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Electron Microscope Images (electron + microscope_image)
Kinds of Electron Microscope Images Selected AbstractsThe non-conserved C-terminal segments of Sine Oculis Homeobox (Six) proteins confer functional specificityGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 8 2009Brandon P. Weasner Scanning electron microscope image of a fly head, showing an extra eye field (red) lying on the ventral surface adjacent to the normal compound eye (red). This field results from the forced expression of mouse Six6, the vertebrate ortholog for the Drosophila optix gene. Please see the article by B. Weasner and J.P. Kumar in this issue. [source] Front Cover Picture: Laser & Photon.LASER & PHOTONICS REVIEWS, Issue 2 2010Rev. 4(2)/2010 Schematic of resonant transmission through nanohole array using electron microscope image of as-fabricated sample. With applications ranging from linear and nonlinear optics to sensing and spectroscopy, nanohole arrays are promising for compact device integration. (Picture: R. Gordon et al., pp. 311,335, in this issue) [source] Chromate reduction in wastewater at different pH levels using thin iron wires,A laboratory studyENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2005Li-Yang Chang Abstract The effectiveness of using thin zero-valent iron (Fe0) wires in the treatment of wastewater generated from a metal cleaning facility and with a pH in the range of 2 to 10 was examined. It was found that (1) when the sample containing low levels of total chromium (,14 mg/L) was mixed with iron wires at a pH of 3 to 8, 50 to 90% of the total chromium could be reduced in 4 h; (2) the initial reduction efficiency was pH-dependent: the lower the pH, the higher the reduction rate; (3) variations of solution pH, redox electrical potential, and electrical conductivity (EC) in samples were also pH-dependent; (4) the adsorption/reduction efficiency was limited by the diffusion of Cr(VI) from wastewater to the iron surface when the test duration was long; (5) when the initial pH = 3, iron corrosion and redox reaction dominated the reduction process; however, with pH = 8 or 10, corrosion, surface passivation, or metal precipitation could compete with reduction; (6) the used iron wires were still effective in chromium removal in new samples at pH = 3; and (7) some desorption of adsorbed chromium was observed in acidic samples when the test duration was long. Scanning electron microscope images and energy-dispersive X-ray spectra collected from iron samples also indicate that the efficiency of chromium adsorption/reduction is pH-dependent. Our results suggest that using zero-valent iron to polish acidic wastewater containing low contents of chromium and other heavy metals is feasible. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] Synthesis of Nanohole-Structured Single-Crystalline Platinum Nanosheets Using Surfactant-Liquid-Crystals and their Electrochemical CharacterizationADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Tsuyoshi Kijima Abstract Nanohole-structured single-crystalline Pt nanosheets have been synthesized by the borohydride reduction of Na2PtCl6 confined to the lyotropic liquid crystals (LLCs) of polyoxyethylene (20) sorbitan monooleate (Tween 80) with or without nonaethylene-glycol (C12EO9). The Pt nanosheets of around 4,10,nm in central thickness and up to 500,nm or above in diameter have a number of hexagonal-shaped nanoholes ,1.8,nm wide. High-resolution electron microscope images of the nanosheets showed atomic fringes with a spacing of 0.22,nm indicating that the nanosheets are crystallographically continuous through the nanoholed and non-holed areas. The inner-angle distributions for the hexagonal nanoholes indicate that the six sides of the nanoholes are walled with each two Pt (111), Pt (11) and Pt (010) planes. The formation mechanism of nanoholed Pt nanosheets is discussed on the basis of structural and compositional data for the resulting solids and their precursory LLCs, with the aid of similar nanohole growth observed for a Tween 80 free but oleic acid-incorporated system. It is also demonstrated that the nanoholed Pt nanostructures loaded on carbon exhibit fairly high electrocatalytic activity for oxygen reduction reaction and a high performance as a cathode material for polymer-electrolyte fuel cells, along with their extremely high thermostability revealed through the effect of electron-irradiation. [source] Processing of transmission electron microscope images for quantification of the layer dispersion degree in polymer-clay nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2009Amir H. Navarchian Abstract Quantification of the layered silicates dispersion level is necessary to more accurately evaluate the performance in polymer/clay nanocomposites. In this article, a new approach is developed to quantify the degree of exfoliation, intercalation, and immiscibility of layered silicates in polymer matrix, based on bright-dark pixel measurement (BDPM) in transmission electron microscope (TEM) images. Several examples of exfoliated, intercalated, and immiscible composites with different polymer and clay systems were examined. The method is capable of estimating the percent contribution of all morphologies present in the image. Comparing with X-ray diffraction (XRD) evidences, it is indicated that as a rule of thumb, the exfoliated structure is dominant whenever the exfoliation percent calculated by BDPM methodology is over 65%, no matter what kind of clay or polymer matrix is used. The intercalated structure can be ascribed to the images with exfoliation level less than 65%, but with the intercalation degree over 28%. Application of this method can facilitate the modeling or correlation of various nanocomposite properties with respect to exfoliation degree. A quantified relation is also possible between XRD and TEM using this approach. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Cardiomyocyte precursors and telocytes in epicardial stem cell niche: electron microscope imagesJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2010Mihaela Gherghiceanu Abstract A highly heterogeneous population of stem and progenitor cells has been described by light immunohistochemistry in the mammalian adult heart, but the ultrastructural identity of cardiac stem cells remains unknown. Using electron microscopy, we demonstrate the presence of cells with stem features in the adult mouse heart. These putative cardiac stem cells are small (6,10 ,m), round cells, with an irregular shaped nucleus, large nucleolus, few endoplasmic reticulum cisternae and mitochondria, but numerous ribosomes. Stem cells located in the epicardial stem cell niche undergo mitosis and apoptosis. Cells with intermediate features between stem cells and cardiomyocyte progenitors have also been seen. Moreover, electron microscopy showed that cardiomyocyte progenitors were added to the peripheral working cardiomyocytes. Telocytes make a supportive interstitial network for stem cells and progenitors in the stem cell niche. This study enhances the hypothesis of a unique type of cardiac stem cell and progenitors in different stages of differentiation. In our opinion, stem cells, cardiomyocyte progenitors and telocytes sustain a continuous cardiac renewal process in the adult mammalian heart. [source] Three-dimensional representation of curved nanowiresJOURNAL OF MICROSCOPY, Issue 3 2004Z. HUANG Summary Nanostructures, such as nanowires, nanotubes and nanocoils, can be described in many cases as quasi one-dimensional curved objects projecting in three-dimensional space. A parallax method to construct the correct three-dimensional geometry of such one-dimensional nanostructures is presented. A series of scanning electron microscope images was acquired at different view angles, thus providing a set of image pairs that were used to generate three-dimensional representations using a matlab program. An error analysis as a function of the view angle between the two images is presented and discussed. As an example application, the importance of knowing the true three-dimensional shape of boron nanowires is demonstrated; without the nanowire's correct length and diameter, mechanical resonance data cannot provide an accurate estimate of Young's modulus. [source] Facile synthesis of polyaniline hemispheres in diethyl ether/ice mixture solvent and growth mechanism studyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2010Hui-yan Ma Abstract By using the new methodology of synthesis of container structure, we demonstrate the ability to control an improved ice-templating method to synthesis of polyaniline (PANI) in the form of hemisphere. The influence of the synthetic parameters, such as the concentration of doping-acid, oxidant, and aniline on the morphologies of PANI structures, has been investigated. It is determined that the doping acid and the second solvent added (such as diethyl ether absolute) have great positive influence on the formation of product's micro-morphology. The structure and morphology of PANI hemispheres are characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) patterns, energy-dispersive X-ray analysis (EDX), optical microscope images, and scanning electron microscope images (SEM). The formation mechanism of hemispheres in this article is well suggested. PANI hemispheres have super performance in sensitivity, time response to NH3 compared with traditional polymerization at room temperature. This work extends the field of functional materials with complex container structure and offers a new green route to synthesis of hemispherical container structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3596,3603, 2010 [source] Effect of an anionic monomer on the pickering emulsion polymerization stabilized by titania hydrosolJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2009Xiaomei Song Abstract Polystyrene (PS) nanocomposite particles with high titania content are prepared by Pickering emulsion polymerization. A self-made titania hydrosol modified by an anionic monomer sodium styrene sulfonate (NaSS) is used as a stabilizer and photocatalyst. The stability of the emulsion system is greatly improved by the electrostatic interaction between negatively charged NaSS and positively charged titania nanoparticles. The nanocomposite spheres with the diameter of around 120 nm are highly charged, indicating titania-rich surfaces of latex particles. It is also proven by the field-emission transmission electron microscope and field-emission scanning electron microscope images. The well-defined core-shell structure of the obtained PS/titania composite particles is confirmed by the formation of fragile hollow titania nanospheres after thermogravimetric analysis tests. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5728,5736, 2009 [source] Crystal Structure and Characterization of Pure and Ag-Doped (La1,xYx)2Ba2CaCu5Oz (0,x,0.5) SuperconductorsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Pramoda Kumar Nayak Pure and 5 wt% of Ag-doped (La1,xYx)2Ba2CaCu5Oz superconducting compounds for x=0,0.5 have been prepared. Analysis of X-ray diffraction patterns shows that the samples are essentially in the single-phase form and they could be refined using the P4/mmm space group in a tetragonal cell. The typical lattice parameters are found to be a=b=3.879 Å, c=11.646 Å for x=0 and a=b=3.856 Å, c=11.576 Å for x=0.5 samples. The detailed crystal structure parameters are presented. The average grain size values from scanning electron microscope images are found to be in the order of 1,3 ,m. Temperature variations of ac susceptibility and electrical resistivity have been measured. Superconducting transitions with diamagnetic Tc ranging from 60 to 75 K have been observed, with the maximum Tc for the x=0.25 sample. Ag-doped samples exhibit improved inter-granular coupling and homogeneous oxygenation. [source] Effects of substrate bias and argon flux on the structure of titanium nitride films deposited by filtered cathodic arc plasmaPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2005Y. J. Zhang Abstract High-quality titanium nitride (TiN) films with nano-structure were prepared at ambient temperature on (111) silicon substrates by filtered cathodic arc plasma (FCAP) technology with an in-plane "S" filter. The effects of substrate bias and argon flux on the crystal grain size, roughness and preferred orientation were systematically investigated. It was found that the substrate bias and argon flux can affect the properties of TiN films effectively. Transmission electron microscope images showed that the crystal grain size was uniform and ranged from 10 nm to 5 nm. The results of X-ray diffraction and electron diffraction indicated that the degree of preferred orientation was more evident under high substrate bias and high argon flux. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Excitation energy transfer between luminescent centers of microcrystalline InGaNPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003Hisashi Kanie Abstract InGaN microcrystals were grown by nitridation of gallium and indium sulfide. Cathodoluminescence (CL) image observation of InGaN microcrystals at room temperature was performed under a scanning electron microscope at 3,5 kV with a beam diameter of 10 nm equipped with a monochromator. High-spatial-resolution monochromatic CL images composited with secondary electron microscope images showed each facet has uniform but different CL spectra, such as single or double peaked spectra at 420 and 460 nm. From the width of a dark zone and bright zone at the fringe of the facet in the monochromatic CL images taken at the two wavelengths the length of the excitation energy transfer was estimated as the diffusion length of the excited carriers. The ratios of the lifetimes of the radiative and nonradiative process of the excited carriers are calculated from the estimated diffusion lengths. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Some fundamental and technical aspects of the quantitative analysis of pharmaceutical drugs by matrix-assisted laser desorption/ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2005Lekha Sleno The purpose of the present paper was to study some of the underlying physical and technical aspects of high-throughput quantitative matrix-assisted laser desorption/ionization (MALDI) of small drug molecules. A prototype MALDI-triple quadrupole instrument equipped with a high repetition rate laser was employed. Initially, the detection limits and dynamic ranges for the quantitation of four drugs (quinidine, danofloxacin, ramipril and nadolol) were determined. Internal standards were carefully chosen for each of these analytes in terms of structure similarity and fragmentation pathways. Three organic matrices were tested for these assays, resulting in different crystallization behaviors and measurement reproducibilities. , -Cyano-4-hydroxycinnamic acid yielded the best results and was subsequently employed for the quantitative determination of all four analytes. Further experiments considered the role of laser energy and pulse rate on the ablated areas as well as ion signals. Light microscope and scanning electron microscope images allowed the examination of the ablated area of the MALDI spots. The images showed convincing evidence that the ablated area was virtually void of crystals after analysis, with no preferential removal of material in the center of the laser's path. Average values for the amount of material ablated were determined to be 3.9,±,0.5% of the total spot size, and as low as 19.5 attomoles of analyte were detectable for our most sensitive analyte, ramipril. It was calculated that, under these assay conditions, it was possible to accurately quantify less than 1 femtomole of all analytes with the use of appropriately pure internal standards. These studies showed very promising results for the quantitative nature of MALDI for small molecules with molecular weights less than 500,Da. Copyright © 2005 John Wiley & Sons, Ltd. [source] Generation of Nanopores Down to 10 nm for Use in Deep-Nulling InterferometryCHEMPHYSCHEM, Issue 2 2008Axel Wehling Dr. Abstract Scanning electron microscope images show that it is easy to generate nanopores on polycarbonate membranes with well-defined pore diameters by ion-track perforation and subsequent magnetron sputtering with metal. The size reduction of the nanopores during sputtering with gold is a linear function of time. Images of different angles and from the bottom side of the membrane show that the channels are the smallest very close to the surface of the metal layer, have a conelike shape, and reach about half as much into the polymer membranes as the metal-layer thickness. This topographical pore shape is ideal for use as optically coherent near-field sources in deep-nulling microscopy. We present the first results of significantly improved nulling stabilization in the presence (<2 nm optical pathway difference) and the absence (<0.6 nm optical pathway difference) of the nanoapertures in the focal region of a deep-nulling microscope. [source] | |||||||||||||||||||