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Results for “Electron Probe Microanalysis”

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PubMed1984

Scanning electron microscopic and electron microprobe X-ray analysis of cortical bone of fluoride-treated rabbits.

Sodium fluoride was administered to rabbits through the intragastric route at the rate of 10 mg/kg every day for a period of 8 months. Cortical bone from the diphyseal region of the femur was studied morphologically with a scanning electron microscope, and significant structural changes in collagen fiber were observed in the fluoride-treated animals as compared to normal bone. Similar bone samples were assessed physically for their CaK alpha/PK alpha ratio by electron microprobe x-ray analysis, and chemically for their calcium and phosphorus content. The bone from the rabbits to which sodium fluoride had been administered showed a higher Ca/P ratio than that from untreated control animals by both of the methods of assessment. Possible explanations for the increased Ca/P ratio in relation to the observed structural changes are discussed.

Animals↗
PubMed1983

Applications of energy filtered imaging in biology.

We describe the use of a magnetic sector spectrometer positioned below the projection chamber of an electron microscope for energy filtered transmission imaging. The spectrometer used has circular pole face edges and is corrected for second order aberrations. A round EM lens is placed after the sector to form a real image of the virtual achromatic image produced by the spectrometer. A slit placed in the dispersion plane allows the passage of electrons in a selected energy range. The filtered image is projected onto a transmission phosphor and acquired with a silicon intensified TV camera and stored in digital form on computer disk. Filtered images are taken at two energies, one immediately preceding (pre-edge) and one on the characteristic energy loss (edge). To obtain images showing the distribution of elements, background subtraction is performed by either subtraction or division of edge and pre-edge images. The optical properties of the imaging system are described and the results are illustrated by energy filtered images of single ferritin molecules (Fe M2,3 and C k), the phosphorus distribution in ribosomes (PL2,3) and the localization of calcium in muscle (Ca L2, 3). The major advantage of the system, compared to other energy filtered imaging methods, is that it can be readily adapted to existing high vacuum microscopes without the necessity of modifying the column to insert a spectrometer.

Animals↗
PubMed1983

Assembly and reliability of an X-ray microanalyser system with a possibility for independent mass measurement.

A new X-ray microanalyser assembly is described, the main parts of which are a JEOL 100 B transmission electron microscope, a JEOL ASID I scanning attachment, an EDAX 183 B semiconductor detector and a KFKI ICA 70 4k multichannel analyser. By using this equipment, qualitative analysis, equivalent to the original EDAX version, can be performed. Furthermore it is possible to visualize simultaneously the spatial distribution of two or more elements in the sample. The mass of the excited volume of the sample can be determined, independently of the X-ray measurements, by using the electron detector of the scanning attachment. The reproducibility of such measurements is demonstrated and a calibration curve is given. By recording the excited mass of the sample during the X-ray analysis, the damage caused by the exciting electron beam was also examined.

Electron Probe Microanalysis↗
PubMed1982

Changes in calcium phosphate on bone surfaces and in lining cells after the administration of parathyroid hormone or calcitonin.

Small doses of parathyroid hormone and calcitonin were injected into thyroparathyroidectomized newborn rats to investigate the histological and chemical changes in bone surfaces and in mitochondrial granules of bone lining cells. Nondecalcified tissue specimens were observed under transmission electron microscope, electron probe X-ray microanalyzer, and microdiffraction after "freeze substitution" preparation of tibia shafts. Amorphous calcium phosphate, which appears as clusters and globules by this "freeze substitution" preparation, appears on the bone surfaces in a short time after the administration of a small dose of calcitonin. The Ca:PO4 ratio in the mitochondria of bone lining cells rises slightly with a small dose of parathyroid hormone and is reduced with a small dose of calcitonin. These data support the postulate that both parathyroid hormone and calcitonin act directly on bone lining cells in the process of influencing calcium concentrations of blood and temporarily storing calcium at bone surfaces.

Animals↗
PubMed1993

Aluminium in rat cerebellar neural cultures.

A systematic microchemical analysis of unstained and uncoated neurone cultures was performed with synchrotron radiation photoemission spectromicroscopy after exposure to an aluminium solution. Clear evidence was found for localized aluminium uptake in a few cells. Their possible identification based on morphology is discussed.

Aluminum↗
PubMedDate not supplied

Interfacial reactions of cast titanium with mold materials.

PURPOSE: Dental casting requires replication of complex shapes with high fidelity. To achieve this objective, the problem of scale formation on titanium dental castings must be overcome. Scaling occurs readily at high temperatures because of the high reactivity of molten titanium with investment materials. The purpose of this study was to examine the effectiveness of using stable oxide coatings on the mold surface to reduce the interfacial reactions. MATERIALS AND METHODS: A traditional phosphate-bonded dental investment, a commercial titanium investment, and an experimental oxide coating were used for the molds. Pure titanium samples were cast, divested, and prepared for scanning electron microscopic and energy dispersive x-ray spectroscopic analyses. RESULTS: Layers of 7- to 10-micron-thick scale were formed on titanium castings during reaction with traditional mold materials. Interface reaction was reduced between the molten titanium and the investment material when yttrium oxide or zirconium oxide coatings were applied to the mold before casting. CONCLUSION: Less titanium-mold interfacial reactions occurred when protective coatings were used as diffusion barriers for titanium casting. Y2O3-coating oxide particles applied without binder were entrapped in the cast titanium surface layer. Further study of a binder system for Y2O3 coating is needed.

Dental Casting Investment↗
PubMed2002

Airborne particles in the Miyagi Museum of Art in Sendai, Japan, studied by electron probe X-ray microanalysis and energy dispersive X-ray fluorescence analysis.

The presented work provides baseline data on the existing airborne conditions in the Miyagi Museum of Art in Sendai, Japan, during the summer of 2000. The chemical composition, size and indoor and outdoor origin of the suspended particulate matter were identified using a number of advanced X-ray techniques, such as Electron Probe X-Ray Microanalysis (EPXMA) and Energy Dispersive X-Ray Fluorescence Analysis (EDXRF). Our results, to the best of our knowledge, represent the first detailed study of the chemical nature of the indoor particulate matter in a Japanese museum and, as such, may contribute to future improvements of the air quality inside museums and to the lasting conservation of works of art.

Journal Article↗
PubMed1991

X-ray microanalysis of cell nuclei.

The principal component analysis, a multivariate statistical analysis of data, has been used to process X-ray microanalytical data from cell nuclei. Sixty-seven measurements from different areas of chromatin, nucleoli of rat follicular cells, and nucleoli of rat oocyte cells in their antral stage have been studied. The variables are the X-ray characteristic signals for P, S, Al, Fe, Cu, and Zn. This method demonstrates four distinct groups, the chromatin area, which is associated with a higher concentration of P; the compact mass of oocyte nucleolus which possesses the highest content in S, Al, and Zn, and two groups of nucleolar areas. The fibrillar component is richer in S, Al, and Zn than the granular component. The high degree of correlation between these three elements proves the chemical affinity of metals for the proteins (S being the signature for proteins). Cryoembedding in Lowicryl resin at even lower temperatures (213 degrees K in K11M) after quick cryofixation and cryosubstitution in the absence of chemical fixatives gives good ultrastructural preservation and the possibility of simultaneously performing X-ray microanalysis and immunocytochemistry.

Animals↗
PubMed1984

Three-dimensional architecture of altered dermal elastic fibers in pseudoxanthoma elasticum: scanning electron microscopic studies.

The three-dimensional architecture of the altered dermal elastic fibers of patients with pseudoxanthoma elasticum has been demonstrated using a scanning electron microscope. Each of the altered elastic fibers could be divided into three parts: (i) a normal-looking, slender part which is composed of thinner fibrils, (ii) a thickened, tortuous part covered with an amorphous substance, and (iii) a markedly damaged part where calcium is exposed to the surface of the fibers. The presence of calcium and phosphorus in the altered elastic fibers has been proved by an electron x-ray microanalysis.

Calcium↗
PubMed1999

Electron-probe X-ray Microanalysis of Magnesium and Sodium Ion Content in Vascular Smooth Muscle Cells from Spontaneously Hypertensive and Normotensive Rats.

Whereas in blood cells decreased magnesium concentrations and increased sodium concentrations in essential hypertension have often been described, only sparse data exist on cellular magnesium or sodium content in vascular smooth muscle cells. Therefore, in aortic smooth muscle cells from seven spontaneously hypertensive rats (SHR) of the Münster strain and seven normotensive Wistar-Kyoto rats (WKY), the intracellular magnesium and sodium content were measured by electron-probe X-ray microanalysis. Measurements were performed in aortic cryosections 3 µm thick. The magnesium ion content was 0.93 +/- 0.17 g/kg dry weight in SHR vs 1.14 +/- 0.12 g/kg dry weight in WKY (p < 0.05). Vascular smooth muscle sodium ion content was measured at 6.85 +/- 0.59 g/kg dry weight in WKY and 12.47 +/- 1.62 g/kg dry weight in SHR (p < 0.05). In conclusion, aortic smooth muscle cells from SHR are characterized by a markedly lowered intracellular magnesium ion content and increased sodium ion concentrations compared with normotensive cells. The results may be due to genetically determined disturbances in transmembrane magnesium and sodium ion transport. Cellular magnesium and sodium handling may be disturbed in SHR aortic smooth muscle as it is in hypertensive blood cells.

Journal Article↗