scholarly journals An electron microscopic histochemical and analytical X-ray microprobe study of calcification in Bruch's membrane from human eyes.

1981 ◽  
Vol 29 (5) ◽  
pp. 601-608 ◽  
Author(s):  
W L Davis ◽  
R G Jones ◽  
H K Hagler
Keyword(s):  
Electron Microscopy ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Phosphotungstic Acid ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Dense Deposits ◽  
Calcium And Phosphorus ◽  
Human Eyes

Transmission electron microscopy, electron microprobe analysis, high temperature microincineration, and electron microscopic histochemical procedures were used to study the electron-dense deposits characteristic of the macular aspect of aged human eyes. These inorganic deposits were rich in calcium and phosphorus and selectively removed by flotation on formic acid. The amorphous decalcified masses showed a significant sulfur peak and were readily stained with acidic phosphotungstic acid. The latter observations are indicative of the presence of organic matrical proteoglycan. Such data may be a further indication that proteoglycans are retained at sites of calcification.

Investigation of Natural and Artificial Zr-silicate Gels

2006 ◽  
Vol 932 ◽  
Author(s):  
Boris E. Burakov ◽  
Andrey Ph. Smetannikov ◽  
Evgeniy B. Anderson ◽  
Alexander Yu. Alexeev
Keyword(s):  
Electron Microscopy ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Chemical Durability ◽  
High Chemical ◽  
X Ray ◽  
Transmission Electron ◽  
Oxide Phases ◽  
Intermediate Storage

ABSTRACTSample of natural Zr-silicate gel containing up to 13 wt.% U was characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and electron microprobe analysis (EPMA) method. It was found that gel matrix is amorphous in general; however, it contains non-identified nanocrystallites. No separated oxide phases of U, Zr or Si were observed in a gel matrix. After sintering in air at 1400°C for 1 hour gel transformed largely into crystalline zircon, (Zr,U)SiO4. Uranium was not found in any other phases besides zircon. It was assumed that high chemical durability of natural Zr-P-U-Ti-silicate gel is caused by two competing processes which exist under self-irradiation conditions: 1) crystallization of the gel and 2) metamictization of the crystallized zircon and other phases.Synthetic samples of Zr-silicate gel doped with Ce, U, Pu and Am were obtained and studied in comparison with natural samples. It was suggested to use artificial solid Zr-silicate gels for durable fixation of actinides for the goal of long-term or intermediate storage.

scholarly journals Efflorescent Sulfate Crystallization on Fractured and Polished Colloform Pyrite Surfaces: A Migration Pathway of Trace Elements

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 12
Author(s):  
Dimitrina Dimitrova ◽  
Vassilka Mladenova ◽  
Lutz Hecht
Keyword(s):  
Electron Microscopy ◽  
Trace Elements ◽  
Inductively Coupled Plasma ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
X Ray ◽  
Inductively Coupled ◽  
Migration Pathway ◽  
Plasma Mass Spectrometry ◽  
Scanning Electron

The colloform pyrite variety incorporates many trace elements that are released in the environment during rapid oxidation. Colloform pyrite from the Chiprovtsi silver–lead deposit in Bulgaria and its oxidation efflorescent products were studied using X-ray diffractometry, scanning electron microscopy, electron microprobe analysis, and laser ablation inductively coupled plasma mass spectrometry. Pyrite is enriched with (in ppm): Co (0.1–964), Ni (1.8–3858), Cu (2.9–3188), Zn (3.1–77), Ag (1.2–1771), As (8179–52,787), Se (2.7–21.7), Sb (48–17792), Hg (4–2854), Tl (1.7–2336), Pb (13–7072), and Au (0.07–2.77). Gypsum, anhydrite, szomolnokite, halotrichite, römerite, copiapite, aluminocopiapite, magnesiocopiapite, coquimbite, aluminocoquimbite, voltaite, and ammoniomagnesiovoltaite were identified in the efflorescent sulfate assemblage. Sulfate minerals contain not only inherited elements from pyrite (Cr, Fe, Co, Ni, Cu, Zn, Ag, In, As, Sb, Hg, Tl, and Pb), but also newly introduced elements (Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Mn, Ga, Rb, Sr, Y, Zr, Sn, Cs, Ba, REE, U, and Th). Voltaite group minerals, copiapite, magnesiocopiapite, and römerite incorporate most of the trace elements, especially the most hazardous As, Sb, Hg, and Tl. Colloform pyrite occurrence in the Chiprovtsi deposit is limited. Its association with marbles would further restrict the oxidation and release of hazardous elements into the environment.

scholarly journals Synthesis, Characterization, and Photocatalytic Performance of Mesoporous α-Mn2O3 Microspheres Prepared via a Precipitation Route

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Manoj Pudukudy ◽  
Zahira Yaakob
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Thermal Transformation ◽  
Xrd Analysis ◽  
Structural Deformation ◽  
Blue Dye ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron

α-Mn2O3 microspheres with high phase purity, crystallinity, and surface area were synthesized by the thermal decomposition of precipitated MnCO3 microspheres without the use of any structure directing agents and tedious reaction conditions. The prepared Mn2O3 microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) and photoluminescence (PL) studies. The complete thermal transformation of MnCO3 to Mn2O3 was clearly shown by the FTIR and XRD analysis. The electron microscopic images clearly confirmed the microsphere-like morphology of the products with some structural deformation for the calcined Mn2O3 sample. The mesoporous texture generated from the interaggregation of subnanoparticles in the microstructures is visibly evident from the TEM and BET studies. Moreover, the Mn2O3 microstructures showed a moderate photocatalytic activity for the degradation of methylene blue dye pollutant under UV light irradiation, using air as the potential oxidizing agent.

Mercury and selenium localization in macrophages of the striped dolphin, Stenella coeruleoalba

1994 ◽  
Vol 74 (4) ◽  
pp. 975-978
Author(s):  
Marco Nigro
Keyword(s):  
Electron Microscopy ◽  
Microprobe Analysis ◽  
Spherical Particles ◽  
Stenella Coeruleoalba ◽  
X Ray ◽  
Striped Dolphin ◽  
Selenium Accumulation ◽  
Transmission Electron ◽  
And Storage

The cellular features of mercury and selenium accumulation has been studied by transmission electron microscopy and x-ray microprobe analysis in the liver of striped dolphins. Mercury and selenium occurred as dense intracellular granules, located mainly within the liver macrophages (Kupffer cells). Granules were composed of 150 A spherical particles showing the same electron diffraction pattern and x-ray spectrum as mercuric selenide. The role of macrophages in mercuric selenide granule production and storage is discussed.

Characterization of metallurgical grade silicon

1990 ◽  
Vol 5 (9) ◽  
pp. 1894-1899 ◽  
Author(s):  
J. C. Anglézio ◽  
C. Servant ◽  
F. Dubrous
Keyword(s):  
Electron Microscopy ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Optical Metallography ◽  
Metallurgical Grade Silicon ◽  
Transmission Electron ◽  
Grade Silicon ◽  
Precipitated Phases ◽  
Scanning Electron

Optical metallography, scanning electron microscopy, electron microprobe analysis, and transmission electron microscopy were used to characterize metallurgical grade silicon, produced in an electric are furnace. Coincidence fraction determinations were assumed to be Σ7 and Σ9 when grain boundaries are underlined by precipitated phases and Σ3 when they are not. The study of intergranular compounds was emphasized; ten compounds were found, the main ones being Si2Ca, Si8Al6Fe4Ca, Si2Al2Ca, Si2FeTi, and Si2.4Fe (α leboitc). The precipitation of these compounds was discussed according to the principal impurity concentrations in silicon. The crystalline structure of Si8Al6Fe4Ca was determined to be triclinic with a = 1.3923 nm, b = 1.3896 nm, c = 1.3900 nm and α = 92.4°, β = 110.3°, γ = 119.9°.

Electron microprobe analysis of the distribution of silicon in the leaves of Selaginella emmeliana

1980 ◽  
Vol 58 (23) ◽  
pp. 2459-2466 ◽  
Author(s):  
Nancy G. Dengler ◽  
Eric Y-C. Lin
Keyword(s):  
Electron Microscopy ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Cell Types ◽  
Preliminary Survey ◽  
Leaf Epidermis ◽  
Abaxial Side ◽  
X Ray ◽  
Tangential Wall ◽  
Scanning Electron

Scanning electron microscopy and X-ray microanalysis of the ventral leaves of Selaginella emmeliana demonstrated high levels of silicon in the marginal sclereids and about one-half the abaxial epidermal cells. Although both of these cell types bear rows of knobs or warts on the outer tangential wall, the X-ray spectra indicate that silicon is distributed throughout the wall and that it is not concentrated in these projections. In S. emmeliana, stomata are confined to a band of low silicon cells overlying the midrib on the abaxial side of the leaf. A small proportion of these stomata also contain high levels of silicon and are characterized by a constricted stomatal aperture. A preliminary survey of three other species of Selaginella indicates that accumulation of silicon in the leaf epidermis is characteristic for each.

Magnetite exsolution in almandine garnet

1986 ◽  
Vol 50 (358) ◽  
pp. 621-633 ◽  
Author(s):  
A. J. Brearley ◽  
P. E. Champness
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Microprobe ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Spinel Phase ◽  
Analytical Electron Microscopy ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Rare Situation

AbstractThree almandine-rich metamorphic garnets have been studied by analytical electron microscopy and electron microprobe analysis. Electron microprobe analyses with total Fe calculated as Fe2+ show that there are no significant departures from stoichiometry due to the presence of Fe3+ in any of the garnets studied. However, in the transmission electron microscope (TEM) all the garnets were found to contain myriad spherical, iron-rich particles up to 400 Å in diameter. Microdiffraction techniques have revealed that the particles are a cubic spinel phase, consistent with magnetite. There is no crystallographic relationship between the host garnet and the particles, a rare situation for exsolution processes. The presence of such particles is interpreted in terms of the exsolution of magnetite from almandine garnet during cooling. This can apparently occur at temperatures below 55°C. The size of the particles is a qualitative indicator of the cooling rate of the rock, but is also dependent on the original Fe3+ content of the host garnet.

scholarly journals How Microanalysis Can Be Discriminant on Black Pompeian Wares

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 879
Author(s):  
Laura Medeghini ◽  
Silvano Mignardi ◽  
Giorgia Di Fusco ◽  
Michela Botticelli ◽  
Fulvio Coletti ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Analytical Approach ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Specific Production ◽  
X Ray ◽  
Black Layer ◽  
Scanning Electron

In the present work the advantages of punctual approaches are discussed in the discrimination of black wares from the Sanctuary of Venus Fisica (Pompeii, Italy), dated between the 2nd and 1st century BC. Black-gloss ware and "bucchero" samples are analyzed by a multi-analytical approach including optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy with Energy Dispersive Spectroscopy (SEM-EDS) and electron microprobe analysis (EMPA) to investigate the mineralogical and petrographic features of these artefacts. Grain size, firing conditions and potter’s expertise influenced the final appearance of the superficial decorative black layer. In addition, punctual chemical analysis was fundamental to verify the archaeological indication of specific production sites.

A Study of Natural Metamict Yttrium Niobate as Analogue of Actinide Ceramic Waste Form

2014 ◽  
Vol 1665 ◽  
pp. 313-318 ◽  
Author(s):  
Cao Qiuxiang ◽  
Anton I. Isakov ◽  
Liu Xiaodong ◽  
Sergey V. Krivovichev ◽  
Boris E. Burakov
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Single Phase ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Original Sample ◽  
X Ray Diffraction ◽  
Average Chemical Composition ◽  
X Ray ◽  
Scanning Electron

ABSTRACTNatural metamict mineral found as large (1-3 cm in size) homogeneous grains (as assumed, former single crystals), was investigated by X-ray powder diffraction (pXRD), high-temperature pXRD, scanning electron microscopy (SEM) and electron microprobe analysis (EMPA). The average chemical composition obtained by EMPA is (wt. %): Nb2O5 – 42.6; Ta2O5 – 4.4; TiO2 – 9.2; UO3 – 4.4; ThO2 – 1.0; MnO – 1.3; FeO – 19.4; Y2O3 – 16.6.The untreated (original) sample is X-ray amorphous. The sample remained amorphous after annealing at 400 °C for 1 hour. The sample became almost fully crystalline after annealing at 700 °C for 1 hour with an X-ray diffraction pattern similar to that of Fe-columbite (ICCD: 01-074-7356). Further annealing at 1000 °C and higher temperatures caused changes in the phase composition of the sample. It was proposed that under self-irradiation a single-phase U-Th-bearing solid solution, based on monocrystalline Y-niobate, became metamict but remained homogeneous without evidence of solid solution destruction. However, this metamict solid solution is unstable under thermal treatment and recrystallization.

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