Electron Beam Microanalysis Research Articles

Electron beam microanalysis: several instrumental developments germane to biology.

Electron beam microanalysis: several instrumental developments germane to biology.

Keratopathy Associated With Intracorneal Glass

A progressive nonedematous keratopathy developed in a 36-year-old patient after she was struck in the eye by glass fragments. Biopsy material that was examined by electron microscopy and electron beam microanalysis demonstrated the presence of intracorneal glass fragments, which could not be detected clinically. Retained intracorneal glass, generally thought to be completely inert, can be associated with a chronic keratopathy.

ELECTRON MICROBEAM ANALYSIS AND SCANNING ELECTRON MICROSCOPY OF SOIL-ROOT INTERFACES

ABSTRACT We conducted quantitative point count determinations of phosphorus, potassium, calcium, and magnesium by electron microbeam analysis and scanning electron microscopy of soil-root interfaces with soil-root samples from 30-day-old peanut and soybean plants, grown in Davidson and Cecil soil. Scanning electron micrographs showed undistorted cellular details of the plant roots embedded in the soil mass. Electron microbeam counts revealed that the soil contained lower concentrations of P, K, and Ca than the root tissue. The Mg concentration showed a tendency to be higher in the soil than in the roots. An ascending ion concentration gradient was noticed in the soil from 0.40 to 0.10 mm from the root surface. Nevertheless, a slight decrease in ion concentration was observed 0.05 mm from the root, which was attributed to the presence of a mucilage layer bridging the soil with the root surface. On the basis of a sharp break in element distribution with distance to the root, we estimated the soil rhizosphere to be 0.20 mm thick. Keeping this thin layer of soil saturated was thought to be more beneficial than keeping the bulk of soil saturated with nutrients. Specific accumulation zones of K and Ca were noted in root tissue. Highest concentrations of K and Ca were measured in cortex and epidermis, respectively. Lower levels of K, Ca, and Mg were detected in soybean than in peanut roots, indicating different nutrient requirements between plant species. The results of element counts by electron microbeam analysis in peanut and soybean roots were within ranges of concentrations measured by conventional methods with dry-ashing and atomic absorption spectrophotometry.

ELECTRON MICROBEAM SCANNING OF ELEMENT DISTRIBUTION ZONES IN SOIL RHIZOSPHERE AND PLANT TISSUE

Elemental concentrations and gradients in soil--root interfaces were studied by electron microbeam analysis, used together with a scanning electron microscope. The objective was to observe movement and distribution zones of elements in soil rhizosphere and plant cells. Pine (Pinus taeda), cotton (Gossypium hirsutum L.), and peanut (Arachis hypogeae L.) were grown in the greenhouse, and roots with adhering soil were sampled and prepared by impregnation and fixation techniques. Scanning electron microscopy indicated that the preparation procedures used did not distort the plant tissue and, at the same time, it reduced leaching of elements to a minimum. Cellular details were well preserved, and granular structures of adhering soil were displayed clearly. X-ray distribution images revealed higher concentrations of K, P, Ca, and S in pine-root tissue and the soil rhizosphere than in the soil at a distance 0.2 to 0.3 mm away from the root surface. On the other hand, the x-ray distribution images of Si appeared stronger in the bulk of the soil than in the plant tissue. Magnesium, Mn, and Zn appeared to be evenly distributed over soil and root zones. The highest concentration of K was detected in the cortex, not in the xylem. Calcium was also present,more » in highest concentrations, in peripheral cells of the root nodule of peanut plants. Phosphorus, Mg, Mn, and Zn were not observed to concentrate in specific cells of the root section investigated.« less

Lateral resolution of the electron microbeam analysis

The chemical inhomogenities in modern materials such as fibers, phases and inclusions, often have diameters in the region of one micrometer. Using electron microbeam analysis for the determination of the element concentrations one has to know the smallest possible diameter of such regions for a given accuracy of the quantitative analysis.In th is paper the correction procedure for the quantitative electron microbeam analysis is extended to a spacial problem to determine the smallest possible measurements of a cylindrical particle P of high D (depth resolution) and diameter L (lateral resolution) embeded in a matrix M and which has to be analysed quantitative with the accuracy q. The mathematical accounts lead to the following form of the characteristic x-ray intens ity of the element i of a particle P embeded in the matrix M in relation to the intensity of a standard S

Electron microbeam analysis of calcium distribution in the ciliated protozoan, Spirostomum ambiguum

Electron microprobe analyses of calcium distribution in the ciliated protozoan, Spirostomum ambiguum, indicated several calcium rich sites. One site was an endoplasmic distribution of calcium coincident with phosphorus which corroborates previous findings of hydroxyapatite deposits within Spirostomum. These apatite deposits were distributed throughout the endoplasm, but not within the nuclei or the contractile vacuole. Calcium was also detected within the cortical region. Cortical calcium was in greater concentration in the anterior portion of the organism and decreased towards the posterior end (region containing the contractile vacuole). Phosphorus and potassium were also detected as gradients from the anterior end, whereas magnesium was detected in the same density throughout the cortical region. Line scans of cortical regions suggested (1) distributions of calcium within mitochondria and/or vesicles, and (2) calcium associated with bundles of microfilaments.

Detection of thin surface films by electron beam microanalysis. A comparison between wavelength-dispersive and energy-dispersive microprobes

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Physical Aspects of Electron Microscopy and Microbeam Analysis

Physical Aspects of Electron Microscopy and Microbeam Analysis

Electron beam microanalysis of electrochemical attack on thin film nickel-chromium resistors (Technical rept.) : J. J. Bart. Rome Air Development Center (Oct. 1973). RADC-TR-73-220

Electron beam microanalysis of electrochemical attack on thin film nickel-chromium resistors (Technical rept.) : J. J. Bart. Rome Air Development Center (Oct. 1973). RADC-TR-73-220

Annealing of cylindrical Ni-Fe films

The effect of annealing on the microstructure of cylindrical electrodeposited 81-percent Ni, 19-percent Fe films was studied with the electron microscope. The films were deposited onto 5-mil Be-Cu wires having either Au or Cu intermediate layers. The annealing was performed on both free-standing films and on films still attached to the substrate. The initial change in the free-standing films was a rapid recrystallization. After the whole film had recrystallized, normal grain growth was observed. There is evidence that the driving force for the annealing is provided by stresses present in the films. Films annealed while attached to a Au-Be-Cu substrate did not exhibit recrystallization or grain growth, and the electron microscope studies showed that the Ni-Fe grains were pinned by Be-Au which diffuses into the grain boundaries but does not alloy with the Ni-Fe. The films which were annealed while attached to a Cu-Be-Cu substrate behaved essentially like free-standing films. Electron beam microanalysis and electron diffraction studies revealed that Be-Cu diffuses into the Ni-Fe grain boundaries and then alloys with the Ni-Fe. Recrystallization of the alloy can then take place freely.

The Differences between Meteoritic and Volcanic Spherules.

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Differences between Meteoritic and Volcanic Spherules. Wright, F. W. ; Hodge, P. W. ; Franklin, F. A. Abstract We have acquired dust deposits from five Pacific Coast extinct volcanoes and from three recently or currently active volcanoes in order to search for and analyze microscopic volcanic spberules that might possibly be similar to the meteoritic spherules found in polar ice deposits and at other remote sites. Electron-beam microanalysis shows a difference in composition for the volcanic particles and for the arctic ice spherules. The majority of the latter are similar to magnetite in composition, with 50-75% Fe (by weight), no Al, and little or no Si, while the volcanic spherules show a composition more like 20-30% Fe in the mean, 8% Al, and 19% Si. In addition we find the concentration of spherules, relative to irregular particles, to be very much higher for the arctic samples than for the volcanic samples. These results support our conclusion that a volcanic origin is impossible for the majority of the meteoritic spherules recovered in ice deposits and in other remote regions. For a third possible criterion, we have measured the densities of a few individual spherules of both types. Publication: The Astronomical Journal Pub Date: June 1965 DOI: 10.1086/109742 Bibcode: 1965AJ.....70..334W full text sources ADS |

Electron Beam Microanalysis of Germanium Tunnel Diodes [Letter to the Editor

The purpose of this Letter is to describe the results of electron beam microanalysis of impurities in germanium tunnel diodes. The apparent possibilities and limits of applicability for tunnel diode technology will be discussed.

Electron beam micro-analysis of some plutonium-iron alloys

A simple method, which involves first coating the specimen with a thin plastic film, permits the examination of plutonium in an unmodified commerciallymade electron beam micro-analysis instrument, without incorporating it in a glove box. No contamination of the apparatus with radioactivity was experienced. The results obtained in this way concerning the micro-distribution of elements in a series of plutoniumiron alloys are presented and discussed.