Investigation of thin sections of biological standards by EDX, EELS, and Auger electron spectroscopy

1990 ◽  
Vol 48 (2) ◽  
pp. 184-185
Author(s):  
S. Lehner ◽  
H.E. Bauer ◽  
R. Wurster ◽  
H. Seiler
Keyword(s):  
Processing System ◽  
Beam Current ◽  
Beam Diameter ◽  
Thin Sections ◽  
Biologically Relevant ◽  
Energy Filtering ◽  
Low Viscosity ◽  
Carbon Foils ◽  
Electron Microscopical ◽  
Exchange Membrane

In order to compare different microanalytical techniques commercially available cation exchange membrane SC-1 (Stantech Inc, Palo Alto), was loaded with biologically relevant elements as Na, Mg, K, and Ca, respectively, each to its highest possible concentration, given by the number concentration of exchangeable binding sites (4 % wt. for Ca). Washing in distilled water, dehydration through a graded series of ethanol, infiltration and embedding in Spurr’s low viscosity epoxy resin was followed by thin sectioning. The thin sections (thickness of about 50 nm) were prepared on carbon foils and mounted on electron microscopical finder grids.The samples were analyzed with electron microprobe JXA 50A with transmitted electron device, EDX system TN 5400, and on line operating image processing system SEM-IPS, energy filtering electron microscope CEM 902 with EELS/ESI and Auger spectrometer 545 Perkin Elmer.With EDX, a beam current of some 10-10 A and a beam diameter of about 10 nm, a minimum-detectable mass of 10-20 g Ca seems within reach.

Quantification of cell-surface expressed antigenic sites with 5-nm gold markers: Getting close to biologically relevant data

1989 ◽  
Vol 47 ◽  
pp. 1050-1051
Author(s):  
Etienne de Harven ◽  
Hilary Christensen ◽  
Richard Leung ◽  
Cameron Ackerley
Keyword(s):  
Cell Surface ◽  
Human Peripheral Blood ◽  
Contour Length ◽  
Thin Sections ◽  
Gold Particles ◽  
Biologically Relevant ◽  
Transmission Electron ◽  
Entire Cell ◽  
Electron Imaging ◽  
Cell Contour

The T-derived subset of human peripheral blood normal lymphocytes has been selected as a model system to study the usefulness of 5 nm gold markers for quantification of single epitopes expressed on cell surfaces. The chosen epitopes are parts of the CD3 and CD5 molecules and can be specifically identified by hybridoma produced monoclonal antibodies (MoAbs; LEU-4 and LEU-1; Becton-Dick- inson, Mountain view, CA) . An indirect immunolabeling procedure, with goat anti-murine IgG adsorbed on the surface of 5 nm colloidal gold particles (GAM-G5, Janssen Pharmaceutica, Beerse, Belgium) has been used. Backscattered Electron Imaging (BEI) in a field emission scanning electronmicroscope (SEM) and transmission electron microscopy of thin sections of lymphocytes labeled before plastic embedding, were both used to identify and quantitate gold labeled cell surface sites, Estimating that the thickness of “silver” sections is approximately 60 nm and counting the number of gold particles on the entire cell perimeter, we calculated that, for LEU-4, the number of markers per um2 of cell surface is in the 140-160 range (Fig.l). Cell contour length measurements indicated that the surface of one lymphocyte is approximately 130-160 um2 that of a smooth sphere of identical diameter, reflecting the role of microvilli in expanding the surface area. The total number of gold labeled sites on the surface of one lymphocyte averages, therefore between 20,000 and 24,000 per cell.

The microstructure of functionalized poLyacrylonitrile beads for bioseparations

1990 ◽  
Vol 48 (4) ◽  
pp. 1094-1095
Author(s):  
Eduardo A. Kamenetzky ◽  
David A. Ley
Keyword(s):  
Aqueous Solution ◽  
Affinity Chromatography ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Surface Coverage ◽  
Vacuum Impregnation ◽  
Thin Sections ◽  
Selective Staining ◽  
Low Viscosity ◽  
Diamond Knife

The microstructure of polyacrylonitrile (PAN) beads for affinity chromatography bioseparations was studied by TEM of stained ultramicrotomed thin-sections. Microstructural aspects such as overall pore size distribution, the distribution of pores within the beads, and surface coverage of functionalized beads affect performance properties. Stereological methods are used to quantify the internal structure of these chromatographic supports. Details of the process for making the PAN beads are given elsewhere. TEM specimens were obtained by vacuum impregnation with a low-viscosity epoxy and sectioning with a diamond knife. The beads can be observed unstained. However, different surface functionalities can be made evident by selective staining. Amide surface coverage was studied by staining in vapor of a 0.5.% RuO4 aqueous solution for 1 h. RuO4 does not stain PAN but stains, amongst many others, polymers containing an amide moiety.

Feasibility of Be Analysis For Geologic Materials Using Epma

1997 ◽  
Vol 3 (S2) ◽  
pp. 893-894
Author(s):  
Joseph Evensen ◽  
Gregory P. Meeker
Keyword(s):  
Light Element ◽  
Beam Current ◽  
Operating Conditions ◽  
Beam Diameter ◽  
Element Analysis ◽  
Geologic Materials ◽  
Mineral Phases ◽  
Sample Orientation ◽  
Counting Statistics

Microanalytical techniques for the analysis of beryllium using the electron probe have been evaluated for Be metal, Be-rich silicate minerals, and three Be-rich synthetic silicate glasses. Despite difficulties typical of ultra-light element analysis in geologic materials, quantitative data for Be may be obtainable through careful analytical measurements, determination of optimal operating conditions, and consideration of parameters such as sample orientation and beam-induced migration.Analyses for Be were obtained using a layered synthetic microstructure “crystal” (Mo/B4C) on the JEOL 8900 electron microprobe at the USGS, Denver, Colorado. The optimum accelerating voltage for Be detection was determined to be 8kV (Fig.l). Beryllium analyses in glass and mineral phases were successful using a beam current of 30nA and a 50 μm beam diameter. Due to low count rates, peak counting times of 10 minutes (beryl) and 30 minutes (glass) were required in order to achieve reasonable counting statistics and detection limits.

scholarly journals Chiral Proportions of Nepheline Originating from Low-Viscosity Alkaline Melts. A Pilot Study

Symmetry ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 410
Author(s):  
Ewald Hejl ◽  
Friedrich Finger
Keyword(s):  
Partition Coefficients ◽  
Secondary Nucleation ◽  
Promising Candidate ◽  
Thin Sections ◽  
Low Viscosity ◽  
Low Concentrations ◽  
Three Samples ◽  
Racemic Mixtures ◽  
High Concentrations ◽  
Level Of Significance

Chromatographic interaction between infiltrating solutions of racemic mixtures of enantiomers and enantiomorphic minerals with chiral excess has been proposed as a scenario for the emergence of biomolecular homochirality. Enantiomer separation is supposed to be produced by different partition coefficients of both enantiomers with regard to crystal faces or walls of capillary tubes in the enantiomorphic mineral. Besides quartz, nepheline is the only common magmatic mineral with enantiomorphic symmetry. It crystallizes from SiO2-undersaturated melts with low viscosity and is a promising candidate for chiral enrichment by autocatalytic secondary nucleation. Under liquidus conditions, the dynamic viscosity of silicate melts is mainly a function of polymerization. Melts with low concentrations of SiO2 (<55 wt%) and rather high concentrations of Na2O (>7 wt%) are only slightly polymerized and hence are characterized by low viscosities. Such melts can ascend, intrude or extrude by turbulent flow. Fourteen volcanic and subvolcanic samples from alkaline provinces in Africa and Sweden were chemically analyzed. Polished thin sections containing fresh nepheline phenocrysts were etched with 1% hydrofluoric acid at 20 °C for 15 to 25 min. Nepheline crystals suitable for a statistical evaluation of their etch figures were found in four samples. Crystals with chiral etch figures are mainly not twinned. Their chiral proportions in grain percentages of single crystals are close to parity in three samples. Only one sample shows a slight chiral excess (41.67% L-type vs. 58.33% D-type) but at a low level of significance (15 vs. 21 crystals, respectively).

scholarly journals Evaluation of silicon and germanium retention in rat tissues and diatoms during cell and organelle preparation for electron probe microanalysis.

1975 ◽  
Vol 23 (5) ◽  
pp. 348-358 ◽  
Author(s):  
C W Mehard ◽  
B E Volcani
Keyword(s):  
Rat Liver ◽  
Freeze Substitution ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Rat Tissues ◽  
Cell Organelles ◽  
Thin Sections ◽  
X Ray ◽  
Low Viscosity ◽  
Silicon And Germanium

Chemical, radiochemical and x-ray microanalysis assays were used to define parameters of silicon (Si) retention during preparation og biologic samples (rat liver, spleen, kidney, lung, diatoms and cell organelles) for x-ray microanalysis, Due to its longer half-life 68-Fe was used in some cases to trace SI. Leaching of Si from cells and organelles by the aqueous preparation media was overcome by use of the freeze-substitution process. Cells were treated with 30% glycerol hypertonic sucrose medium to reduce ice damage. Embedment in Spurr's low viscosity epoxy resin medium caused no apparent Si loss. A semiquantitative evaluation showed 0.5 x 10-8 to 0.3 x 10-17 g detectable Si in isolated rat liver mitochondria in thin sections, which is within the instrument's range of detection. This study indicateds that the presence of Si in the mitochondria is not the rsult of contamination.

Protein Storing Vacuoles in Ray Ceils of Willow Wood (Salix Caprea L.)

IAWA Journal ◽  
1988 ◽  
Vol 9 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Jörg J. Sauter ◽  
Silvia Wellenkamp
Keyword(s):  
Dry Weight ◽  
Protein Bodies ◽  
Protein Determination ◽  
Thin Sections ◽  
Salix Caprea ◽  
Coomassie Blue ◽  
Ray Cells ◽  
Dormant Season ◽  
Protein Staining ◽  
Electron Microscopical

Light- and electron-microscopical investigations revealed protein bodies of c. 0.5 to 2.5 µm in diameter in the ray cells of willow wood. They consist of electron-dense aggregatesofvarious structural organisation which are enclosed in small-sized vacuole-like compartrnents. In semi-thin sections these aggregates showed positive protein staining with Ponçeau Red and Coomassie Blue, and enzymatic digestibility with pepsin. Because these protein bodies are found during the dormant season but not during summer, they are believed to be specific sites of protein storage in the ray cells of the wood. This is in accordance with the biochemical protein determination which yielded 6.4 to 8.4 µg mg-1 dry weight in late fall but only 1.2 to 2.0 µg mg-1 dry weight during summer.

Quantitative Analysis Of Bological Specimens by Spectrum-Imaging in the Energy Filtering Transmission Electron Microscope

2000 ◽  
Vol 6 (S2) ◽  
pp. 160-161
Author(s):  
R.D. Leapman ◽  
C.M. Brooks ◽  
N.W. Rizzo ◽  
T.L. Talbot
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Beam Current ◽  
Scanning Transmission Electron Microscope ◽  
Accurate Analysis ◽  
Energy Filtering ◽  
Inverse Power Law ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Spectrum Imaging

Electron energy loss spectrum-imaging (EELSI) in the energy filtering transmission electron microscope (EFTEM) can provide more accurate analysis of elemental distributions than that obtainable by the standard two-window or three-window background subtraction techniques. Spectra containing many channels can be extracted from regions of interest and analyzed using established methods for quantitation. For example, the pre-edge background can be fitted by an inverse power law and subtracted from the post-edge spectrum. EELSI in the EFTEM is often superior to spectrum-imaging in the scanning transmission electron microscope for mapping specimen regions of size greater than 1 μm. This is due the much larger total beam current that is available at the specimen in a fixed-beam microscope relative to a scanned-beam microscope. Our aim here is demonstrate the advantages of such EELSI measurements for analysis of biological specimens. However, we also indicate some potential pitfalls in acquiring elemental maps in the EFTEM, which can be attributed to specimen instabilities during the acquisition.

Intracellular Accumulation of Uranium and Lead in Collembolan (Insect)

1980 ◽  
Vol 38 ◽  
pp. 564-565
Author(s):  
W. Humbert
Keyword(s):  
Heavy Metal ◽  
Beam Current ◽  
Uranyl Acetate ◽  
Intracellular Accumulation ◽  
Cytoplasmic Inclusions ◽  
Thin Sections ◽  
Heavy Metal Poisoning ◽  
X Ray ◽  
Mineral Sequestration ◽  
Metal Poisoning

The midgut epithelium of Collembola contains cytoplasmic inclusions known to be important intracellular sites of mineral sequestration (1). The present study is focused on the role played by these inclusions in cases of heavy metal poisoning. Ultrastructural and X-ray microanalytical studies allowed us to find out different possible mechanisms involved in storage and excretion of these metals. Experiments have been made by rearing the Insects on diet impregnated with the heavy metal (1 % aqueous solutions of uranyl acetate and lead citrate). For each series 100 animals were tested. Animals alive after 2 months were fixed for electron microscopy with glutaraldehyde and osmium tetroxyde. Semi-thin sections were analysed with an electron microprobe analyser CAMECA MS 46 equipped with wavelength dispersive spectrometers (W.D.S.) at 15 KV ; beam current was 40 nA. X-ray microanalysis of thin unstained sections was performed on a “CAMEBAX” microanalyser equipped for transmission with W.D.S. at 50 KV and with a beam current of 100 nA. The use of R.E.T. crystal to detect uranium and lead avoids any misinterpretation (2).

Electron Energy-Loss Spectroscopy (EELS) of Cerium and Uranium Oxidation States

1998 ◽  
Vol 4 (S2) ◽  
pp. 586-587
Author(s):  
Lindsay P. Keller ◽  
John P. Bradley
Keyword(s):  
Oxidation States ◽  
Extensive Literature ◽  
Loss Peak ◽  
Transition Elements ◽  
Edge Structure ◽  
Thin Sections ◽  
Low Viscosity ◽  
Uranium Oxidation ◽  
Powerful Analytical Tool ◽  
Electron Energy Loss

EELS is a powerful analytical tool for exploring the local solid state environment in materials. There is an extensive literature on EELS analysis of the transition elements and light elements, yet few EELS data exist for heavy elements with multiple oxidation states. We report here on EELS studies of oxidation state influences on near-edge structure in cerium and uranium compounds.All materials analyzed for this study were embedded in low viscosity epoxy and TEM specimens prepared using ultramicrotomy. The thin sections (∼50 nm thick) were analyzed using a JEOL 2010 (200kV) TEM operated with a LaB6 filament and equipped with a GAT AN 666 parallel EELS spectrometer. EELS data were collected in image mode at 105X magnification with a collection semi-angle of ∼ 100 milliradians at a dispersion of 0.1 eV/channel. The full width at half maximum of the raw (unprocessed) zero-loss peak was 0.7 eV. Peak positions were calibrated by applying a known voltage to a drift tube.

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