Search results for "TRANSMISSION ELECTRON"
showing 10 items of 426 documents
Dynamic Diglyme-Mediated Self-Assembly of Gold Nanoclusters
2015
We report the assembly of gold nanoclusters by the nonthiolate ligand diglyme into discrete and dynamic assemblies. To understand this surprising phenomenon, the assembly of Au20(SC2H4Ph)15-diglyme into Au20(SC2H4Ph)15-diglyme-Au20(SC2H4Ph)15 is explored in detail. The assembly is examined by high-angle annular dark field scanning transmission electron microscopy, size exclusion chromatography, mass spectrometry, IR spectroscopy, and calorimetry. We establish a dissociation constant for dimer to monomer conversion of 20.4 μM. Theoretical models validated by transient absorption spectroscopy predict a low-spin monomer and a high-spin dimer, with assembly enabled through weak diglyme oxygen-g…
Muskelveränderungen durch Saugdrainagen Eine rasterelektronenmikroskopische, transmissionselektronenmikroskopische, lichtmikroskopische und morphomet…
1983
In die Ruckenmuskulatur von 22 mannlichen, ausgewachsenen Wistar-Ratten wurde ein Drainagesystem eingelegt und die Wirkung des Unterdruckes auf die Muskulatur analysiert. Nach kurzester Liegezeit waren die Drainagesysteme durch ein Koagulat verschlossen. Im Unterschied zu den Kontrolltieren, bei denen sich lediglich Fibrin-Gerinnsel und Erythrozyten-Konglomerationen fanden, sahen wir im Rasterelektronenmikroskop bei den mit Unterdruck behandelten Tieren intakte Muskeln im Lumen der Drainage. Fibrin, Muskelfasern und Erythrozyten bildeten einen Verschluspfropf, der das funktioneile System der Saugdrainage unwirksam werden lies. Veranderungen in drainagefernen Muskelbezirken konnten lichtmikr…
Compensation of missing wedge effects with sequential statistical reconstruction in electron tomography.
2014
Electron tomography (ET) of biological samples is used to study the organization and the structure of the whole cell and subcellular complexes in great detail. However, projections cannot be acquired over full tilt angle range with biological samples in electron microscopy. ET image reconstruction can be considered an ill-posed problem because of this missing information. This results in artifacts, seen as the loss of three-dimensional (3D) resolution in the reconstructed images. The goal of this study was to achieve isotropic resolution with a statistical reconstruction method, sequential maximum a posteriori expectation maximization (sMAP-EM), using no prior morphological knowledge about …
Transmission electron microscopy in molecular structural biology: A historical survey.
2015
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 im…
Polyamide-Based Fibers Containing Microwave-Exfoliated Graphite Nanoplatelets
2016
Exfoliated Graphite NanoPlatelets (GNP) have been obtained from Graphite Intercalation Compounds (GIC) subjected to thermal and microwave treatments. Accurate morphological and structural characterization of obtained GNP, performed to compare the degree of exfoliation, show that microwave-treated GNP, exhibit well-exfoliated structure, without any reduction in dimensions compared with the native GIC, differently to the thermal-treated ones. Microwave-treated GNP have been introduced in polyamide (PA) through melt-mixing to obtain nanocomposite that has been subjected to elongational flow, with the aim to improve the nanofiller dispersion and induce GNP orientation along the fiber direction.…
Impact of Ceramic and Metallic Nano-scaled Particles on Endothelial Cell Functionsin vitro
2007
The sections in this article are Introduction Origin of Particles in the Human Environment Evidence for Size-dependent Toxicity of Particles Dissemination and Interferences of Nanoparticles within the Body Endothelial Cells and Nanoparticle Exposure Testing of Nanoparticle-induced Effects on Human Endothelial Cells In Vitro Materials and Methods Cell Culture Particles Transmission Electron Microscopy (TEM) Cytotoxicity Assay Detection of Ki67 Expression Quantification of IL-8 Release in Cell Culture Supernatant Quantification of E-selectin Cell Surface Protein Expression Fluorescence Staining Statistical Analysis Results Discussion Particle Internalization Particle Cytotoxicity Pro-inflamma…
Structure and composition heterogeneity of a FeAl alloy prepared by one-step synthesis and consolidation processing and their influence on grain size…
2006
Abstract This paper aims to characterize a bulk dense FeAl (47 at.%) alloy synthesized and consolidated by one-step current-activated pressure-assisted processing of nanocrystalline elemental powders. The end-product was analyzed using a combination of scanning (SEM) and transmission electron microscopies (TEM), electron back-scattering diffraction (EBSD) as well as electron probe microanalysis (EPMA). Special attention was paid to verify the grain size (32–89 nm) previously determined by X-ray diffraction peak profile analysis. It has been found that this material displays equiaxed grains (0.8–4 μm in size) and contains limited structural defects like subgrains and dislocations. The EPMA r…
Synthesis of self-assembled mesoporous 3D In2O3 hierarchical micro flowers composed of nanosheets and their electrochemical properties
2018
This report describes the methodology for the fabrication of mesoporous In2O3 microflowers by hydrothermal and calcination procedures in which In(OH)3/In2S3 acts as an intermediate. Both In2O3 and its precursor were analyzed with scanning electron microscopy, energy dispersive X-ray spectrophotometry, transmission electron microscopy and powder X-ray diffraction. BET surface area, pore size and pore volume analyses were also carried out. Electron microscopy images clearly evidence the self-assembly of 2D nanosheets into the micro flower structure. The mechanism of self-assembly and calcination is reported. Electrochemical properties of the synthesized In2O3 micro flowers were studied.
High-resolution transmission electron microscopic investigations of molybdenum thin films on faceted α-Al2O3
2005
Epitaxially grown Mo films on a faceted corundum (α-Al2O3)mplane were investigated by transmission electron microscopy. Low- and high-resolution images were taken from a cross-section specimen cut perpendicular to the facets. It was possible to identify unambiguously the crystallographic orientation of these facets and explain the considerable deviation (∼10°) of the experimental interfacet angle, as measured with atomic force microscopy (AFM), from the expected value. For the first time, proof is given for a smooth \{10\bar{1}1\} facet and a curvy facet with orientation near to \{10\bar{1}\bar{2}\}. Moreover, the three-dimensional epitaxial relationship of an Mo film on a faceted corundumm…
Small-sized granules of biphasic bone substitutes support fast implant bed vascularization
2015
The present study investigated the influence of granule size of 2 biphasic bone substitutes (BoneCeramic® 400-700 μm and 500-1000 μm) on the induction of multinucleated giant cells (MNGCs) and implant bed vascularization in a subcutaneous implantation model in rats. Furthermore, degradation mechanisms and particle phagocytosis of both materials were examined by transmission electron microscopy (TEM). Both granule types induced tissue reactions involving primarily mononuclear cells and only small numbers of MNGCs. Higher numbers of MNGCs were detected in the group with small granules starting on day 30, while higher vascularization was observed only at day 10 in this group. TEM analysis reve…