Loss of Elements From Anhydrously Fixed Pollen During Thin Sectioning

1990 ◽  
Vol 48 (2) ◽  
pp. 330-331
Author(s):  
Hilary R. Skilnyk ◽  
John N.A. Lott
Keyword(s):  
Propylene Oxide ◽  
Pollen Grains ◽  
Water Soluble ◽  
Energy Dispersive ◽  
Cucurbita Maxima ◽  
Cell Cytoplasm ◽  
Ethanol Mixture ◽  
X Ray ◽  
Thin Sectioning ◽  
Tube Cell

Anhydrous fixations are not commonly considered as a means of preparing biological specimens for energy-dispersive x-ray analysis (EDX). Cucurbita maxima and Cucurbita andreana pollen grains were fixed anhydrously because water-soluble materials such as potassium phytate are extracted by aqueous fixatives. Combining anhydrous fixation with anhydrous sectioning techniques demonstrated significant reduction in the extraction of K, Mg and P from globoid particles in the tube cell cytoplasm in pollen.Air-dried Cucurbita maxima and Cucurbita andreana pollen grains were fixed for 4h in 2% paraformaldehyde dissolved in pure glycerol (W/V). Samples were washed for 1.5 h in (1:1) glycerol: 100% ethanol mixture. Dehydration began at 95% ethanol because glycerol is hygroscopic and not completely anhydrous. Infiltration was carried out beginning with propylene oxide followed by a series of Spurr’s resin: propylene oxide mixtures which consisted of 1:3, 1:2, 1:1, 2:1, and 3:1 proportions that were followed by three changes of 100% resin.

Mineral analyses of storage reserves of Cucurbita maxima and Cucurbita andreana pollen

1992 ◽  
Vol 70 (3) ◽  
pp. 491-495 ◽  
Author(s):  
Hilary R. Skilnyk ◽  
John N. A. Lott
Keyword(s):  
Neutron Activation Analysis ◽  
Activation Analysis ◽  
Neutron Activation ◽  
Energy Dispersive ◽  
Specimen Preparation ◽  
Cucurbita Maxima ◽  
X Ray ◽  
Thin Sectioning ◽  
Major Loss ◽  
Storage Reserves

Cucurbita maxima and Cucurbita andreana are so closely related that hybridization is possible. These two species also have been shown to have very different levels of calcium storage in their seeds. Our neutron activation analysis studies have shown that the total amount of P, Ca, K, and Mg in pollen of the two species was similar. Energy dispersive X-ray analysis studies also showed that the composition of electron-dense particles in the tube cells of the two species was similar. Thus the differences in Ca levels in phytate reserves in the seeds of these two Cucurbita species do not appear to be paralleled by differences in mineral reserves in the pollen of the two species. Specimen preparation studies demonstrated that even though elements such as P, K, Mg, and Ca are mostly retained by an anhydrous fixation and embedding protocol, thin-sectioning of such blocks on a water-filled microtome boat resulted in major loss of elements. Key words: pollen, mineral nutrients, energy dispersive X-ray analysis, neutron activation analysis, phytate, Cucurbita.

Changes in the element composition of globoids from Cucurbita maxima and Cucurbita andreana cotyledons during early seedling growth

1996 ◽  
Vol 74 (6) ◽  
pp. 838-847 ◽  
Author(s):  
Penny Beecroft ◽  
John N. A. Lott
Keyword(s):  
Seedling Growth ◽  
Element Composition ◽  
Energy Dispersive ◽  
Mineral Nutrient ◽  
Cucurbita Maxima ◽  
X Ray ◽  
Stages Of Growth ◽  
Early Seedling Growth ◽  
Early Seedling ◽  
Nutrient Conditions

Energy dispersive X-ray analysis was used to study the element composition of globoids from the cotyledons of Cucurbita maxima and Cucurbita andreana seeds and seedlings at various stages of growth. The influence of light and mineral nutrient conditions on changes in globoid composition was also investigated. The element composition of globoids changed markedly during early seedling growth. In both species, regardless of light and mineral nutrient conditions, K decreased markedly, Mg, Ca, Fe, Mn, and Zn generally increased, and P remained relatively constant. There were differences in globoid composition changes between the two species that could be attributed, at least in part, to differences in the Ca content of the mature, dry embryos. In C. andreana, which had a higher initial Ca content, there was a large increase in the Ca content of the globoids during seedling growth and no significant increase in Mn. In C. maxima globoids, there was only a slight increase in Ca, but there was a much larger increase in Fe, Zn, and Mn than occurred in C. andreana. Light conditions alone did not have a significant influence on the changes in globoid composition. Light, in combination with mineral nutrients, resulted in a more rapid degradation of globoids in the later stages of growth. Mineral nutrient conditions affected mostly elements that were initially present in large amounts. There were very large, globoid-like particles present in some later stage samples of both species, from each of the different growth conditions. These particles had element compositions that were consistent with their being composed of phytate. Keywords: Cucurbita, energy dispersive X-ray analysis, globoids, mineral nutrient reserves, large particles.

Ferritin Labeled Antibody Staining of Thin Sections

1969 ◽  
Vol 27 ◽  
pp. 420-421
Author(s):  
J. D. McLean ◽  
S. J. Singer
Keyword(s):  
Biological Material ◽  
Water Soluble ◽  
Thin Sections ◽  
Antibody Staining ◽  
Thin Sectioning ◽  
Ultrathin Sections

The successful application of ferritin labeled antibodies (F-A) to ultrathin sections of biological material has been hampered by two main difficulties. Firstly the normally used procedures for the preparation of material for thin sectioning often result in a loss of antigenicity. Secondly the polymers employed for embedding may non-specifically absorb the F-A. Our earlier use of cross-linked polyampholytes as embedding media partially overcame these problems. However the water-soluble monomers used for this method still extract many lipids from the material.

Microanalysis of precipitates in a ferritic steel

1978 ◽  
Vol 36 (1) ◽  
pp. 618-619
Author(s):  
J.M. Titchmarsh
Keyword(s):  
Ferritic Steel ◽  
Particle Identification ◽  
Energy Dispersive ◽  
Objective Lens ◽  
Ferritic Steels ◽  
Replica Technique ◽  
X Ray ◽  
Large Numbers ◽  
Scanning Transmission ◽  
Made In

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.

Energy Dispersive X-Ray Measurements of thin Metal Foils

1976 ◽  
Vol 34 ◽  
pp. 426-427
Author(s):  
J. Bentley ◽  
E. A. Kenik
Keyword(s):  
Materials Science ◽  
Energy Dispersive Spectrometer ◽  
Thin Foil ◽  
Thin Metal ◽  
Energy Dispersive ◽  
Thin Specimen ◽  
X Ray ◽  
Metal Foils ◽  
Small Probe ◽  
Scanning Transmission

Instruments combining a 100 kV transmission electron microscope (TEM) with scanning transmission (STEM), secondary electron (SEM) and x-ray energy dispersive spectrometer (EDS) attachments to give analytical capabilities are becoming increasingly available and useful. Some typical applications in the field of materials science which make use of the small probe size and thin specimen geometry are the chemical analysis of small precipitates contained within a thin foil and the measurement of chemical concentration profiles near microstructural features such as grain boundaries, point defect clusters, dislocations, or precipitates. Quantitative x-ray analysis of bulk samples using EDS on a conventional SEM is reasonably well established, but much less work has been performed on thin metal foils using the higher accelerating voltages available in TEM based instruments.

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

PHAX-SCAN: Functional integration of a Scanning Electron Microscope and an energy-dispersive x-ray analyser

1989 ◽  
Vol 47 ◽  
pp. 56-57
Author(s):  
Marc H. Peeters ◽  
Max T. Otten
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
Functional Integration ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
High Speed Analysis ◽  
Scanning Electron

Over the past decades, the combination of energy-dispersive analysis of X-rays and scanning electron microscopy has proved to be a powerful tool for fast and reliable elemental characterization of a large variety of specimens. The technique has evolved rapidly from a purely qualitative characterization method to a reliable quantitative way of analysis. In the last 5 years, an increasing need for automation is observed, whereby energy-dispersive analysers control the beam and stage movement of the scanning electron microscope in order to collect digital X-ray images and perform unattended point analysis over multiple locations.The Philips High-speed Analysis of X-rays system (PHAX-Scan) makes use of the high performance dual-processor structure of the EDAX PV9900 analyser and the databus structure of the Philips series 500 scanning electron microscope to provide a highly automated, user-friendly and extremely fast microanalysis system. The software that runs on the hardware described above was specifically designed to provide the ultimate attainable speed on the system.

A morphological and energy-dispersive x-ray spectroscopy (EDS) investigation of separator-grade cellophane

1994 ◽  
Vol 52 ◽  
pp. 430-431
Author(s):  
Michael E. Rock ◽  
Vern Kennedy ◽  
Bhaskar Deodhar ◽  
Thomas G. Stoebe
Keyword(s):  
Extrusion Process ◽  
Morphological Characterization ◽  
Energy Dispersive ◽  
Regenerated Cellulose ◽  
Battery System ◽  
X Ray ◽  
Functional Differences ◽  
Transmission Electron ◽  
Separator Material ◽  
Underwater Target

Cellophane is a composite polymer material, made up of regenerated cellulose (usually derived from wood pulp) which has been chemically transformed into "viscose", then formed into a (1 mil thickness) transparent sheet through an extrusion process. Although primarily produced for the food industry, cellophane's use as a separator material in the silver-zinc secondary battery system has proved to be another important market. We examined 14 samples from five producers of cellophane, which are being evaluated as the separator material for a silver/zinc alkaline battery system in an autonomous underwater target vehicle. Our intent was to identify structural and/or chemical differences between samples which could be related to the functional differences seen in the lifetimes of these various battery separators. The unused cellophane samples were examined by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Cellophane samples were cross sectioned (125-150 nm) using a diamond knife on a RMC MT-6000 ultramicrotome. Sections were examined in a Philips 430-T TEM at 200 kV. Analysis included morphological characterization, and EDS (for chemical composition). EDS was performed using an EDAX windowless detector.

Comparison of high-angle take-off and low-angle take-off EDX detector geometry of the HF-2000 FE-TEM

1993 ◽  
Vol 51 ◽  
pp. 252-253
Author(s):  
Y. Sato ◽  
T. Hashimoto ◽  
M. Ichihashi ◽  
Y. Ueki ◽  
K. Hirose ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Field Emission ◽  
Solid Angle ◽  
Energy Dispersive ◽  
Objective Lens ◽  
X Rays ◽  
High Angle ◽  
X Ray ◽  
Detector Geometry

Analytical TEMs have two variations in x-ray detector geometry, high and low angle take off. The high take off angle is advantageous for accuracy of quantitative analysis, because the x rays are less absorbed when they go through the sample. The low take off angle geometry enables better sensitivity because of larger detector solid angle.Hitachi HF-2000 cold field emission TEM has two versions; high angle take off and low angle take off. The former allows an energy dispersive x-ray detector above the objective lens. The latter allows the detector beside the objective lens. The x-ray take off angle is 68° for the high take off angle with the specimen held at right angles to the beam, and 22° for the low angle take off. The solid angle is 0.037 sr for the high angle take off, and 0.12 sr for the low angle take off, using a 30 mm2 detector.

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