Direct Determination of Apatite in Lake Sediments

1980 ◽  
Vol 37 (4) ◽  
pp. 640-646 ◽  
Author(s):  
R. P. Reid ◽  
C. H. Pharo ◽  
W. C. Barnes
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lake Sediments ◽  
Trophic State ◽  
Inorganic Phosphorus ◽  
Source Rocks ◽  
Emission Spectrometry ◽  
Phosphorus Load ◽  
Lake Trophic State ◽  
Scanning Electron

Apatite is a common accessory mineral in the source rocks for the glacial debris supplying sediments to many Canadian lakes. A method has been developed which uses scanning electron microscopy and energy dispersive X-ray emission spectrometry for direct identification of apatite. This method has been used to examine the apatite content of various size fractions in Kamloops Lake sediments. Apatite concentrations obtained by this direct examination correlate well (r > 0.999) with apatite concentrations determined by chemical analyses and indicate that, in addition to comprising as much as 70% of the total phosphorus load, apatite may comprise as much as one-third of the "dissolved" (< 0.45 μm) inorganic phosphorus load. Consequently the use of classical (e.g. Vollenweider 1968; Vollenweider and Dillon 1974) methods of estimating lake trophic state from inorganic phosphorus concentrations in lake water must be done with care, recognizing that the bulk of inorganic phosphorus in lakes deriving sediment from glaciated igneous or metamorphic terrains may be in the form of apatite.Key words: apatite, lake, trophic state, phosphorus load, scanning electron microscopy

scholarly journals CHEMICAL AND PHISICAL CHARACTERIZATION OF MEMORY BOARDS FROM OBSOLETE COMPUTERS THROUGH OPTICAL EMISSION SPECTROMETRY AND SCANNING ELECTRON MICROSCOPY

2019 ◽  
Vol 16 (2) ◽  
pp. 212-221
Author(s):  
Marcos Paulo Kohler Caldas ◽  
Mariana Alves de Carvalho ◽  
Viviane Tavares de Moraes ◽  
Jorge Alberto Soares Tenório ◽  
Denise Crocce Romano Espinosa
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Optical Emission ◽  
Optical Emission Spectrometry ◽  
Emission Spectrometry ◽  
Scanning Electron

Staurosirella andino-patagonica sp. nov. (Bacillariophyta) from lake sediments in Patagonia, Argentina

Phytotaxa ◽  
2019 ◽  
Vol 402 (3) ◽  
pp. 131 ◽  
Author(s):  
JOSÉ MARÍA GUERRERO ◽  
MARÍA LUJÁN GARCÍA ◽  
EDUARDO A. MORALES
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lake Sediments ◽  
Surface Sediments ◽  
Geographic Area ◽  
New Taxon ◽  
Diatom Flora ◽  
The Andes ◽  
Distinct Morphology ◽  
Scanning Electron

Staurosirella andino-patagonica, a new araphid diatom found in Holocene and recent surface sediments from lakes located in the Andes and adjacent steppe of Patagonia (Argentina), is described on the basis of light and scanning electron microscopy observations and comparison with related taxa. Although the elliptic valve outline of the new taxon resembles the smaller specimens of several Staurosirella species, ultrastructural features such as the presence of two spines on each virga and their distinct morphology -serrated with thickenings at the base- make Staurosirella andino-patagonica unique within the genus. Our study contributes to the knowledge of the Patagonian araphid diatom flora, a rather unexplored geographic area, and so we assume that, as additional areas are studied in detail, they will likely continue to yield new taxa.

The Corrosion of HDG Zinc Coatings on the Road and Urban Infrastructures

2015 ◽  
Vol 227 ◽  
pp. 217-220
Author(s):  
Agnieszka Królikowska ◽  
Leszek Komorowski
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Gravimetric Method ◽  
Optical Emission ◽  
Emission Spectrometry ◽  
The Road ◽  
On The Road ◽  
Zinc Coatings ◽  
Scanning Electron

The standard ISO 14713-1 shows that HDG coatings should protect steel in the corrosive atmosphere C5 for 10–21 years. It was observed that pitting corrosion appears already after 2–3 years on roads and urban infrastructures and both Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) have shown that lead inclusions were present in all such corroded zinc coatings. The laboratory prepared HDG coatings with different amount of lead inclusions were investigated by gravimetric method (after exposure in salt chamber), SEM with EDS, and Glow Discharge Optical Emission Spectrometry (GDOES). The corrosion resistance was analyzed in the polarization tests and local probe techniques. The inclusions could accelerate coating corrosion because lead is cathodic to zinc.

Understanding variations in reservoir porosity in the Eagle Ford Shale using scanning electron microscopy: implications for basin modelling

2020 ◽  
Vol 484 (1) ◽  
pp. 229-239 ◽  
Author(s):  
Mark Osborne ◽  
Herbert Volk
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Organic Matter ◽  
Pore Size ◽  
Source Rocks ◽  
Thermal Maturity ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Basin Modelling ◽  
Scanning Electron

AbstractReliable evaluation of shale-play potential requires robust geological models that can simulate the generation and retention of petroleum, porosity and permeability in source rocks from first principles, and that can be implemented in basin modelling software. To be predictive, such basin models need to be calibrated against observations from real shale plays. A key control on the amount of retained petroleum is the porosity in the shale and the abundance of organic matter. Scanning electron microscopy of argon-ion milled shale samples can potentially reveal systematic variations in the amount of porosity, pore types and distributions across a range of thermal maturities. These observed variations in porosity can be used to calibrate basin modelling outputs and refine predictive models. For these reasons BP has conducted scanning electron microscopy studies of shale plays including the Eagle Ford Shale, a carbonate-rich mudstone sequence of Cenomanian to Turonian age. The results clearly show that the mean pore size decreases as thermal maturity increases and that organic matter-hosted pores are absent in low thermal maturity samples (where vitrinite random reflectance Ro <0.7) and become increasingly more abundant as thermal maturity increases). In moderately mature samples there are organic matter hosted pores that range in pore size from 5 to 500 nm. In highly mature samples, small (<50 nm) organic matter-hosted pores predominate. Our studies reveal that porosity evolution in this organic-rich, fine-grained, carbonate mudrock shows a strong correlation with increasing thermal maturity.

scholarly journals Assessment of the Impact of the Addition of Nanoparticles on the Properties of Glass–Ionomer Cements

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 276 ◽  
Author(s):  
Elizabeta Gjorgievska ◽  
John W. Nicholson ◽  
Dragana Gabrić ◽  
Zeynep Asli Guclu ◽  
Ivana Miletić ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Compressive Strength ◽  
Tio2 Nanoparticles ◽  
Emission Spectrometry ◽  
Al2o3 Nanoparticles ◽  
Glass Ionomer Cements ◽  
Glass Ionomer ◽  
The Impact ◽  
Scanning Electron

The aim of the study was to evaluate the effects of incorporation of Al2O3, ZrO2 and TiO2 nanoparticles into glass–ionomer cements (GICs). Two different GICs were used in the study. Four groups were prepared for each material: the control group (without nanoparticles) and three groups modified by the incorporation of nanoparticles at 2, 5 or 10 wt %, respectively. Cements were mixed and placed in moulds (4 mm × 6 mm); after setting, the samples were stored in saline (one day and one week). Compressive strengths were measured and the morphology of the fractured surfaces was analyzed by scanning electron microscopy. The elements released into the storage solutions were determined by Inductively coupled plasma-optical emission spectrometry (ICP-OES). Addition of nanoparticles was found to alter the appearance of cements as examined by scanning electron microscopy. Compressive strength increased with the addition of ZrO2 and especially TiO2 nanoparticles, whereas the addition of Al2O3 nanoparticles generally weakened the cements. The ion release profile of the modified cements was the same in all cases. The addition of Al2O3, ZrO2 and TiO2 nanoparticles into GICs is beneficial, since it leads to reduction of the microscopic voids in the set cement. Of these, the use of ZrO2 and TiO2 nanoparticles also led to increased compressive strength. Nanoparticles did not release detectable levels of ions (Al, Zr or Ti), which makes them suitable for clinical use.

scholarly journals Ion release from hydroxyapatite and substituted hydroxyapatites in different immersion liquids: in vitro experiments and theoretical modelling study

2021 ◽  
Vol 8 (1) ◽  
pp. 201785
Author(s):  
Aurora Mocanu ◽  
Oana Cadar ◽  
Petre T. Frangopol ◽  
Ioan Petean ◽  
Gheorghe Tomoaia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bone Tissue Regeneration ◽  
Theoretical Modelling ◽  
Emission Spectrometry ◽  
Release Mechanism ◽  
Ion Release ◽  
Biological Potential ◽  
Scanning Electron

Multi-substituted hydroxyapatites (ms-HAPs) are currently gaining more consideration owing to their multifunctional properties and biomimetic structure, owning thus an enhanced biological potential in orthopaedic and dental applications. In this study, nano-hydroxyapatite (HAP) substituted with multiple cations (Sr 2+ , Mg 2+ and Zn 2+ ) for Ca 2+ and anion ( Si O 4 4 − ) for P O 4 3 − and OH − , specifically HAPc-5%Sr and HAPc-10%Sr (where HAPc is HAP-1.5%Mg–0.2%Zn–0.2%Si), both lyophilized non-calcined and lyophilized calcined, were evaluated for their in vitro ions release. These nanomaterials were characterized by scanning electron microscopy, field emission-scanning electron microscopy and energy-dispersive X-ray, as well as by atomic force microscope images and by surface specific areas and porosity. Further, the release of cations and of phosphate anions were assessed from nano-HAP and ms-HAPs, both in water and in simulated body fluid, in static and simulated dynamic conditions, using inductively coupled plasma optical emission spectrometry. The release profiles were analysed and the influence of experimental conditions was determined for each of the six nanomaterials and for various periods of time. The pH of the samples soaked in the immersion liquids was also measured. The ion release mechanism was theoretically investigated using the Korsmeyer–Peppas model. The results indicated a mechanism principally based on diffusion and dissolution, with possible contribution of ion exchange. The surface of ms-HAP nanoparticles is more susceptible to dissolution into immersion liquids owing to the lattice strain provoked by simultaneous multi-substitution in HAP structure. According to the findings, it is rational to suggest that both materials HAPc-5%Sr and HAPc-10%Sr are bioactive and can be potential candidates in bone tissue regeneration.

Pathogenesis of Human Hair Defects

1974 ◽  
Vol 32 ◽  
pp. 12-13
Author(s):  
P.S. Porter ◽  
T. Aoyagi ◽  
R. Matta
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Human Hair ◽  
Standard Techniques ◽  
Scanning Electron

Using standard techniques of scanning electron microscopy (SEM), over 1000 human hair defects have been studied. In several of the defects, the pathogenesis of the abnormality has been clarified using these techniques. It is the purpose of this paper to present several distinct morphologic abnormalities of hair and to discuss their pathogenesis as elucidated through techniques of scanning electron microscopy.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

Spontaneous Cataract in Nude Athymic Mice

1977 ◽  
Vol 35 ◽  
pp. 512-513
Author(s):  
Ronald H. Bradley ◽  
R. S. Berk ◽  
L. D. Hazlett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Nude Mouse ◽  
Cellular Immunity ◽  
Phosphate Buffer ◽  
Osmium Tetroxide ◽  
Athymic Mice ◽  
Transmission Microscopy ◽  
Mouse Lens ◽  
Scanning Electron

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.

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