Scanning Electron Microscopy And Energy Dispersive X-ray Analysis Research Articles

Potential Usage of Hybrid Polymers Binders Based on Fly Ash with the Addition of PVA with Satisfying Mechanical and Radiological Properties.

Since recycled technologies usage is mandatory for environmental safety, and in this regard, it is important to examine new materials that can be used in construction and are primarily produced from fly ash. In addition to characteristics such as hardness and compressive strength, the given materials must also be radiologically and environmentally safe. The main concept of engineered geopolymer gel composites based on fly ash residues is focused on developing binder materials via gel formation processes that can replace ordinary cement materials. This study is unique in researching the potential use of fly ash from the Nikola Tesla thermal power plant in Serbia, where the hybrid geopolymeric materials synthesized from fly ash are experimentally examined with the addition 1 wt% and 2 wt% of polyvinyl alcohol (PVA). This paper aims to investigate the structural, morphological, mechanical, and radiological properties of hybrid materials with the addition of PVA and without additive in the period of ageing for 28 days at room temperature. The phase composition was investigated using X-ray powder diffraction (XRPD) analysis, while morphological characteristics of these materials were examined using scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDS). Vibrational spectra of obtained samples are investigated using diffuse reflectance infrared Fourier transform (DRIFT) and Fourier transform infrared (FTIR) techniques. The hardness and compressive strength are also examined, indicating that the 1 wt% addition in geopolymeric matrix results in the best mechanical properties. Radiological measurements of investigated all geopolymer samples show decreasing activity concentrations of radionuclides for 50% compared to fly ash.

Magnesium/silicon atomic weight percent ratio standards for the tissue identification of talc by scanning electron microscopy and energy dispersive X-ray analysis

ABSTRACTTalc may lodge in human tissues through various routes, and has been associated with the development of ovarian carcinoma in case control epidemiologic studies. Talc is detected in tissues with scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), with expected magnesium (Mg) and silicon (Si) peaks. The theoretical atomic weight % Mg/Si ratio for talc is 0.649, and for diagnostic purposes, a range of ± 5% (~0.617 to 0.681) is often used as a standard. Our goal was to establish empirically the quantitative range for talc identification by SEM/EDS using two source materials: a Johnson’s Baby PowderTM (cosmetic-grade) consumer sample, and talc from Sigma-Aldrich (particle-grade material intended for scientific use). We examined 401 Mg-Si particles with SEM/EDS across the two samples, using two different SEM microscopes. Overall, we found a mean Mg/Si atomic weight % ratio of 0.645, with minimal differences between study subsets. The standard deviation was 0.025; (± 1σ = 0.620–0.670). The currently used ± 5% diagnostic range (Mg/Si 0.617–0.681) is thus reasonably close to this study’s ± 1σ range, and well within a ± 2 σ confidence interval span (Mg/Si 0.595–0.695). The ± 5% range is thus an appropriately conservative standard whose continued use seems justified.

Microanalysis of Particle-Based Uranium, Thorium, and Plutonium in Nuclear Workers' House Dust

Abstract Scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), a technique not routinely used to detect radiation, was used to identify radioactive particulate matter in hous...

A self-cleaning surface based on heat treatment of g-C3N4-coated wood prepared by a rapid and eco-friendly method

Abstract A self-cleaning surface treatment has been developed, which is prepared by an eco-friendly and effective two-step method. First, graphitic carbon nitride (g-C3N4) was deposited on the wood surface by vacuum impregnation, followed by heat treatment. The morphology, weight change, dimensional stability, crystal and micro structure, and elemental composition of the wood samples were determined by photography, weighting, swelling rate determination, X-ray diffraction (XRD) and scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDXA). Moreover, contact angle measurements and photocatalytic degradation experiments were carried out with Rhodamine B as the target. It was demonstrated that g-C3N4 is successfully deposited on the wood surface, which lowers the heat treatment temperature and renders photocatalytic properties to the coating. The heat treatment at around 210°C strengthened the immobility of g-C3N4 and increased the surface hydrophobicity. Moreover, the better photocatalytic ability of the surface is accompanied with self-cleaning effects.

Development and characterization of a catalytic membrane for volatile organic compound combustion

Platinum-alumina (Pt/γ-Al 2 O 3 )catalytic membranes were obtained using the reservoir technique for the combustion of volatile organic compounds (VOCs). The membranes were characterized by scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDXA) observation, Brunauer-Emmett-Teller (BET) measurement and gas permeation. Propane (C 3 H 8 ) and n-butane (C 4 H 10 ) combustion was obtained. Maximum VOC conversion for p ropane and n-butane of 93 and 48 (%) was achieved on 3.52wt% Pt catalyst at a temperature of 427 and 259 ( 0 C) and flow rates of between 185-222 and 295-379 (ml/min) without any changes in conversion . The combustion results of C 3 H 8 and C 4 H 10 corroborate with literature on Pt/γ-Al 2 O 3 catalysts. The conversion was achieved using flow-through catalytic membrane reactor operating in the Knudsen flow regime. http://dx.doi.org/10.4314/njt.v37i4.18

Solvothermal hot injection synthesis of core-shell AgNi nanoparticles

Silver-nickel core-shell nanoparticles (NP) were prepared by solvothermal hot injection synthesis by simultaneous thermolysis/reduction of AgNO3 and Ni(acac)2 precursors in the hot mixture of octadecene and oleylamine. Oleylamine decreases decomposition temperature of AgNO3 to that of Ni(acac)2 thus ensuring favorable reaction conditions. The prepared AgNi NPs with different Ag/Ni ratios were completely characterized. Dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) were used for particle size characterization of as-prepared AgNi colloids. There is no dependence of the particle size (13–21 nm by SAXS) on the Ag/Ni stoichiometric ratio, but the ultraviolet–visible spectroscopy (UV–vis) reveals that the intensity of the surface plasmon (SPR) decreases with increasing Ni content. Transmission electron microscopy (TEM) verified the results of DLS and SAXS and showed spherical nanoparticle shape. Distribution of individual elements in the nanoparticles was mapped by high resolution scanning transmission electron microscopy and energy dispersive X-ray spectroscopy (STEM-EDS) and revealed their core-shell structure where an Ag nucleus is covered by a thin amorphous Ni layer. Upon heating to 400 °C, Ni crystallization is substantiated by appearance of diffractions in the high-temperature X-ray powder diffractograms (HT-XRD) and of a magnetic moment. Ultimate phase separation was proven by scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDS) in samples heated to 1000 °C. The reaction course and nanoparticle formation studied by DLS, UV–vis, and Ag and Ni elemental analyses reveal an initial Ag seed formation with subsequent Ni overlayer deposition after 180 s.

Effect of Casein Phosphopeptide-amorphous Calcium Phosphate and Calcium Sodium Phosphosilicate on Artificial Carious Lesions: An in vitro Study.

Aim To compare new remineralizing agents calcium sodium phosphosilicate paste and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste with that of fluoridated toothpaste in remineralization of early carious lesions using scanning electron microscopy and energy-dispersive X-ray (SEM-EDX) analysis.Materials and methods Sixty sound extracted premolars were collected and placed in demineralizing solution for 4 days to produce artificial carious lesions. All specimens were evaluated for any loss of mineral content using SEM-EDX analysis. Samples were randomly assigned to three groups: Group I: Fluoridated toothpaste (control), group II: CPP-ACP paste, and group III: Calcium sodium phosphosilicate paste. Specimens were then treated with above-mentioned remineralizing agents and again measured for mineral content using SEM-EDX analysis.Results Group III (calcium sodium phosphosilicate paste) showed highest significant difference followed in descending order by group II (CPP-ACP paste) and group I (fluoridated toothpaste).Conclusion Calcium sodium phosphosilicate paste showed maximum remineralizing potential compared with CPP-ACP and fluoridated toothpastes.How to cite this article Chaudhary I, Tripathi AM, Yadav G, Saha S. Effect of Casein Phosphopeptide-amorphous Calcium Phosphate and Calcium Sodium Phosphosilicate on Artificial Carious Lesions: An in vitro Study. Int J Clin Pediatr Dent 2017;10(3):261-266.

Modification of natural clinoptilolite and ZSM-5 with different oxides and studying of the obtained products in lignin pyrolysis

In this work, different metal oxides (MO) supported on two types of zeolites: 1) natural clinoptilolite (NZ) and 2) synthetic zeolite, ZSM-5 were prepared and tested as catalysts in the fast pyrolysis of hardwood lignin. NZ was modified with the CaO and MgO by a simple two steps procedure consisting of an ion exchange reaction and a subsequent calcination at 773 K. The synthetic ZSM-5 was modified with several MO species (Ni, Cu, Ca, Mg) by a wet impregnation and calcination at 873 K. ?he prepared catalysts were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS) and measurement of specific surface area (BET method). Acid sites were characterized and quantified by pyridine (py) absorption using Fourier transform infrared spectroscopy (FTIR). The catalysts exhibit catalytic activity depanding on modification, reaction temperature and of the MO contents. The highest yield of useful phenol in bio-oil was obtained with NiO/ZSM-5 (34.8 wt.%) which exhibits the highest specific surface area and the highest concetration of Br?nsted and Lewis acid sites. The studied catalysts did not increase significantly the content of polycyclic aromatic hydrocarbons (PAHs) and heavy compounds compared to non-catalytic experiment.

Copper and zinc speciation in a biosolids-amended, semiarid grassland soil.

Predicting trace-metal solid-phase speciation changes associated with long-term biosolids land application is important for understanding and improving environmental quality. Biosolids were surface-applied (no incorporation; 0, 2.5, 5, 10, 21, and 30 Mg ha) to a semiarid grassland in 1991 (single application) and 2002 (repeated application). In July 2003, soils were obtained from the 0- to 8-, 8- to15-, and 15- to 30-cm depths in all plots. Using soil pH, soluble anion and cation concentrations from 0.01 mol L CaCl extractions, dissolved organic C (DOC) content, and an estimate of solid phase humic and fulvic acids present, Cu and Zn associated with minerals, hydrous ferric oxides (HFO), organically complexed, electrostatically bound to organic matter (OM), or DOC phases was modeled using Visual Minteq. Scanning electron microscopy and energy-dispersive X-ray analysis (SEM-EDXRA) was also used to identify solid-phase metal associations present in single and repeated biosolids-amended soils. Based on soil solution chemistry in all depths, as modeled using Visual Minteq, >90% of the Cu and >95% of the Zn from the single or repeated biosolids-applied soils were sorbed electrostatically or as mono- or bidentate solid-phase OM complexes. Up to 10 and 5% of the Cu and Zn, respectively, was associated with HFO, with negligible amounts associated with DOC. The SEM-EDXRA of clay-sized separates from all soil depths led to direct observation of Fe-Cu and Fe-Zn associations. Results implied that after surface-applying biosolids either once or twice with up to 30 Mg ha, some shifts occurred in phases controlling Cu and Zn solubility, but solution concentrations remained below drinking water standards.

Structuring of DLC:Ag nanocomposite thin films employing plasma chemical etching and ion sputtering

We analyze structuring effects of diamond like carbon based silver nanocomposite (DLC:Ag) thin films by CF4/O2 plasma chemical etching and Ar+ sputtering. DLC:Ag films were deposited employing unbalanced reactive magnetron sputtering of silver target with Ar+ in C2H2 gas atmosphere. Films with different silver content (0.6–12.9at.%) were analyzed. The films (as deposited and exposed to plasma chemical etching) were characterized employing scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), optical microscopy, ultraviolet–visible light (UV–VIS) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. After deposition, the films were plasma chemically etched in CF4/O2 mixture plasma for 2–6min. It is shown that optical properties of thin films and silver nano particle size distribution can be tailored during deposition changing the magnetron current and C2H2/Ar ratio or during following plasma chemical etching. The plasma etching enabled to reveal the silver filler particle size distribution and to control silver content on the surface that was found to be dependent on Ostwald ripening process of silver nano-clusters. Employing contact lithography and 4μm period mask in photoresist or aluminum the films were patterned employing CF4/O2 mixture plasma chemical etching, direct Ar+ sputtering or combined etching processes. It is shown that different processing recipes result in different final grating structures. Selective carbon etching in CF4/O2 gas mixture with photoresist mask revealed micrometer range lines of silver nanoparticles, while Ar+ sputtering and combined processing employing aluminum mask resulted in nanocomposite material (DLC:Ag) micropatterns.

Modification of natural clinoptilolite for the nitrate removal from water media

The natural zeolitic tuff from the Zlatokop mine (Vranjska Banja deposit) has been investigated as a starting material for obtaining a low cost adsorbent for the removal of nitrate from water media. The tuff riched with zeolite - clinoptilolite was modified by simple procedures by several oxides: iron(III), manganese(IV) and magnesium in order to make clinoptilolite surface accessible for binding the nitrate ions. The obtained oxide-modified zeolite samples were characterized by scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), powder X-ray diffraction (PXRD), infrared spectroscopy (FTIR) and by measurement of specific surface area. The effects of the adsorbent dosage (0.5, 1.0, 1.5 and 2.0 g), temperature (25, 35 and 45 ?C) and initial nitrate concentration (C0= 100, 200 and 300 mg dm-3) on the binding efficiency were also studied. For all adsorbents the efficiency increases with temperature. The type of oxides effects the adsorption mechanism and Fe(III) oxide modified zeolite exhibits the best binding ability. For this adsorbent the adsorption kinetics was studied and found that it is best represented by the pseudo-second-order model.

Use of scanning electron microscopy to investigate records of soil weathering preserved in lake sediment

Reconstruction of soil weathering is one of the more difficult problems for palaeoecologists interested in landscape-scale environmental changes. Here we use scanning electron microscopy and energy dispersive x-ray analysis (SEM/EDS) to study the pitting of feldspars in soils and lake sediments at two sites in the Great Lakes region, USA. A semi-quantitative feldspar weathering index (FWI) allows description of the weathering status for large numbers of individual grains, and reveals differences among soil horizons and strata of lake sediment as well as between the two sites. Feldspars in upper soil horizons generally have greater FWI than those in lower horizons, but analyses also suggest considerable weathering in the soil C horizon at the site with more rapid water infiltration. At one site, the FWI of upper soil horizons and surface lake sediment are similar, implying that lake sediments have the potential to record changes in soil over time. However, differ ences between upper soil horizons and surface sediment at the other site highlight the need to examine more sites and more profiles within sites to better relate catchment and sediment characteristics. We interpret increases in the FWI over time within lake sediments as evidence of progressive weathering of soils and conclude that the sites had different histories of soil development. However, the complexities of sediment deposition in lakes and the paucity of information relating FWI to soil characteristics prevent straightforward reconstruction of soil development. Variability within each record appears tied to initial grain chemistry, depo sitional environment, changes in lake level and progressive degradation of grains. As more information relating micromorphology to soil characteristics becomes available, this technique should become a more useful complement to chemical studies of lake sediment.

Distribution of Trace Elements in Soils from the Sudbury Smelting Area (Ontario, Canada)

The sequential extraction procedure proposed by the European Commission Measurement and Testing Programme, combined with Scanning Electron Microscopy and Energy Dispersive X-ray Analysis(SEM/EDS), was applied to identify and quantify the chemical andmineralogical forms of Cu, Ni, Fe, Mn, Zn, Pb, Cr and Cd presentin the topsoil from a mining and smelting area near Sudbury (Ontario, Canada). The possible mobility of the chemical forms was also assessed. The metal fractions: (1) soluble and exchangeable, (2) occluded in manganese oxides and in easily reducible iron oxides, (3) organically bound and in form of sulphides, (4) residual mainly present in the mineral lattice structures were separated. Cu and Ni were the major metallic contaminants, occurring in soils in broad ranges of concentrations: Cu 11–1890 and Ni 23–2150 mg kg-1. Cu was uniformly distributed among allthe extracted fractions. Ni was found associated mainly withthe residual forms, accounting for 17–92%, with an averageof 64%, of the total Ni present in the soils. Fe, Mn, Zn,Pb, Cr and Cd, while occurring in most analysed samples innormal soil concentrations, were primarily held in theresidual mineral fraction (on average >50%). The solubleand exchangeable forms made a small contribution (≤8.1%)to the total content of metals extracted. At least 14% ofthe total Cd, Mn and Pb was mobilised from the reducibleforms. The oxidizable fraction assumed mean values higher than10% only for Pb and Zn. Statistical treatment of the experimental data showed significant correlations between totalmetal content of the soils, some soil properties such as pH value, clay and organic matter content, and metal concentrationsin the various fractions. SEM/EDS analysis showed Fe in form ofoxides and sulphides in soils and Cu, Ni, Mn, Zn and Cr in association with iron oxides. Numerous black carbonaceous particles and precipitates of aluminium fluoride salts, observedin the solid residue left after `total’ digestion, were found tocontain Fe, Ni and Cr.

Surveying for Migration Pathways in the Granitic Rock Using Nuclear Track Detectors, Autoradiography and Digital Image Analysis as an Aid To Construct the Basis for Heterogeneous Diffusion Modeling

ABSTRACTRadioelement migration within a rock matrix under natural long-term conditions is a complex process controlled by various parameters. Pure physical parameters such as porosity, hydraulic conductivity and diffusivity are usually sufficient to describe transport in well-defined laboratory systems. In natural rock matrices transport is influenced by physical pore properties such as pore size distribution, connectivity, tortuosity, constrictivity and petrological and chemical nature and charge on the fluid-rock interface. The overall characterization of heterogeneous rock structures is needed for the accurate heterogeneous diffusion modeling.Here we describe a method for the detection of μ-particles from uranium in cm-scale rock samples based on the analysis of the tracks formed in organic polymer, CR-39. On the other hand the uranium tracks were compared with the migration pathways and porosity distribution produced with the 14C-polymethylmethacrylate impregnation method (14C-PMMA). For analyzing mineral specific uranium occurrence and porosities the staining methods were used to produce the mineral map of the rock sample. Digital image analysis techniques were applied to the different cm-scale pictures of rock samples. Scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS) were performed in order both to study the pore apertures of grain boundaries and fissures in greater detail and to detect the uranium phases.The high uranium content was found to be congruent with the porous mineral phases; altered plagioclase and biotite grains, and the intra- and intergranular fissures detected with the 14C-PMMA technique. Plenty of microfractures transsecting potassium feldspar and quartz grains were filled with calcite together with precipitated uranium.

Internal micromorphology of the frons plate in females of the oriental hornet.

Scanning electron microscopy and energy dispersive x-ray analysis (SEM/EDS) have been used to study the internal micromorphology of the frons plate in the Oriental hornet, Vespa orientalis. A conical shaped organ was described which is recessed into the frons plate and projects toward the interior of the acoustic box. The latter is located on the inner side of the frons plate. On the exterior of the conical region are observed aggregates containing Ca and Si, and a thin transparent membrane bearing a hole in its center. The innermost surface of the conical structure terminates bluntly as a convex lentiform tip, bearing a transparent oval-shaped window in its center. The conical organ, excepting the window, is enclosed in several layers of epithelium. The structure of this many-layered conical organ is highly complex; its numerous sub-structures and the possible role as a gravity sense organ are discussed. © 1993 Wiley-Liss, Inc.

The Use of Plasma Ashing on Samples for Detection of Gunshot Residues with Scanning Electron Microscopy and Energy-Dispersive X-Ray Analysis (SEM/EDXA)

Abstract A method is described for the removal of organic material from the adhesive tape employed for collecting particles on the hands. It utilizes the coupled action of contamination by the electron beam of the scanning electron microscope (SEM) and oxygen plasma ashing. The cells of the epidermis are destroyed and only thin filaments are left, while particles that were previously concealed become evident. The treatment does not alter the morphology or composition of gunshot residue (GSR) or of inorganic environmental particles.

Use of Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis (SEM-EDXA) in Identification of Foreign Material on Bullets

The authors report two cases in which examination of foreign material embedded in or adherent to bullets provided critical information in the reconstruction of a crime scene. Analysis of small particles by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) can be accomplished without destruction or injury of the particles. In one case, the detection and identification of mineral fragments embedded near the nose of a bullet provided conclusive evidence that the bullet had ricocheted from a fireplace before striking the victim. In the second case, analysis of particles from two bullets identified them as them as bone fragments, thus proving which shots fired from a police officer's gun had killed a suspected burglar. SEM-EDXA has not been widely used to identify such material on bullets, but should be considered a potentially powerful tool in forensic science.