotechnology. To achieve reliable growth of NWs and uniform electronic properties, the specific mechanisms that control the structural development of NWs and the correlation between NWs and their nucleation and growth processes must be examined. Because imaging is not possible in Chemical Vapor Deposition (CVD) chambers, in situ transmission electron microscope (TEM) based growth methods provide a method for characterizing NW evolution. In this paper, we describe a new method of in situ synthesis and imaging of NWs using laser-assisted growth inside a TEM. The vapor-liquid solid (VLS) growth mechanism (Figure 1), first described by Wagner and co-workers, is a widely accepted description of how many 1D nanostructures are formed. VLS and similar models have been applied to such methods as hybrid pulsed-laser ablation/chemical vapor deposition (PLA/CVD) and laser assisted NW growth at elevated temperatures, in which a pulsed laser ablates a target with gas flowing through the reaction chamber held at elevated temperature. These methods have successfully produced semiconductor and conducting oxide NWs with size control determined by the catalyst droplet diameter. The VLS description of NW growth is a widely accepted model, but the exact role of vapor species and its interaction with the catalyst particle is not fully understood. For example, NW growth has been observed to occur far below predicted eutectic temperatures, which suggests that alternative mechanisms such as solid-liquid-solid growth (SLS) may play a role. Many NW fabrication techniques preclude direct in situ characterization of the growth process. Because of this need for direct observation during growth, TEM-based NW growth methods have become increasingly popular. Though progress has been made in the study of the VLS mechanism of NW growth using in situ TEM, conventional in situ growth

  20. Low-pressure Environmental TEM (ETEM) studies of Au assisted MgO nanorod growth

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Damsgaard, Christian Danvad; Hansen, Thomas Willum

    2012-01-01

    and interface structure of supported nanoparticles in a controlled environment [7]. This allows for a deeper understanding of the dynamic response of the surface and interface to changes in gas composition, pressure and temperature. Additionally, an Ultra High Vacuum (UHV) TEM has been used in order to have...... about the crystal structure of their surfaces is often obtained from measurements that are averaged over large numbers of particles. Furthermore, the catalytic activity depends on the support and hence on the interaction between support and catalyst nanoparticle. Supported Au nanoparticles are active...

  1. Evaluation of TEG(®) and RoTEM(®) inter-changeability in trauma patients

    DEFF Research Database (Denmark)

    Hagemo, Jostein S; Næss, Paal A; Johansson, Pär

    2013-01-01

    BACKGROUND: Massive haemorrhage is a leading cause of preventable deaths in trauma. Traumatic coagulopathy is frequently present early after trauma, and is associated with increased mortality. A number of recent trials suggest that viscoelastic haemostatic assays (VHA), such as thromboelastography...... values for the two devices was 0.24 for the R-time vs CT in all centres combined. For the K-time vs CFT the correlation was 0.48, for the α-angle(TEG) vs α-angle(RoTEM) 0.44, and for MA vs MCF 0.76. Limits of agreement exceeded the preset clinically acceptable deviation of 10% for all variables in all...

  2. An in-situ TEM investigation of He bubble evolution in SiC

    OpenAIRE

    Pawley, C J; Beaufort, M.F.; Oliviero, E.; Hinks, J. A.; Barbot, J F; Donnelly, S. E.

    2012-01-01

    This paper presents work using the capabilities of two TEM with in-situ ion\\ud irradiation facilities: Microscope and Ion Accelerator for Materials Investigation (MIAMI) at\\ud the University of Huddersfield and Joint Accelerators for Nano-science and Nuclear\\ud Simulation JANNuS at Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse\\ud (CSNSM), Orsay, France, to study the nucleation and growth of He bubbles in silicon carbide\\ud (SiC) and to carry out an investigation into bubble b...

  3. Descripción temática de los encuentros de asocolme, 2008-2010

    OpenAIRE

    Gómez, Pedro; Cañadas, María C.; Restrepo, Ángela M.; Bracho, Rafael; Aristizábal, Guillermo

    2011-01-01

    En este trabajo presentamos un análisis temático de los trabajos publicados en las actas de los encuentros de la Asociación Colombiana de Matemática Educativa (ASOCOLME) entre 2008 y 2010. Estos trabajos fueron codificados con base en una clasificación conceptual específica a la Educación Matemática. Los resultados de la codificación se analizaron en términos de frecuencias y porcentajes, distinguiendo aquellos documentos que son de investigación de aquellos que no lo son. Los resultados mues...

  4. Structural and functional alterations of cellular components as revealed by electron microscopy.

    Science.gov (United States)

    Condello, Maria; Caraglia, Michele; Castellano, Maria; Arancia, Giuseppe; Meschini, Stefania

    2013-10-01

    Scanning (SEM) and transmission electron microscopy (TEM) are two fundamental microscopic techniques widely applied in biological research for the study of ultrastructural cell components. With these methods, especially TEM, it is possible to detect and quantify the morphological and ultrastructural parameters of intracellular organelles (mitochondria, Golgi apparatus, lysosomes, peroxisomes, endosomes, endoplasmic reticulum, cytoskeleton, nucleus, etc.) in normal and pathological conditions. The study of intracellular vesicle compartmentalization is raising even more interest in the light of the importance of intracellular localization of mediators of the signaling in eliciting different biological responses. The study of the morphology of some intracellular organelles can supply information on the bio-energetic status of the cells. TEM has also a pivotal role in the determination of different types of programmed cell death. In fact, the visualization of autophagosomes and autophagolysosomes is essential to determine the occurrence of autophagy (and also to discriminate micro-autophagy from macro-autophagy), while the presence of fragmented nuclei and surface blebbing is characteristic of apoptosis. SEM is particularly useful for the study of the morphological features of the cells and, therefore, can shed light, for instance, on cell-cell interactions. After a brief introduction on the basic principles of the main electron microscopy methods, the article describes some cell components with the aim to demonstrate the huge role of the ultrastructural analysis played in the knowledge of the relationship between function and structure of the biological objects. Copyright © 2013 Wiley Periodicals, Inc.

  5. Computer-aided microtomography with true 3-D display in electron microscopy.

    Science.gov (United States)

    Nelson, A C

    1986-01-01

    A novel research system has been designed to permit three-dimensional (3-D) viewing of high resolution image data from transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The system consists of front-end primary data acquisition devices, such as TEM and SEM machines, which are equipped with computer-controlled specimen tilt stages. The output from these machines is in analogue form, where a video camera attached to the TEM provides the sequential analogue image output while the SEM direct video output is utilized. A 10 MHz digitizer transforms the video image to a digital array of 512 X 512 pixel units of 8 bits deep-stored in a frame buffer. Digital images from multiple projections are reconstructed into 3-D image boxes in a dedicated computer. Attached to the computer is a powerful true 3-D display device which has hardware for graphic manipulations including tilt and rotate on any axis and for probing the image with a 3-D cursor. Data editing and automatic contouring functions are used to enhance areas of interest, and specialized software is available for measurement of numbers, distances, areas, and volumes. With proper archiving of reconstructed image sequences, a dynamic 3-D presentation is possible. The microtomography system is highly versatile and can process image data on-line or from remote sites from which data records would typically be transported on computer tape, video tape, or floppy disk.

  6. Transmission electron microscopy a textbook for materials science

    CERN Document Server

    Williams, David B

    1996-01-01

    Electron microscopy has revolutionized our understanding the extraordinary intellectual demands required of the mi­ of materials by completing the processing-structure-prop­ croscopist in order to do the job properly: crystallography, erties links down to atomistic levels. It now is even possible diffraction, image contrast, inelastic scattering events, and to tailor the microstructure (and meso structure ) of materials spectroscopy. Remember, these used to be fields in them­ to achieve specific sets of properties; the extraordinary abili­ selves. Today, one has to understand the fundamentals ties of modem transmission electron microscopy-TEM­ of all of these areas before one can hope to tackle signifi­ instruments to provide almost all of the structural, phase, cant problems in materials science. TEM is a technique of and crystallographic data allow us to accomplish this feat. characterizing materials down to the atomic limits. It must Therefore, it is obvious that any curriculum in modem mate­ be use...

  7. Multifarious applications of atomic force microscopy in forensic science investigations.

    Science.gov (United States)

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

    2017-04-01

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

  8. Correlation of superconducting properties and microstructure in MgB{sub 2} using SEM, EPMA and TEM

    Energy Technology Data Exchange (ETDEWEB)

    Birajdar, Balaji I.

    2008-04-14

    This thesis can be subdivided as follows: (I) Development of the quantitative electron microscopy and spectroscopy methods essential for the microstructural analysis of MgB{sub 2} and thereby assess the performance of two energy-filtered TEMs. (II) Application of these methods to few selected samples: (a) Pure and Al-alloyed MgB{sub 2} bulk samples prepared by solid-state reaction or by mechanical alloying, (b) In-situ and ex-situ MgB{sub 2} wires and tapes with and without SiC additives prepared by different variants of the powder-in-tube technology. Quantitative B analysis by EDX spectroscopy was applied in the SEM and TEM, which is a major achievement. (III) Establishing a model which quantitatively explains the correlation between microstructure and critical current density as a function of magnetic field. The actual Al mole fraction in the MgB{sub 2} matrix was found to be less than the nominal Al mole fraction and the difference increased with increasing Al mole fraction. Al is incorporated into MgB{sub 2} grains of {approx}1{mu}m size by substitution of Mg atoms causing T{sub c} and c lattice parameter to decrease at a rate of 1.56 K and 1.15 pm per at.% of Al alloying. Precipitation of Al was not detected up to highest Al mole fractions but Al was inhomogeneously distributed in the sample, which explained the broadening of the superconducting transition width ({delta}T{sub c}) with increasing Al mole fraction. For wires and tapes, significant differences were observed in the microstructure of in-situ and ex-situ samples. This holds particularly if SiC was added and yielded Mg{sub 2}Si for in-situ samples annealed at 600 -650 C and Mg-Si-O phases for ex-situ samples annealed between 900 -1050 C. Four microstructural parameters were identified as relevant for the I{sub c} of wires and tapes and these were: 1) MgB{sub 2} grain size which lies in the range of 20-1000 nm, 2) colony size (colony is a dense arrangement of MgB{sub 2} grains) which lies in the range

  9. In Situ Transmission Electron Microscopy Characterization and Manipulation of Two-Dimensional Layered Materials beyond Graphene.

    Science.gov (United States)

    Luo, Chen; Wang, Chaolun; Wu, Xing; Zhang, Jian; Chu, Junhao

    2017-09-01

    Two-dimensional (2D) ultra-thin materials beyond graphene with rich physical properties and unique layered structures are promising for applications in electronics, chemistry, energy, and bioscience, etc. The interaction mechanisms among the structures, chemical compositions and physical properties of 2D layered materials are critical for fundamental nanosciences and the practical fabrication of next-generation nanodevices. Transmission electron microscopy (TEM), with its high spatial resolution and versatile external fields, is undoubtedly a powerful tool for the static characterization and dynamic manipulation of nanomaterials and nanodevices at the atomic scale. The rapid development of thin-film and precision microelectromechanical systems (MEMS) techniques allows 2D layered materials and nanodevices to be probed and engineered inside TEM under external stimuli such as thermal, electrical, mechanical, liquid/gas environmental, optical, and magnetic fields at the nanoscale. Such advanced technologies leverage the traditional static TEM characterization into an in situ and interactive manipulation of 2D layered materials without sacrificing the resolution or the high vacuum chamber environment, facilitating exploration of the intrinsic structure-property relationship of 2D layered materials. In this Review, the dynamic properties tailored and observed by the most advanced and unprecedented in situ TEM technology are introduced. The challenges in spatial, time and energy resolution are discussed also. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Cryo-FIB specimen preparation for use in a cartridge-type cryo-TEM.

    Science.gov (United States)

    He, Jie; Hsieh, Chyongere; Wu, Yongping; Schmelzer, Thomas; Wang, Pan; Lin, Ying; Marko, Michael; Sui, Haixin

    2017-08-01

    Cryo-electron tomography (cryo-ET) is a well-established technique for studying 3D structural details of subcellular macromolecular complexes and organelles in their nearly native context in the cell. A primary limitation of the application of cryo-ET is the accessible specimen thickness, which is less than the diameters of almost all eukaryotic cells. It has been shown that focused ion beam (FIB) milling can be used to prepare thin, distortion-free lamellae of frozen biological material for high-resolution cryo-ET. Commercial cryosystems are available for cryo-FIB specimen preparation, however re-engineering and additional fixtures are often essential for reliable results with a particular cryo-FIB and cryo-transmission electron microscope (cryo-TEM). Here, we describe our optimized protocol and modified instrumentation for cryo-FIB milling to produce thin lamellae and subsequent damage-free cryotransfer of the lamellae into our cartridge-type cryo-TEM. Published by Elsevier Inc.

  11. Metodología de la investigación temática

    Directory of Open Access Journals (Sweden)

    Joao Bosco

    2015-05-01

    Full Text Available El origen histórico de la Investigación Temática está vinculado con el trabajo de la educación de adultos, del pedagogo brasileño Paulo Freire, en base a un método Psicosocial. Quienes están dedicados a la práctica de este método se han dado cuenta de su riqueza metodológica y han empezado a formular con mayor claridad sus supuestos teóricos y desglosar su desarrollo como metodología investigativa y como práctica social. Actualmente, se está utilizando la investigación temática en EE.UU., Colombia, Chile, Perú, Bolivia, Venezuela y otros países, la misma que nació en parte como fruto de una insatisfacción con las metodologías tradicionales de investigación social.

  12. Evaluation and mapping of Dead Sea coastal aquifers salinity using Transient Electromagnetic (TEM) resistivity measurements

    Science.gov (United States)

    Ezersky, Michael G.; Frumkin, Amos

    2017-01-01

    Evaporite karst has intensively developed recently along the Dead Sea (DS) coastal area in Israel and Jordan. It takes place in very saline groundwater dissolving buried salt layers, causing collapse of the surface. In this paper, groundwater salinity throughout the DS coastal area is investigated using the Transient Electromagnetic (TEM) method. Twenty-eight TEM soundings along the DS coastal area were carried out close to observation boreholes to calibrate resistivity-salinity relationships. Groundwater electrical conductivity was measured in these boreholes, and its salinity was analyzed at the laboratory by the Geological Survey of Israel (GSI). Quantitative relationships between bulk resistivity (ρx), water resistivity (ρw) and chloride concentration (Ccl) were derived in the resistivity range less than 1.0 Ω·m that enabled to evaluate the salinity of the aquifer in in situ conditions. Average values of the effective porosity of sandy sediments, φe = 0.32, and of silty ones, φe = 0.44, were used to generate the corresponding Archie equations. The study has shown that a DS aquifer with bulk resistivity in the range of 0.55-1.0 Ω·m contains in pores brine with 50-110 gchloride/l of (22-50% of that in saturated conditions, respectively), i.e. it keeps the potential to dissolve up to 114-174 g/l of salt.

  13. [Bacterial TEM-type serine beta-lactamases: structure and analysis of mutations].

    Science.gov (United States)

    Grigorenko, V G; Rubtsova, M Yu; Uporov, I V; Ishtubaev, I V; Andreeva, I P; Shcherbinin, D S; Veselovsky, A V; Egorov, A M

    2017-11-01

    Beta-lactamases (EC 3.5.2.6) represent a superfamily containing more than 2,000 members: it includes genetically and functionally different bacterial enzymes capable to destroy the beta-lactam antibiotics. The most common are beta-lactamases of molecular class A with serine in the active center. Among them, TEM-type beta-lactamases are of particular interest from the viewpoint of studying the mechanisms of the evolution of resistance due to their broad polymorphism. To date, more than 200 sequences of TEM-type beta-lactamases have been described and more than 60 structures of different mutant forms have been presented in Protein Data Bank. We have considered the main structural features of the enzymes of this type with particular attention to the analysis of key drug resistance and the secondary mutations, their location relative to the active center and the surface of the protein globule. We have developed the BlaSIDB database (www.blasidb.org) which is an open information resource combining available data on 3D structures, amino acid sequences and nomenclature of the corresponding forms of beta-lactamases.

  14. Structural changes in collagen fibrils across a mineralized interface revealed by cryo-TEM.

    Science.gov (United States)

    Quan, Bryan D; Sone, Eli D

    2015-08-01

    The structure of the mineralized collagen fibril, which is the basic building block of mineralized connective tissues, is critical to its function. We use cryo-TEM to study collagen structure at a well-defined hard-soft tissue interface, across which collagen fibrils are continuous, in order to evaluate changes to collagen upon mineralization. To establish a basis for the analysis of collagen banding, we compared cryo-TEM images of rat-tail tendon collagen to a model based on the X-ray structure. While there is close correspondence of periodicity, differences in band intensity indicate fibril regions with high density but lacking order, providing new insight into collagen fibrillar structure. Across a mineralized interface, we show that mineralization results in an axial contraction of the fibril, concomitant with lateral expansion, and that this contraction occurs only in the more flexible gap region of the fibril. Nevertheless, the major features of the banding pattern are not significantly changed, indicating that the axial arrangement of molecules remains largely intact. These results suggest a mechanism by which collagen fibrils are able to accommodate large amounts of mineral without significant disruption of their molecular packing, leading to synergy of mechanical properties. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. SIMS and TEM investigation of hydrogen trapping on implantation defects in a nickel-based superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Jambon, Fanny, E-mail: fanny.jambon@cea.fr [CEA, DEN, DPC, SCCME, Laboratoire d' Étude de la Corrosion Aqueuse, F-91191 Gif-Sur-Yvette Cedex (France); Marchetti, Loïc [CEA, DEN, DPC, SCCME, Laboratoire d' Étude de la Corrosion Aqueuse, F-91191 Gif-Sur-Yvette Cedex (France); CEA, DEN, DTCD, SECM, Laboratoire d' étude du Comportement à Long Terme des Matériaux de conditionnement, F-30207 Bagnols-sur-Cèze (France); Sennour, Mohamed [MINES ParisTech, PSL – Research University – Centre des Matériaux, UMR CNRS 7633, B.P. 87, 91003 Evry (France); Jomard, François [Groupe d' Etude de la Matière Condensée (CNRS and University of Versailles Saint Quentin), 45 avenue des Etats-Unis, 78035 Versailles Cedex (France); Chêne, Jacques [UMR 8587 CEA/CNRS, Équipe Hydrogène/Matériaux de structure, CEA, DEN, DPC, SCCME, Laboratoire d' Étude de la Corrosion Aqueuse, F-91191 Gif-Sur-Yvette Cedex (France)

    2015-11-15

    This study aims at characterizing the interactions of hydrogen with point defects and their clusters in nickel-based superalloys. For this, nickel ion implantation was used to create defects in the sub-surface of alloy 690 coupons. The interaction of hydrogen with these defects was studied thanks to SIMS depth profile analysis performed after deuterium cathodic charging, and different annealing treatment. In parallel, TEM observations were carried out in order to qualify and quantify the defects responsible for the trapping, and to observe their evolution in the presence of hydrogen. All the results exhibit a strong interaction of hydrogen with implantation-defects, up to high temperatures (325 °C). Also, hydrogen is shown to assist defects reorganisation, in a way similar to the effect of temperature. The effect of hydrogen on the alloy atoms as explored by SIMS, combined with the TEM investigation of defects evolution in the presence of hydrogen, allows to suggest that the main mechanism for hydrogen-assisted motion of defects is by lowering the lattice friction, thus decreasing the activation volume for the unfaulting or motion of point defect clusters, up to dislocation loops.

  16. Quantitative Electrochemical Measurements using in situ ec-S/TEM Devices

    Energy Technology Data Exchange (ETDEWEB)

    Unocic, Raymond R [ORNL; Sacci, Robert L [ORNL; Brown, Gilbert M [ORNL; Veith, Gabriel M [ORNL; Dudney, Nancy J [ORNL; More, Karren Leslie [ORNL; Gardiner, Daniel [Protochips Inc., Raleigh, NC; Walden II, Franklin S [Protochips Inc., Raleigh, NC; Damiano, John [Protochips Inc., Raleigh, NC; Nackashi, David P. [Protochips Inc., Raleigh, NC

    2014-01-01

    Insight into dynamic electrochemical processes can be obtained with in situ ec-S/TEM, which utilizes microfluidic electrochemical cells to characterize electrochemical processes with S/TEM imaging, diffraction or spectroscopy. The microfluidic electrochemical cell is composed of microfabricated devices with glassy carbon and platinum microband electrodes in a three-electrode cell configuration. To establish the validity of this method for quantitative in situ electrochemistry research, cyclic voltammetry, choronoamperometry and electrochemical impedance spectroscopy were performed using a standard one electron transfer redox couple using a [Fe(CN)6]3-/4- based electrolyte. Established relationships of the electrode geometry and microfluidic conditions were fitted with cyclic voltammetry and chronoamperometic measurements of analyte diffusion coefficients and was found to agree with well-accepted values that are on the order of 10-5 cm2 s-1. Influence of the electron beam on electrochemical measurements was found to be negligible during CV scans where the current profile varied only within a few nA with the electron beam on and off which is well within the hysteresis between multiple CV scans. The combination of experimental results provides a validation that quantitative electrochemistry experiments can be performed with these small-scale microfluidic electrochemical cells provided that accurate geometrical electrode configurations, diffusion boundary layers and microfluidic conditions are accounted for.

  17. TEM observation and fracture morphology in the CGHAZ of a new ...

    Indian Academy of Sciences (India)

    Unknown

    the grain boundaries decrease impact toughness in the CGHAZ of 0Cr18Mo2Ti steel by promoting crack initiation. In practical applications, the welding heat input (E) should be as low as possible to prevent tough- ness reduction in the CGHAZ. Keywords. Ferritic stainless steel; electron microscopy; microstructure; fracture; ...

  18. In situ TEM nanoindentation and dislocation-grain boundary interactions : a tribute to David Brandon

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Soer, W.A.; Minor, A.M.; Shan, Z.W.; Stach, E.A.; Asif, S.A.S.; Warren, O.L.

    2006-01-01

    As a tribute to the scientific work of Professor David Brandon, this paper delineates the possibilities of utilizing in situ transmission electron microscopy to unravel dislocation-grain boundary interactions. In particular, we have focused on the deformation characteristics of Al-Mg films. To this

  19. NICHD Microscopy and Imaging Core (MIC)

    Data.gov (United States)

    Federal Laboratory Consortium — The NICHD Microscopy and Imaging Core (MIC) is designed as a multi-user research facility providing training and instrumentation for high resolution microscopy and...

  20. Polyethyleneimine as tracer for electron microscopy

    NARCIS (Netherlands)

    Schurer, Jacob Willem

    1980-01-01

    In this thesis the development of a tracer particle for use in electron microscopy is described. Attempts were made to use this tracer particle in immuno-electron microscopy and to trace negatively charged tissue components. ... Zie: Summary

  1. Acoustic Microscopy at Cryogenic Temperatures.

    Science.gov (United States)

    1983-09-01

    L IIIIIrLL I~llI Illl ’.___- IImIIII...!~... 1.8 MICRO PY R[,oLUfroN uSF C HAPI NA: IN A t M I NC IA ACOUSTIC MICROSCOPY AT CRYOGENIC TEMPERATURES...ORGANIZATION NAME AND ADDRESS 10, PROGRAM ELEMENT. PROJECT, TASK Edward L. Ginzton Laboratory AREA & WORK UNfT UMBERS W.W. Hansen Laboratories of...microscope. As a follow-on to this work we are now planning to double the frequency to 8 GHz. The preliminary testing has been done and it now appears

  2. Diffraction phase and fluorescence microscopy.

    Science.gov (United States)

    Park, Yongkeun; Popescu, Gabriel; Badizadegan, Kamran; Dasari, Ramachandra R; Feld, Michael S

    2006-09-04

    We have developed diffraction phase and fluorescence (DPF) microscopy as a new technique for simultaneous quantitative phase imaging and epi-fluorescence investigation of live cells. The DPF instrument consists of an interference microscope, which is incorporated into a conventional inverted fluorescence microscope. The quantitative phase images are characterized by sub-nanometer optical path-length stability over periods from milliseconds to a cell lifetime. The potential of the technique for quantifying rapid nanoscale motions in live cells is demonstrated by experiments on red blood cells, while the composite phase-fluorescence imaging mode is exemplified with mitotic kidney cells.

  3. Microscopy using randomized speckle illumination

    Science.gov (United States)

    Perinchery, Sandeep M.; Shinde, Anant; Murukeshan, V. M.

    2017-06-01

    It is well known for structured illumination microscopy (SIM) that the lateral resolution by a factor of two beyond the classical diffraction limit is achieved using spatially structured illumination in wide-field fluorescence microscope. In the state of art SIM systems, grating patterns are generally generated by physical gratings or by spatial light modulators such as digital micro mirrors (DMD), liquid crystal displays (LCD). In this study, using a combination of LCD and ground glasses, size controlled randomized speckle patterns are generated as an illumination source for the microscope. Proof of concept of using speckle illumination in SIM configuration is tested by imaging fixed BPAE cells.

  4. Visual-servoing optical microscopy

    Science.gov (United States)

    Callahan, Daniel E.; Parvin, Bahram

    2009-06-09

    The present invention provides methods and devices for the knowledge-based discovery and optimization of differences between cell types. In particular, the present invention provides visual servoing optical microscopy, as well as analysis methods. The present invention provides means for the close monitoring of hundreds of individual, living cells over time: quantification of dynamic physiological responses in multiple channels; real-time digital image segmentation and analysis; intelligent, repetitive computer-applied cell stress and cell stimulation; and the ability to return to the same field of cells for long-term studies and observation. The present invention further provides means to optimize culture conditions for specific subpopulations of cells.

  5. Estudio del funcionamiento diferencial de los ítems en una Escala de Habilidades Sociales para Adolescentes

    OpenAIRE

    Hidalgo Montesinos, María Dolores; Galindo Garre, Francisca; Inglés Saura, Cándido José; Campoy Menéndez, Guillermo; Ortiz Soria, Beatriz

    1999-01-01

    Este trabajo tiene como objetivo estudiar el posible funcionamiento diferencial de los ítems (DIF) que componen la Escala de Habilidades Sociales para Adolescentes (EHSPA) como una parte del proceso de análisis de ítems. Este estudio implementa dos procedimientos de detección del DIF (estadístico de Mantel-Haenszel y Modelos Logit) para examinar si los ítems de la EHSPA funcionan de forma distinta en grupos igualados en función del género.

  6. Data on characterization of nano- and micro-structures resulting from glycine betaine surfactant/kappa-carrageenan interactions by Laser Scanning Confocal Microscopy and Transmission Electron Microscopy.

    Science.gov (United States)

    Gaillard, Cédric; Wang, Yunhui; Covis, Rudy; Vives, Thomas; Benoit, Maud; Benvegnu, Thierry

    2016-12-01

    This article contains data on the Laser Scanning Confocal Microscopy (LSCM) and Transmission Electron Microscopy (TEM) images related to multi-scaled self-assemblies resulting from 'green' cationic glycine betaine surfactant/anionic kappa-carrageenan interactions. These data gave clear evidence of the evolution of the micron-, nano-sized structures obtained at two surfactant/polymer molar ratios (3.5 and 0.8) and after the dilution of the aqueous dispersions with factors of 5 and 10 times. This data article is related to the research article entitled, "Monitoring the architecture of anionic ĸ-carrageenan/cationic glycine betaine amide surfactant assemblies by dilution: A multiscale approach" (Gaillard et al., 2017) [1].

  7. A quasi-time-resolved CryoTEM study of the nucleation of CaCO3 under langmuir monolayers.

    Science.gov (United States)

    Pichon, Benoît P; Bomans, Paul H H; Frederik, Peter M; Sommerdijk, Nico A J M

    2008-03-26

    Calcium carbonate biomineralization uses complex assemblies of macromolecules that control the nucleation, growth, and positioning of the mineral with great detail. To investigate the mechanisms involved in these processes, for many years Langmuir monolayers have been used as model systems. Here, we descibe the use of cryogenic transmission electron microscopy in combination with selected area electron diffraction as a quasi-time-resolved technique to study the very early stages of this process. In this way, we assess the evolution of morphology, polymorphic type, and crystallographic orientation of the calcium carbonate formed. For this, we used a self-assembled Langmuir monolayer of a valine-based bisureido surfactant (1) spread on a CaCl2-containing subphase and deposited on a holey carbon TEM grid. In a controlled environment, the grid is exposed to an atmosphere containing NH3 and CO2 (the (NH4)2CO3 diffusion method) for precisely determined periods of time (reaction times 30-1800 s) before it was plunged into melting ethane. This procedure allows us to observe amorphous calcium carbonate (ACC) particles growing from a few tens of nanometers to hundreds of nanometers and then crystallizing to form [00.1] oriented vaterite. The vaterite in turn transforms to yield [10.0] oriented calcite. We also performed the reaction in the absence of monolayer or in the presence of a nondirective monolayer of surfactant containing an oligo(ethylene oxide) 2 head group. Both experiments also showed the formation of a transient amorphous phase followed by a direct conversion into randomly oriented calcite crystals. These results imply the specific though temporary stabilization of the (00.1) vaterite by the monolayer. However, experiments performed at higher CaCl2 concentrations show the direct conversion of ACC into [10.0] oriented calcite. Moreover, prolonged exposure to the electron beam shows that this transformation can take place as a topotactic process. The formation of

  8. Agreement between direct fluorescent microscopy and Ziehl ...

    African Journals Online (AJOL)

    Background: The sensitivity of smear microscopy for diagnosis of tuberculosis might be improved through treatment of sputum with sodium hypochlorite and application of fluorescent microscopy. This study aimed to determine the agreement between direct Fluorescent Microscopy and Ziehl-Neelsen concentration technique ...

  9. Plasmonics Enhanced Smartphone Fluorescence Microscopy

    KAUST Repository

    Wei, Qingshan

    2017-05-12

    Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

  10. ELECTRON MICROSCOPY OF RHODOTORULA GLUTINIS

    Science.gov (United States)

    Thyagarajan, T. R.; Conti, S. F.; Naylor, H. B.

    1962-01-01

    Thyagarajan, T. R. (Dartmouth Medical School, Hanover, N. H.), S. F. Conti, and H. B. Naylor. Electron microscopy of Rhodotorula glutinis. J. Bacteriol. 83:381–394. 1962.—The structure and manner of nuclear division in Rhodotorula glutinis was studied by electron microscopy of ultrathin sections. Parallel studies with the light microscope, employing conventional staining techniques and phase-contrast microscope observations on nuclei in living cells, were carried out. The nucleus is spherical to oval and is bounded by a nuclear membrane. Intranuclear structures, identified as nucleoli, and electron-transparent areas were observed. The nuclear membrane persists throughout the various stages of cell division. Observations of the nucleus with the electron microscope revealed that nuclear division occurs by a process of elongation and constriction similar to that seen in both living and stained cells. The fine structure of mitochondria and other components of the yeast cell and their behavior during cell division are described. The absence of vacuoles in actively dividing cells of Rhodotorula glutinis lends further support to the view that the vacuole is not an integral part of the nucleus. The results with the electron microscope generally support and considerably extend those obtained with living and stained cells. Images PMID:13921132

  11. Plasmonics Enhanced Smartphone Fluorescence Microscopy.

    Science.gov (United States)

    Wei, Qingshan; Acuna, Guillermo; Kim, Seungkyeum; Vietz, Carolin; Tseng, Derek; Chae, Jongjae; Shir, Daniel; Luo, Wei; Tinnefeld, Philip; Ozcan, Aydogan

    2017-05-18

    Smartphone fluorescence microscopy has various applications in point-of-care (POC) testing and diagnostics, ranging from e.g., quantification of immunoassays, detection of microorganisms, to sensing of viruses. An important need in smartphone-based microscopy and sensing techniques is to improve the detection sensitivity to enable quantification of extremely low concentrations of target molecules. Here, we demonstrate a general strategy to enhance the detection sensitivity of a smartphone-based fluorescence microscope by using surface-enhanced fluorescence (SEF) created by a thin metal-film. In this plasmonic design, the samples are placed on a silver-coated glass slide with a thin spacer, and excited by a laser-diode from the backside through a glass hemisphere, generating surface plasmon polaritons. We optimized this mobile SEF system by tuning the metal-film thickness, spacer distance, excitation angle and polarization, and achieved ~10-fold enhancement in fluorescence intensity compared to a bare glass substrate, which enabled us to image single fluorescent particles as small as 50 nm in diameter and single quantum-dots. Furthermore, we quantified the detection limit of this platform by using DNA origami-based brightness standards, demonstrating that ~80 fluorophores per diffraction-limited spot can be readily detected by our mobile microscope, which opens up new opportunities for POC diagnostics and sensing applications in resource-limited-settings.

  12. Light Sheet Fluorescence Microscopy (LSFM).

    Science.gov (United States)

    Adams, Michael W; Loftus, Andrew F; Dunn, Sarah E; Joens, Matthew S; Fitzpatrick, James A J

    2015-01-05

    The development of confocal microscopy techniques introduced the ability to optically section fluorescent samples in the axial dimension, perpendicular to the image plane. These approaches, via the placement of a pinhole in the conjugate image plane, provided superior resolution in the axial (z) dimension resulting in nearly isotropic optical sections. However, increased axial resolution, via pinhole optics, comes at the cost of both speed and excitation efficiency. Light sheet fluorescent microscopy (LSFM), a century-old idea made possible with modern developments in both excitation and detection optics, provides sub-cellular resolution and optical sectioning capabilities without compromising speed or excitation efficiency. Over the past decade, several variations of LSFM have been implemented each with its own benefits and deficiencies. Here we discuss LSFM fundamentals and outline the basic principles of several major light-sheet-based imaging modalities (SPIM, inverted SPIM, multi-view SPIM, Bessel beam SPIM, and stimulated emission depletion SPIM) while considering their biological relevance in terms of intrusiveness, temporal resolution, and sample requirements. Copyright © 2015 John Wiley & Sons, Inc.

  13. Multifunctional scanning ion conductance microscopy.

    Science.gov (United States)

    Page, Ashley; Perry, David; Unwin, Patrick R

    2017-04-01

    Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential-time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes). Using a multi-barrel probe format, SICM-related techniques can be employed to deposit nanoscale three-dimensional structures and further functionality is realized when SICM is combined with scanning electrochemical microscopy (SECM), with simultaneous measurements from a single probe opening up considerable prospects for multifunctional imaging. SICM studies are greatly enhanced by finite-element method modelling for quantitative treatment of issues such as resolution, surface charge and (tip) geometry effects. SICM is particularly applicable to the study of living systems, notably single cells, although applications extend to materials characterization and to new methods of printing and nanofabrication. A more thorough understanding of the electrochemical principles and properties of SICM provides a foundation for significant applications of SICM in electrochemistry and interfacial science.

  14. 3D multiplexed immunoplasmonics microscopy

    Science.gov (United States)

    Bergeron, Éric; Patskovsky, Sergiy; Rioux, David; Meunier, Michel

    2016-07-01

    Selective labelling, identification and spatial distribution of cell surface biomarkers can provide important clinical information, such as distinction between healthy and diseased cells, evolution of a disease and selection of the optimal patient-specific treatment. Immunofluorescence is the gold standard for efficient detection of biomarkers expressed by cells. However, antibodies (Abs) conjugated to fluorescent dyes remain limited by their photobleaching, high sensitivity to the environment, low light intensity, and wide absorption and emission spectra. Immunoplasmonics is a novel microscopy method based on the visualization of Abs-functionalized plasmonic nanoparticles (fNPs) targeting cell surface biomarkers. Tunable fNPs should provide higher multiplexing capacity than immunofluorescence since NPs are photostable over time, strongly scatter light at their plasmon peak wavelengths and can be easily functionalized. In this article, we experimentally demonstrate accurate multiplexed detection based on the immunoplasmonics approach. First, we achieve the selective labelling of three targeted cell surface biomarkers (cluster of differentiation 44 (CD44), epidermal growth factor receptor (EGFR) and voltage-gated K+ channel subunit KV1.1) on human cancer CD44+ EGFR+ KV1.1+ MDA-MB-231 cells and reference CD44- EGFR- KV1.1+ 661W cells. The labelling efficiency with three stable specific immunoplasmonics labels (functionalized silver nanospheres (CD44-AgNSs), gold (Au) NSs (EGFR-AuNSs) and Au nanorods (KV1.1-AuNRs)) detected by reflected light microscopy (RLM) is similar to the one with immunofluorescence. Second, we introduce an improved method for 3D localization and spectral identification of fNPs based on fast z-scanning by RLM with three spectral filters corresponding to the plasmon peak wavelengths of the immunoplasmonics labels in the cellular environment (500 nm for 80 nm AgNSs, 580 nm for 100 nm AuNSs and 700 nm for 40 nm × 92 nm AuNRs). Third, the developed

  15. Nanoscale Laser Terahertz Emission Microscopy

    DEFF Research Database (Denmark)

    Klarskov, Pernille; Kim, Hyewon; Colvin, Vicki L.

    2017-01-01

    Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight into the phys......Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight...... into the physics of charge transport, built-in fields, grain boundaries or surface states. We describe a new implementation of LTEM with a spatial resolution in the nanoscale regime based on a scattering-type near-field tip-based approach. We observe a spectral reshaping of the signal compared to conventional LTEM......-size-limited spatial resolution of ∼20 nm by imaging a gold nanorod using terahertz emission from the underlying substrate. This work enables for the first time the possibility of performing LTEM measurements on individual nanostructures....

  16. Anterior lens epithelium in cataract patients with retinitis pigmentosa - scanning and transmission electron microscopy study.

    Science.gov (United States)

    Andjelic, Sofija; Drašlar, Kazimir; Hvala, Anastazija; Hawlina, Marko

    2017-05-01

    In retinitis pigmentosa (RP) patients, relatively minor lens opacity in central part of posterior pole of the lens may cause disproportionate functional symptoms requiring cataract operation. To investigate the possible structural reasons for this opacity development, we studied the structure of the lens epithelium of patients with RP. The anterior lens capsule (aLC: basement membrane and associated lens epithelial cells, LECs) was obtained from cataract surgery and prepared for scanning and transmission electron microscopy (SEM and TEM). Both SEM and TEM show a number of abnormal features in the anterior lens epithelium of cataract patients with RP. The abnormalities appear mainly as holes, thinning and degradation of the epithelium, with the dimensions from cataractous lens. We suggest that the lens epithelium has a role in the development of the cataract in patients with RP. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  17. Atomic-resolution transmission electron microscopy of electron beam–sensitive crystalline materials

    KAUST Repository

    Zhang, Daliang

    2018-01-18

    High-resolution imaging of electron beam-sensitive materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with extremely low beam doses, the time-constrained search for crystal zone axes, the precise image alignment, and the accurate determination of the defocus value. We develop a suite of methods to fulfill these requirements and acquire atomic-resolution TEM images of several metal organic frameworks that are generally recognized as highly sensitive to electron beams. The high image resolution allows us to identify individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers. We also apply our methods to other electron beam–sensitive materials, including the organic-inorganic hybrid perovskite CH3NH3PbBr3.

  18. Transanal endoscopic microsurgery (TEM: a minimally invasive procedure for treatment of selected rectal neoplasms Microcirurgia endoscópica transanal (TEM: um procedimento minimamente invasivo para o tratamento de neoplasias selecionadas do reto

    Directory of Open Access Journals (Sweden)

    Sergio C. Nahas

    2010-03-01

    Full Text Available Transanal endoscopic microsurgery (TEM provides a minimally invasive alternative to radical surgery for excision of benign and malignant rectal tumors. TEM aims to provide an alternative to conventional abdominal surgery (low anterior resection or abdominoperineal amputations, which carries not inconsiderable morbidity and mortality. Based on review of the literature and in the authors experience, this review present the method and indications for TEM.A microcirurgia endoscópica transanal (TEM é procedimento alternativo minimamente invasivo ao tratamento cirúrgico radical para excisão de tumores benignos e malignos do reto. Ela oferece possibilidade operatória aos procedimentos cirúrgicos convencionais (ressecção anterior baixa ou amputações abdominoperineais, as quais acarretam alta morbimortalidade. Baseada na revisão da literatura e na experiência própria dos autores, esta revisão tem por objetivo apresentar o método e as indicações para a TEM.

  19. Kelvin probe force microscopy in liquid using electrochemical force microscopy

    Directory of Open Access Journals (Sweden)

    Liam Collins

    2015-01-01

    Full Text Available Conventional closed loop-Kelvin probe force microscopy (KPFM has emerged as a powerful technique for probing electric and transport phenomena at the solid–gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe–sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present. Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl and ionically-inactive (non-polar decane liquids by electrochemical force microscopy (EcFM, a multidimensional (i.e., bias- and time-resolved spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids, KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions. EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.

  20. Ultrastructural analysis of testicular tissue and sperm by transmission and scanning electron microscopy.

    Science.gov (United States)

    Chemes, Hector E

    2013-01-01

    Transmission electron microscopy (TEM) studies have provided the basis for an in-depth understanding of the cell biology and normal functioning of the testis and male gametes and have opened the way to characterize the functional role played by specific organelles in spermatogenesis and sperm function. The development of the scanning electron microscope (SEM) extended these boundaries to the recognition of cell and organ surface features and the architectural array of cells and tissues. The merging of immunocytochemical and histochemical approaches with electron microscopy has completed a series of technical improvements that integrate structural and functional features to provide a broad understanding of cell biology in health and disease. With these advances the detailed study of the intricate structural and molecular organization as well as the chemical composition of cellular organelles is now possible. Immunocytochemistry is used to identify proteins or other components and localize them in specific cells or organelles with high specificity and sensitivity, and histochemistry can be used to understand their function (i.e., enzyme activity). When these techniques are used in conjunction with electron microscopy their resolving power is further increased to subcellular levels. In the present chapter we will describe in detail various ultrastructural techniques that are now available for basic or translational research in reproductive biology and reproductive medicine. These include TEM, ultrastructural immunocytochemistry, ultrastructural histochemistry, and SEM.