Electron Energy Loss Spectroscopy Imaging Research Articles

Developmental regulation of pectic epitopes during potato tuberisation

We show, by immunogold labelling, that potato (Solanum tuberosum L. cv Karnico) pectic epitopes are developmentally regulated within regions of the stolon, in addition to showing tissue-specific differences in abundance and localisation. The (1-->4)-beta-D-galactan and (1-->5)-alpha-arabinan epitopes demarcate two distinct zones within stolons; galactans are enriched in primary walls of elongating cells proximal to the stolon hook, whilst arabinans predominate in younger cells distal to the hook. Low-methoxyl homogalacturonan epitopes are concentrated in the middle lamella and show a proximo-distal gradient in stolons similar to that of galactans, whilst high-methoxyl homogalacturonan is uniformly abundant. Calcium pectate is restricted to the middle lamella at cell corners and pit fields. Calcium-binding sites are uniformly present in stolon cell walls, but their total density is reduced and they become localised to a few cell corners in mature tubers, as determined by image-electron energy loss spectroscopy. During the transition from elongation growth to isodiametric expansion during tuberisation of the stolon hook, there were no detectable changes in pectic epitope abundance or localisation. As tubers matured, all epitopes increased in abundance in parenchymal cell walls, except for calcium pectate. We conclude that potentially significant changes in pectic composition occur as young cells distal to the stolon hook move into the zone of cell elongation proximal to the hook.

3d Reconstruction of Sub-Nm Beam Profiles in STEM

Abstract Introduction:Atomically resolved chemical analysis using techniques such as electron energy loss spectroscopy and annular dark field imaging relies on the ability to form a well-characterised sub-nm electron beam in a FEGTEM/STEM [1-2]. to understand EELS+EDX-signal formation upon propagation of a sub-nm beam through materials we first have to assess precisely the beam intensity distribution in vacuum and find conditions for the best obtainable resolution. Experimental Details:Modern TEM/STEM instruments combine features of both imaging and scanning technology. The beam forming capability approaches closely that for dedicated STEMs, while CCD recording devices allow us to measure the beam profile by direct imaging at magnifications up to 1.5 M. The recording of a “z-section” series through the 3D intensity distribution of the cross-over can therefore be realised by recording of a “condenser focal series”.

The Spatial Distribution of Water in Soap

Soap bars can be viewed as pseudo-binary two-phase composites consisting of solid particulate suspended in water-enriched medium. Understanding the size and the distribution of the two phases in a bar is of interest to cosmetic industry. Electron Energy Loss Spectroscopy (EELS) combined with Scanning Transmission Electron Microscope (STEM) has been used to perform water mapping in certain biological systems. Here we report preliminary analysis of soap-water matrix in a soap bar by employing EELS and spectrum imaging techniques.Thin slices of soap bars containing 13% water (as measured using Karl Fischer titrator) were frozen using a Leica high-pressure freezer (EM PACT). 200 nm thick cryo-sections were cut at -160°C. The frozen sections were cryo-transferred at -170°C to a Philips CM20 FEG electron microscope equipped with the Gatan CCD spectrometer ENFINA interfaced to an Emispec Vision system for digital control and data acquisition.

Altered middle lamella homogalacturonan and disrupted deposition of (1-->5)-alpha-L-arabinan in the pericarp of Cnr, a ripening mutant of tomato.

Cnr (colorless non-ripening) is a pleiotropic tomato (Lycopersicon esculentum) fruit ripening mutant with altered tissue properties including weaker cell-to-cell contacts in the pericarp (A.J. Thompson, M. Tor, C.S. Barry, J. Vrebalov, C. Orfila, M.C. Jarvis, J.J. Giovannoni, D. Grierson, G.B. Seymour [1999] Plant Physiol 120: 383-390). Whereas the genetic basis of the Cnr mutation is being identified by molecular analyses, here we report the identification of cell biological factors underlying the Cnr texture phenotype. In comparison with wild type, ripe-stage Cnr fruits have stronger, non-swollen cell walls (CW) throughout the pericarp and extensive intercellular space in the inner pericarp. Using electron energy loss spectroscopy imaging of calcium-binding capacity and anti-homogalacturonan (HG) antibody probes (PAM1 and JIM5) we demonstrate that maturation processes involving middle lamella HG are altered in Cnr fruit, resulting in the absence or a low level of HG-/calcium-based cell adhesion. We also demonstrate that the deposition of (1-->5)-alpha-L-arabinan is disrupted in Cnr pericarp CW and that this disruption occurs prior to fruit ripening. The relationship between the disruption of (1-->5)-alpha-L-arabinan deposition in pericarp CW and the Cnr phenotype is discussed.

Nanocrystalline Domain Identification in Gold Films, by Backscattered Electron Imaging and Energy-Filtered Transmission Electron Microscopy

Gold nanocrystallites dispersed in an inhomogeneous gold matrix are detected by high-resolution scanning electron microscopy using a field emission source and backscattered electron detection in the composition mode, as well as by energy-filtered transmission electron microscopy in the plasmon energy region. The identity of the nanocrystalline domains was established by observing the same evaporated gold film samples but using bright-field, dark-field, electron diffractogram, and electron energy loss spectroscopy images in the transmission electron microscope. Comparison of these images shows that backscattered electron and plasmon energy detection can be used to identify crystalline domains in an otherwise chemically uniform sample.

Opportunities and pitfalls in characterisation of nanoscale features

Thermally assisted field emission gun TEM (FEGTEM), with associated electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) is used to characterise nanoscale features in technologically important materials. The exceptionally high spatial and temporal coherence of the FEG source allows high resolution image information down to 0.1 nm to be routinely imaged, but the complexity of the atomic contrast makes interpretation of interface structure more difficult than with LaB6 sources. A spatial resolution of 0.9 nm for through thickness features and 2 nm for embedded particles is demonstrated for ESI, illustrating the remarkable sensitivity of this technique. The energy resolution of the FEG source (0.65 eV) is sufficient to resolve the fine near edge structure in EELS spectra to allow bonding information to be obtained with a spatial resolution of 1 nm or possibly better. X-ray energy dispersive spectroscopy can be performed on a similar scale, sufficiently small to identify submonolayer segregates at interfaces. The limitations of each technique are discussed in relation to the critical microstructural information required for each material investigated.

New Approaches for Energy Filtered Imaging and EELS Analysis

Abstract Electron energy-loss spectroscopy imaging is now becoming an established and indispensable tool in high-resolution materials characterization. Whether the imaging approach is based on post column filters attached to a conventional transmission electron microscope (TEM) or on parallel spectrometers on a scanning (field emission) TEM, energy filtered (EF) microscopy is having a significant impact in materials science (e.g. Ref. 1). Elemental mapping, however, is not the only imaging tool accessible with EF microscopy. EELS images and spectra are often only part of the data that is obtained when samples are characterized in an analytical TEM. Complementary information is also obtained from EDS spectra which are often analyzed independently from the EELS data and from EELS near edge structures. When the EELS fine structure is altered due to changes in chemical state of the probed atoms, additional information is accessible and can potentially be used in novel methods of image acquisition.

Electron Energy Loss Spectroscopy and Annular Dark Field Imaging at a Nanometer Resolution in a Scanning Transmission Electron Microscope

The basics of electron energy loss spectroscopy (EELS) performed in the context of a scanning transmission electron microscope are described. This includes instrumentation, information contained in an EELS spectrum, data acquisition and processing, and some illustrations by a few examples.

Analysis of the Atomic Scale Oxygen Vacancy Ordering by EELS and Z-Contrast Imaging

Abstract Perovskite-type oxides with high electronic and ionic conductivity are very promising materials for use as dense ceramic membranes for oxygen separation. For the successful implementation of practical ceramic membranes, a full understanding of the parameters controlling the degree of non-stoichiometry, i.e. the defect chemistry is essential. A combination of Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) can be used to directly image crystal and defect structures and the effect of the structures on the local electronic properties (i.e. oxygen coordination and cation valence). Here the defect chemistry in SrCoO3-δ before and after a reduction treatment at high temperatures is investigated in the JEOL 201 OF STEM. This material is known to exist in a wide a variety of phases with different crystal structures, compositions and valence states of cobalt, and can be highly oxygen deficient.

Atomic Scale Characterization of Oxygen-Deficient Ceramic Membranes by EELS and Z-Contrast Imaging

Abstract The Perovskite structured ceramic (Lax,Sr1-x)(Fey,Cr1-y)O3-δ being developed for applications in oxygen transporting membranes. The permeability of this material is limited by the number of free ions, point-defects (oxygen vacancies) and electrons in the bulk. As any ordering of these unbound particles will restrict their mobility one key issue for controlling the membrane efficiency is the formation of ordered oxygen vacancies. In particular it is very likely, that at elevated temperatures ordered micro-domains progressively grow and asymptotically reach a stable equilibrium concentration. This is consistent with the observations of Kruidhof that below a specific order-disorder transition temperature equilibrium times of 30-40 h are required to attain steady-state conditions, irrespective of the thermal history of the sample. We investigate the formation of ordered vacancies in (Lax,Sr1-x)(Fey,Cr1-y)O3-δ by atomic resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) using a 200 keV STEM/TEM JEOL2010L with a post column Gatan Image Filter (GIF).

Enhancement of perpendicular and parallel giant magnetoresistance with the number of bilayers in Fe/Cr superlattices

We have correlated a detailed quantitative structural analysis by x-ray diffraction, transmission electron microscopy, and high spatial resolution electron energy-loss spectroscopy imaging, with the magnetization and anisotropic magnetotransport properties in sputtered Fe/Cr superlattices. To accomplish this, we developed a technique for magnetotransport measurements in metallic superlattices with the current perpendicular to the plane of the layers (CPP). Using microfabrication techniques, we have fabricated microstructured Fe/Cr pillars embedded in ${\mathrm{SiO}}_{2}$ and interconnected with Nb electrodes. Because of the uniform current distribution in the Nb electrodes and the minimization of the superlattice-electrode contact resistance, the method allows a simple and independent measurement of the superlattice resistance and giant magnetoresistance (GMR). Structural and magnetic characterization of $[\mathrm{Fe}\mathrm{}(3\mathrm{}\mathrm{n}\mathrm{m})/\mathrm{C}\mathrm{r}\mathrm{}(1.2\mathrm{}\mathrm{n}\mathrm{m}){]}_{N}$ superlattices (where N is the number of repetitions) indicate that the roughness is correlated and increases cumulatively through the superlattice stack with no significant change in the antiferromagnetic coupling. Both the current in-plane and CPP GMR increase with N as the roughness increases.

Structural and electronic characterization of a dissociated60°dislocation in GeSi

A dissociated $60\ifmmode^\circ\else\textdegree\fi{}$ misfit dislocation at the substrate interface of a ${\mathrm{S}\mathrm{i}/\mathrm{G}\mathrm{e}}_{x}{\mathrm{Si}}_{(1\ensuremath{-}x)}$ heterojunction has been examined using electron energy loss spectroscopy and annular dark field imaging. New spectra are obtained at the intrinsic stacking fault, at the dislocation cores, and in the strained regions on either side of the stacking fault. In-gap states are verified at the partial dislocation cores. Images resemble accepted structures except at the 90\ifmmode^\circ\else\textdegree\fi{} partial dislocation. Model structures for the object are considered to try to reconcile the imaging and spectral results.

Coiled structure of eccentric coaxial nanocable made of amorphous boron and silicon oxide

Exotic nanocable with coiled structure has been found in soot obtained by a reactive laser ablation as a byproduct of the formerly reported coaxial nanocables [Y. Zhang, K. Suenaga, C. Colliex, and S. Iijima, Science 281, 973 (1998)]. Electron energy-loss spectroscopic imaging has revealed the coaxial structure made of amorphous boron and silicon dioxide with amorphous carbon sheath. We infer that the coiled structure is attributed to a difference in the growth rate between amorphous boron and silicon dioxide that are found to comprise eccentric coaxial nanocable.

Methods for analysis of Ca 2+/H + antiport activity in synaptic vesicles isolated from sheep brain cortex

The involvement of Ca 2+-storage organelles in the modulation of synaptic transmission is well-established [M.K. Bennett, Ca 2+ and the regulation of neurotransmitter secretion, Curr. Opin. Neurobiol. 7 (1997) 316–322 [1]; M.J. Berridge, Neuronal calcium signaling, Neuron 21 (1998) 13–26 [2]; Ph. Fossier, L. Tauc, G. Baux, Calcium transients and neurotransmitter release at an identified synapse, Trends Neurosci. 22 (1999) 161–166 [7]]. Various Ca 2+ sequestering reservoirs (mitochondria, endoplasmic reticulum and synaptic vesicles) have been reported at the level of brain nerve terminals [P. Kostyuk, A. Verkhratsky, Calcium stores in neurons and glia, Neuroscience 63 (1994) 381–404 [18]; V. Mizuhira, H. Hasegawa, Microwave fixation and localization of calcium in synaptic terminals using X-ray microanalysis and electron energy loss spectroscopy imaging, Brain Res. Bull. 43 (1997) 53–58 [21]; A. Parducz, Y. Dunant, Transient increase of calcium in synaptic vesicles after stimulation, Neuroscience 52 (1993) 27–33 [23]; O.H. Petersen, Can Ca 2+ be released from secretory granules or synaptic vesicles?, Trends Neurosci. 19 (1996) 411–413 [24]]. However, the knowledge of the specific contribution of each compartment for spatial and temporal control of the cytoplasmic Ca 2+ concentration requires detailed characterization of the Ca 2+ uptake and Ca 2+ release mechanisms by the distinct intracellular stores. In this work, we described rapid and simple experimental procedures for analysis of a Ca 2+/H + antiport system that transport Ca 2+ into synaptic vesicles at expenses of the energy of a ΔpH generated either by activity of the proton pump or by a pH jumping of the vesicles passively loaded with protons. This secondary active Ca 2+ transport system requires high Ca 2+ concentrations (>100 μM) for activation, it is dependent on the chemical component (ΔpH) of the proton electrochemical gradient across the synaptic vesicle membrane and its selectivity is essentially determined by the size of the transported cation [P.P. Gonçalves, S.M. Meireles, C. Gravato, M.G.P. Vale, Ca 2+–H +-Antiport activity in synaptic vesicles isolated from sheep brain cortex, Neurosci. Lett. 247 (1998) 87–90 [10]; P.P. Gonçalves, S.M. Meireles, P. Neves, M.G.P. Vale, Ionic selectivity of the Ca 2+/H + antiport in synaptic vesicles of sheep brain cortex, Mol. Brain Res. 67 (1999) 283–291 [11]; P.P. Gonçalves, S.M. Meireles, P. Neves, M.G.P. Vale, Synaptic vesicle Ca 2+/H + antiport: dependence on the proton electrochemical gradient, Mol. Brain Res. 71 (1999) 178–184 [12]]. The protocols described here allow to ascertain the characteristics of the Ca 2+/H + antiport in synaptic vesicles and, therefore, may be useful for clarification of the physiological role of synaptic vesicles in fast buffering of Ca 2+ at various sites of the neurotransmission machinery.Theme: Excitable membranes and synaptic transmission.Topic: Presynaptic mechanisms.

Distribution of iron oxide nanoparticles in rat lymph nodes studied using electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI).

Superparamagnetic iron nanoparticles have been developed as contrast agents for magnetic resonance lymphography. The kinetics of uptake of these particles has not yet been accurately determined. We have therefore monitored the distribution of individual iron particles (ferumoxtran, AMI-227, Sinerem) in rat lymph nodes 1.5, 3, 6, 12, and 24 hours after i.v. injection (two rats per time point). The ultrastructural distribution of the iron was determined by energy-filtered transmission electron microscopy (EFTEM). This method allows the identification of elements using element-specific energy-loss electrons. Iron was identified by the Fe-L(2,3) edge (EELS), and iron maps were obtained using iron-specific electrons for imaging (ESI). The background was calculated by simplex optimization (EELS) and by the two-window method (ESI). Ferumoxtran particles were regularly observed at the periphery of the lymph nodes but not in their centers. Isolated iron particles were seen extracellularly within lymph vessels and, 3 hours after injection, as small dots in phagocytic cells. Numerous dense clusters appeared within the cells at later times (6 and 12 hours after injection). These results suggest that the contrast agent moves rapidly across the capillary wall to the lymph and is then taken up by phagocytic cells. J. Magn. Reson. Imaging 2000;12:505-509.

Nanoscale structure and chemistry of Al0.49In0.51P thermal oxide

In this letter, the nanoscale structure and chemistry of the III–V thermal oxide formed from Al0.49In0.51P is described. Transmission electron microscopy studies have shown that the oxide is an amorphous compound, which occupies greater volume than the original unoxidized crystalline Al0.49In0.51P layer, and which contains O, Al, In, and P (i.e., none of the species are completely desorbed during the oxidation reaction). Electron energy loss spectroscopy and energy spectroscopic imaging have shown specifically that the oxidation products include Al2O3 and In2O3 and P, either as an oxide or in some other amorphous compound.

Characterization Of SiOx Smoke Particles by Electron Energy Loss Spectroscopy and Energy-Filtering Imaging

Combustion synthesis has led to many advances in materials science, in part via the synthesis of powders consisting of particles of nanometer dimensions. Particle morphology is a key concern regarding the powders produced, but also of comparable importance is particle composition. Electron energy loss spectroscopy (EELS) and energy-filtering imaging (EFI) can be used to interrogate the gas-phase combustion synthesis environment for elemental particle composition information. Once established, this diagnostic approach can be used to address control of particle composition and other issues associated with particle formation and growth in flames. The evolution of the particle morphology in a laboratory scale combustion synthesis facility can be examined by passing TEM grids directly through the combustion synthesis flame at various heights above the burner surface, as shown in Fig. la. For the current work, SiOx particle samples are obtained from a SilL/^/FL/Ar flame using a rapid probe insertion technique.

High resolution mapping of total calcium in osteoblasts by electron energy loss spectroscopy and electron spectroscopic imaging

Biology of the CellVolume 91, Issue 3 p. 276-276 High resolution mapping of total calcium in osteoblasts by electron energy loss spectroscopy and electron spectroscopic imaging C. Bordat, C. Bordat Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this authorO. Bouet, O. Bouet Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this authorP. Gounon, P. Gounon Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this authorG. Cournot, G. Cournot Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this author C. Bordat, C. Bordat Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this authorO. Bouet, O. Bouet Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this authorP. Gounon, P. Gounon Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this authorG. Cournot, G. Cournot Institut de Bioiogie Structurale JP Ebel; 41, rue Jules Horowitz; 38027 Grenoble cedex 1, FranceSearch for more papers by this author First published: 01 February 2012 https://doi.org/10.1016/S0248-4900(99)90117-XAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume91, Issue3June 1999Pages 276-276 RelatedInformation

Electron-energy-loss spectroscopic imaging of calcium and nitrogen in the cell walls of apple fruits

Changes in texture are an integral part of ripening in most fleshy fruits and these changes are thought to be determined, primarily, by alterations in cell wall structure. Electron energy loss spectroscopy (EELS) imaging was used to obtain quantitative information on the levels of calcium and nitrogen in the cell walls of apple (Malus domestica Borkh. cv. Cox's Orange Pippin) fruits. Samples of fruit cortex were prepared for EELS by high-pressure freezing and molecular distillation drying to minimize loss and redistribution of soluble cell wall components such as calcium. The EELS imaging successfully resolved calcium and nitrogen levels in the middle lamella and primary cell wall. When the elemental compositions of the cell walls of Cox's apples from two sites in the UK were compared at harvest or after 6 months storage, the orchard which always produced consistently firmer fruit had significantly lower levels of cell wall calcium and higher levels of cell wall nitrogen. This result was unexpected since firm texture in apples and other fruits has been commonly associated with elevated levels of fruit calcium. The nitrogen-rich material in the sections used for EELS was insoluble in acidified methanol, indicating that it represented a high-molecular-weight component in the cell wall. Furthermore, total tissue hydroxyproline levels were greatest in material with elevated cell wall nitrogen, suggesting enhanced levels of wall structural proteins in the tissue. These data indicate a correlation between increased amounts of cell wall nitrogen and firm fruit texture. The possible role of cell wall proteins in determining the textural properties of fruit tissue is discussed.

Quantification of total calcium in terminal cisternae of skinned muscle fibers by imaging electron energy-loss spectroscopy.

Skinned muscle fibers are ideal model preparations for the investigation of Ca2+ -regulatory mechanisms. Their internal ionic milieu can be easily controlled and distinct physiological states are well defined. We have measured the total Ca content in the terminal cisternae of such preparations using imaging electron energy-loss spectroscopy (Image-EELS) as a new approach for quantification of sub-cellular element distributions. Murine muscle fibers submitted to a standardized calcium-loading procedure were cryo-fixed with a combined solution exchanger/plunge freezing device. Energy-filtered image series were recorded from ultrathin freeze-dried cryosections of samples immobilized in either relaxed or caffeine-contracted state. From these image series, electron energy-loss spectra were extracted by digital image-processing and quantitatively processed by multiple-least-squares-fitting with reference spectra. The calculated fit coefficients were converted to Ca-concentrations by a calibration obtained from Ca-standards. Total Ca-contents in the terminal cisternae of skinned skeletal muscle fibers decreased upon caffeine-induced Ca-release from 123+/-159 (+/-11) to 73+/-102 (+/-8) mmol/kg d.w. (weighted mean +/- SD (+/-SEM)).