Morphological and chemical analysis of bone substitutes by scanning electron microscopy and microanalysis by spectroscopy of dispersion energy.

PubMed

da Cruz, Gabriela Alessandra; de Toledo, Sérgio; Sallum, Enilson Antonio; de Lima, Antonio Fernando Martorelli

2007-01-01

This study evaluated the morphological and chemical composition of the following bone substitutes: cancellous and cortical organic bovine bone with macro and microparticle size ranging from 1.0 to 2.0 mm and 0.25 to 1.0 mm, respectively; inorganic bovine bone with particle size ranging from 0.25 to 1.0 mm; hydroxyapatite with particle size ranging from 0.75 to 1.0 mm; and demineralized freeze-dried bone allograft with particle size ranging from 0.25 to 0.5 mm. The samples were sputter-coated with gold in an ion coater, the morphology was observed and particle size was measured under vacuum by scanning electron microscopy (SEM). The chemical composition was evaluated by spectroscopy of dispersion energy (EDS) microanalysis using samples without coating. SEM analysis provided visual evidence that all examined materials have irregular shape and particle sizes larger than those informed by the manufacturer. EDS microanalysis detected the presence of sodium, calcium and phosphorus that are usual elements of the bone tissue. However, mineral elements were detected in all analyzed particles of organic bovine bone except for macro cancellous organic bovine bone. These results suggest that the examined organic bovine bone cannot be considered as a pure organic material.

Measurement of Trace Constituents by Electron-Excited X-Ray Microanalysis with Energy-Dispersive Spectrometry.

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2016-06-01

Electron-excited X-ray microanalysis performed with scanning electron microscopy and energy-dispersive spectrometry (EDS) has been used to measure trace elemental constituents of complex multielement materials, where "trace" refers to constituents present at concentrations below 0.01 (mass fraction). High count spectra measured with silicon drift detector EDS were quantified using the standards/matrix correction protocol embedded in the NIST DTSA-II software engine. Robust quantitative analytical results for trace constituents were obtained from concentrations as low as 0.000500 (mass fraction), even in the presence of significant peak interferences from minor (concentration 0.01≤C≤0.1) and major (C>0.1) constituents. Limits of detection as low as 0.000200 were achieved in the absence of peak interference.

Rigorous quantitative elemental microanalysis by scanning electron microscopy/energy dispersive x-ray spectrometry (SEM/EDS) with spectrum processing by NIST DTSA-II

NASA Astrophysics Data System (ADS)

Newbury, Dale E.; Ritchie, Nicholas W. M.

2014-09-01

Quantitative electron-excited x-ray microanalysis by scanning electron microscopy/silicon drift detector energy dispersive x-ray spectrometry (SEM/SDD-EDS) is capable of achieving high accuracy and high precision equivalent to that of the high spectral resolution wavelength dispersive x-ray spectrometer even when severe peak interference occurs. The throughput of the SDD-EDS enables high count spectra to be measured that are stable in calibration and resolution (peak shape) across the full deadtime range. With this high spectral stability, multiple linear least squares peak fitting is successful for separating overlapping peaks and spectral background. Careful specimen preparation is necessary to remove topography on unknowns and standards. The standards-based matrix correction procedure embedded in the NIST DTSA-II software engine returns quantitative results supported by a complete error budget, including estimates of the uncertainties from measurement statistics and from the physical basis of the matrix corrections. NIST DTSA-II is available free for Java-platforms at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).

A combination of a SEM technique and X-ray microanalysis for studying the spore germination process of Clostridium tyrobutyricum.

PubMed

Bassi, Daniela; Cappa, Fabrizio; Cocconcelli, Pier Sandro

2009-06-01

Clostridium tyrobutyricum is an anaerobic bacterium responsible for late blowing defects during cheese ripening and it is of scientific interest for biological hydrogen production. A scanning electron microscopy (SEM) coating technique and X-ray microanalysis were developed to analyze the architecture and chemical composition of spores upon germination in response to environmental changes. In addition, we investigated the effects of different compounds on this process. Agents and environmental conditions inducing germination were characterized monitoring changes in optical density (OD). Among all tested conditions, the greatest drop in OD(625) (57.4%) was obtained when spores were incubated in l-alanine/l-lactate buffer, pH 4.6. In addition, a carbon-coating SEM technique and X-ray microanalysis were used to observe the architecture of spores and to examine calcium dipicolinate release. Conditions inducing C. tyrobutyricum spore germination were identified and SEM X-ray microanalysis clearly distinguished germinating from dormant spores. We confirmed that calcium dipicolinate release is one of the first events occurring. These microscopy methods could be considered sensitive tools for evaluating morphological and chemical changes in spores of C. tyrobutyricum during the initial phase of germination. Information gathered from this work may provide new data for further research on germination.

Resistance in mango against infection by Ceratocystis fimbriata.

PubMed

Araujo, Leonardo; Bispo, Wilka Messner Silva; Cacique, Isaías Severino; Moreira, Wiler Ribas; Rodrigues, Fabrício Ávila

2014-08-01

This study was designed to characterize and describe host cell responses of stem tissue to mango wilt disease caused by the fungus Ceratocystis fimbriata in Brazil. Disease progress was followed, through time, in inoculated stems for two cultivars, 'Ubá' (field resistant) and 'Haden' (field susceptible). Stem sections from inoculated areas were examined using fluorescence light microscopy and transmission and scanning electron microscopy, coupled with energy-dispersive X-ray microanalysis. Tissues from Ubá colonized by C. fimbriata had stronger autofluorescence than those from Haden. The X-ray microanalysis revealed that the tissues of Ubá had higher levels of insoluble sulfur and calcium than those of Haden. Scanning electron microscopy revealed that fungal hyphae, chlamydospores (aleurioconidia), and perithecia-like structures of C. fimbriata were more abundant in Haden relative to Ubá. At the ultrastructural level, pathogen hyphae had grown into the degraded walls of parenchyma, fiber cells, and xylem vessels in the tissue of Haden. However, in Ubá, plant cell walls were rarely degraded and hyphae were often surrounded by dense, amorphous granular materials and hyphae appeared to have died. Taken together, the results of this study characterize the susceptible and resistant basal cell responses of mango stem tissue to infection by C. fimbriata.

Energy Dispersive X-ray (EDX) microanalysis: A powerful tool in biomedical research and diagnosis

PubMed Central

Scimeca, Manuel; Bischetti, Simone; Lamsira, Harpreet Kaur; Bonfiglio, Rita; Bonanno, Elena

2018-01-01

The Energy Dispersive X-ray (EDX) microanalysis is a technique of elemental analysis associated to electron microscopy based on the generation of characteristic Xrays that reveals the presence of elements present in the specimens. The EDX microanalysis is used in different biomedical fields by many researchers and clinicians. Nevertheless, most of the scientific community is not fully aware of its possible applications. The spectrum of EDX microanalysis contains both semi-qualitative and semi-quantitative information. EDX technique is made useful in the study of drugs, such as in the study of drugs delivery in which the EDX is an important tool to detect nanoparticles (generally, used to improve the therapeutic performance of some chemotherapeutic agents). EDX is also used in the study of environmental pollution and in the characterization of mineral bioaccumulated in the tissues. In conclusion, the EDX can be considered as a useful tool in all works that require element determination, endogenous or exogenous, in the tissue, cell or any other sample. PMID:29569878

Formation of multicomponent matrix metal oxide films in anodic alumina matrixes by chemical deposition

NASA Astrophysics Data System (ADS)

Gorokh, G. G.; Zakhlebayeva, A. I.; Metla, A. I.; Zhilinskiy, V. V.; Murashkevich, A. N.; Bogomazova, N. V.

2017-11-01

The metal oxide films of SnxZnyOz and SnxMoyOz systems deposited onto anodic alumina matrixes by chemical and ion layering from an aqueous solutions were characterized by scanning electron microscopy, Raman spectroscopy, electron probe X-ray microanalysis and IR spectroscopy. The obtained matrix films had reproducible composition and structure and possessed certain morphological characteristics and properties.

Use of scanning electron microscopy and microanalysis to determine chloride content of concrete and raw materials : [summary].

DOT National Transportation Integrated Search

2013-01-01

The Florida Department of Transportation (FDOT) is responsible for the maintenance of thousands of concrete structures that are exposed to or situated in salt water. Considering the significant cost of each of these structures, FDOT would like a 75-y...

Scattered electrons in microscopy and microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottensmeyer, F.P.

The use of scattered electrons alone for direct imaging of biological specimens makes it possible to obtain structural information at atomic and near-atomic spatial resolutions of 0.3 to 0.5 nanometer. While this is not as good as the resolution possible with x-ray crystallography, such an approach provides structural information rapidly on individual macromolecules that have not been, and possibly cannot be, crystallized. Analysis of the spectrum of energies of scattered electrons and imaging of the latter with characteristic energy bands within the spectrum produces a powerful new technique of atomic microanalysis. This technique, which has a spatial resolution of aboutmore » 0.5 nanometer and a minimum detection sensitivity of about 50 atoms of phosphorus, is especially useful for light atom analysis and appears to have applications in molecular biology, cell biology, histology, pathology, botany, and many other fields.« less

Scattered electrons in microscopy and microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ottensmeyer, F.P.

The use of scattered electrons alone for direct imaging of biological specimens makes it possible to obtain structural information at atomic and near-atomic spatial resolutions of 0.3 to 0.5 nanometer. While this is not as good as the resolution possible with x-ray crystallography, such an approach provides structural information rapidly on individual macromolecules that have not been, and possibly cannot be, crystallized. Analysis of the spectrum of energies of scattered electrons and imaging of the latter with characteristic energy bands within the spectrum produce a powerful new technique of atomic microanalysis. This technique, which has a spatial resolution of aboutmore » 0.5 nanometer and a minimum detection sensitivity of about 50 atoms of phosphorus, is especially useful for light atom analysis and appears to have applications in molecular biology, cell biology, histology, pathology, botany, and many other fields.« less

Composition, speciation and distribution of iron minerals in Imperata cylindrica.

PubMed

Amils, Ricardo; de la Fuente, Vicenta; Rodríguez, Nuria; Zuluaga, Javier; Menéndez, Nieves; Tornero, Jesús

2007-05-01

A comparative study of the roots, rhizomes and leaves of an iron hyperaccumulator plant, Imperata cylindrica, isolated from the banks of an extreme acidic environment, using complementary techniques: Mösbauer spectroscopy (MS), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled to energy-dispersive X-ray microanalysis (EDAX) and transmission electron microscopy (TEM), has shown that two main biominerals, jarosite and ferrihydrate-ferritin, accumulate in the different tissues. Jarosite accumulates mainly in roots and rhizomes, while ferritin has been detected in all the structures. A model of iron management in I. cylindrica is presented.

FIB preparation of a NiO Wedge-Lamella and STEM X-ray microanalysis for the determination of the experimental k(O-Ni) Cliff-Lorimer coefficient.

PubMed

Armigliato, Aldo; Frabboni, Stefano; Gazzadi, Gian Carlo; Rosa, Rodolfo

2013-02-01

A method for the fabrication of a wedge-shaped thin NiO lamella by focused ion beam is reported. The starting sample is an oxidized bulk single crystalline, <100> oriented, Ni commercial standard. The lamella is employed for the determination, by analytical electron microscopy at 200 kV of the experimental k(O-Ni) Cliff-Lorimer (G. Cliff & G.W. Lorimer, J Microsc 103, 203-207, 1975) coefficient, according to the extrapolation method by Van Cappellen (E. Van Cappellen, Microsc Microstruct Microanal 1, 1-22, 1990). The result thus obtained is compared to the theoretical k(O-Ni) values either implemented into the commercial software for X-ray microanalysis quantification of the scanning transmission electron microscopy/energy dispersive spectrometry equipment or calculated by the Monte Carlo method. Significant differences among the three values are found. This confirms that for a reliable quantification of binary alloys containing light elements, the choice of the Cliff-Lorimer coefficients is crucial and experimental values are recommended.

Effect of shape and thickness of asbestos bundles and fibres on EDS microanalysis: A Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Moro, D.; Valdre, G.

2016-02-01

Quantitative microanalysis of tiny asbestos mineral fibres by scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDS) still represents a complex analytical issue. This complexity arises from the variable fibre shape and small thickness (< 5 μm) compared with the penetration of the incident electron beam. Here, we present the results of Monte Carlo simulations of chrysotile, crocidolite and amosite fibres (and bundles of fibres) of circular and square section and thicknesses from 0.1 μm to 10 μm, to investigate the effect of shape and thickness on SEM-EDS microanalysis. The influence of shape and thickness on the simulated spectrum was investigated for electron beam energies of 5, 15 and 25 keV, respectively. A strong influence of the asbestos bundles and fibres shape and thickness on the detected EDS X-ray intensity was observed. The X-ray intensity trends as a function of fibre thickness showed a non-linear dependence for all the elements and minerals. In general, the X-ray intensities showed a considerable reduction for thicknesses below about 5 μm at 5 keV, 2 μm at 15 keV, and 5 μm at 25 keV. Correction parameters, k-ratios, for the asbestos fibre thickness effect, are reported.

Characterization of Discontinuous Coarsening Reaction Products in INCONEL® Alloy 740H® Fusion Welds

NASA Astrophysics Data System (ADS)

Bechetti, Daniel H.; Dupont, John N.; Watanabe, Masashi; de Barbadillo, John J.

2017-04-01

Characterization of γ' coarsened zones (CZs) in alloy 740H fusion welds via a variety of electron microscopy techniques was conducted. The effects of solute partitioning during nonequilibrium solidification on the amount of strengthening precipitates along the grain boundaries were evaluated via electron-probe microanalysis and scanning electron microscopy. Electron backscatter diffraction was used to present evidence for the preferential growth of CZs toward regions of lower γ' content, even if growth in that direction increases grain boundary area. Scanning electron microscopy and image analysis were used to quantify the propensity for CZs to develop along certain segments of the grain boundaries, as governed by the local variations in γ' content. Scanning transmission electron microscopy with X-ray energy-dispersive spectrometry (XEDS) was used to assess the compositions of the matrix and precipitate phases within the CZs and to quantify the segregation of alloying components to the reaction front. Thermodynamic and kinetic modeling were used to compare calculated and experimental compositions. The work presented here provides new insight into the progression of the discontinuous coarsening (DC) reaction in a complex engineering alloy.

Cysticercosis of the fallopian tube: histology and microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham, J.L.; Spore, W.W.; Benirschke, K.

1982-07-01

The authors identified a degenerated, focally calcified cestode larva (cysticercus) in the fallopian tube of a 50-year-old woman with endometriosis. The physiologic reaction to the larva was minimal, with some focal granulomatous salpingitis. No other focus of infection was detected. The differential diagnosis included trophoblastic tissue, foreign material, and parasites. Scanning electron microscopy and x-ray microanalysis of the organism revealed concentration of iodine in the subcuticular connective tissue of the larva and confirmed the calcium phosphate composition of the calcareous corpuscles. The presumed source of the iodine was the continued exposure of the larva to an environment rich in iodidemore » secreted by the epithelium of the fallopian tube.« less

PREFACE: European Microbeam Analysis Society's 14th European Workshop on Modern Developments and Applications in Microbeam Analysis (EMAS 2015), Portorož, Slovenia, 3-7 May 2015

NASA Astrophysics Data System (ADS)

Llovet, Xavier; Matthews, Michael B.; Čeh, Miran; Langer, Enrico; Žagar, Kristina

2016-02-01

This volume of the IOP Conference Series: Materials Science and Engineering contains papers from the 14th Workshop of the European Microbeam Analysis Society (EMAS) on Modern Developments and Applications in Microbeam Analysis which took place from the 3rd to the 7th of May 2015 in the Grand Hotel Bernardin, Portorož, Slovenia. The primary aim of this series of workshops is to assess the state-of-the-art and reliability of microbeam analysis techniques. The workshops also provide a forum where students and young scientists starting out on a career in microbeam analysis can meet and discuss with the established experts. The workshops have a unique format comprising invited plenary lectures by internationally recognized experts, poster presentations by the participants and round table discussions on the key topics led by specialists in the field.This workshop was organized in collaboration with the Jožef Stefan Institute and SDM - Slovene Society for Microscopy. The technical programme included the following topics: electron probe microanalysis, STEM and EELS, materials applications, cathodoluminescence and electron backscatter diffraction (EBSD), and their applications. As at previous workshops there was also a special oral session for young scientists. The best presentation by a young scientist was awarded with an invitation to attend the 2016 Microscopy and Microanalysis meeting at Columbus, Ohio. The prize went to Shirin Kaboli, of the Department of Metals and Materials Engineering of McGill University (Montréal, Canada), for her talk entitled "Electron channelling contrast reconstruction with electron backscattered diffraction". The continuing relevance of the EMAS workshops and the high regard in which they are held internationally can be seen from the fact that 71 posters from 16 countries were on display at the meeting and that the participants came from as far away as Japan, Canada, USA, and Australia. A selection of participants with posters was invited to give a short oral presentation of their work in three dedicated sessions. The prize for the best poster was an invitation to participate in the 24th Australian Conference on Microscopy and Microanalysis (ACMM 24) in Melbourne, Australia. The prize was awarded to Aurélien Moy of the University of Montpellier (France) for his poster entitled: "Standardless quantification of heavy metals by electron probe microanalysis". This proceedings volume contains the full texts of 9 of the invited plenary lectures and of 12 papers on related topics originating from the posters presented at the workshop. All the papers have been subjected to peer review by a least two referees.

Subcellular distribution of an inhalational anesthetic in situ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckenhoff, R.G.; Shuman, H.

1990-01-01

To better understand the mechanisms and sites of anesthetic action, we determined the subcellular partitioning of halothane in a tissue model. A method was found to fix the in vivo distribution of halothane in rat atrial tissue for subsequent electron microscopy and x-ray microanalysis. Atrial strips were exposed to various concentrations of halothane, rapidly frozen, cryo-sectioned, and cryo-transferred into an electron microscope. Irradiation of the hydrated cryosections with the electron beam caused halothane radiolysis, which allowed retention of the halogen-containing fragments after dehydration of the sections. The bromine from halothane was detected and quantified with x-ray microanalysis in various microregionsmore » of atrial myocytes. Halothane (bromine) partitioned largely to mitochondria, with progressively lower concentrations in sarcolemma, nuclear membrane, cytoplasm, sarcomere, and nucleus. Partitioning could not be explained solely by distribution of cellular lipid, suggesting significant and differential physicochemical solubility in protein. However, we found no saturable compartment in atrial myocytes within the clinical concentration range, which implies little specific protein binding.« less

Electron microscopy and microanalysis of the fiber-matrix interface in monolithic silicone carbide-based ceramic composite material for use in a fusion reactor application.

PubMed

Toplisek, Tea; Drazic, Goran; Novak, Sasa; Kobe, Spomenka

2008-01-01

A composite material made from continuous monolithic silicone carbide (SiC) fibers and a SiC-based matrix (SiC(f)/SiC), was prepared using a novel technique, i.e. adapted dip coating and infiltration of SiC fibers with a water suspension containing SiC particles and a sintering additive. This kind of material could be used in the first-wall blanket of a future fusion reactor. Using magnetron sputtering, the SiC fibers were coated with various thin layers (TiC, CrN, CrC, WC, DLC-diamond-like carbon) of the interface material by physical vapor deposition (PVD). Using scanning and transmission electron microscopy and microanalysis, detailed microstructural studies of the fiber-matrix interface were performed. Both samples, with coated and uncoated fibers, were examined under a load. The microcracks introduced by the Vickers indenter continued their path through the fibers, and thus caused the failure of the composite material, in the case of the uncoated fibers or deviated from their primary direction at the fiber-matrix interface in the case of the coated fibers.

Correlative Instrumental Neutron Activation Analysis, Light Microscopy, Transmission Electron Microscopy, and X-ray Microanalysis for Qualitative and Quantitative Detection of Colloidal Gold Spheres in Biological Specimens

NASA Astrophysics Data System (ADS)

Hillyer, Julián F.; Albrecht, Ralph M.

1998-10-01

: Colloidal gold, conjugated to ligands or antibodies, is routinely used as a label for the detection of cell structures by light (LM) and electron microscopy (EM). To date, several methods to count the number of colloidal gold labels have been employed with limited success. Instrumental neutron activation analysis (INAA), a physical method for the analysis of the elemental composition of materials, can be used to provide a quantitative index of gold accumulation in bulk specimens. Given that gold is not naturally found in biological specimens in any substantial amount and that colloidal gold and ligand conjugates can be prepared to yield uniform bead sizes, the amount of label can be calculated in bulk biological samples by INAA. Here we describe the use of INAA, LM, transmission EM, and X-ray microanalysis (EDX) in a model to determine both distribution (localization) and amount of colloidal gold at the organ, tissue, cellular, and ultrastructural levels in whole animal systems following administration. In addition, the sensitivity for gold in biological specimens by INAA is compared with that of inductively coupled plasma mass spectrometry (ICP-MS). The correlative use of INAA, LM, TEM, and EDX can be useful, for example, in the quantitative and qualitative tracking of various labeled molecular species following administration in vivo.

Electrolytic Reduction of Titania Slag in Molten Calcium Chloride Bath

NASA Astrophysics Data System (ADS)

Mohanty, Jayashree

2012-05-01

Ferro-titanium is prepared by direct electrolytic reduction of titania-rich slag obtained from plasma smelting of ilmenite in molten CaCl2. The product after electro-reduction is characterized by x-ray diffraction, scanning electron microscopy, and electron probe microanalysis. The electrolysis is carried out at a cell voltage of 3.0 V, taking graphite as the electrolysis cell as well as the anode, and a titania-rich slag piece wrapped by a nichrome wire is used as the cathode.

[Bone defect replacement under conditions of transosseous osteosynthesis and titanium nickelide implant application].

PubMed

Ir'ianov, Iu M; Ir'ianova, T Iu

2012-01-01

In the experiment conducted on 30 Wistar rats, the peculiarities of tibial bone defect replacement under conditions of transosseous osteosynthesis and implantation of titanium nickelide mesh structures were studied using the methods of scanning electron microscopy and x-ray electron probe microanalysis. It was demonstrated that implant osseointegration occured 7 days after surgery, and after 30 days the defect was replaced with bone tissue by the type of primary bone wound healing, thus the organotypical remodeling of regenerated bone took place.

Inter-layered clay stacks in Jurassic shales

NASA Technical Reports Server (NTRS)

Pye, K.; Krinsley, D. H.

1983-01-01

Scanning electron microscopy in the backscattered electron mode is used together with energy-dispersive X-ray microanalysis to show that Lower Jurassic shales from the North Sea Basin contain large numbers of clay mineral stacks up to 150 microns in size. Polished shale sections are examined to determine the size, shape orientation, textural relationships, and internal compositional variations of the clays. Preliminary evidence that the clay stacks are authigenic, and may have formed at shallow burial depths during early diagenesis, is presented.

Correlated Microanalysis of Cometary Organic Grains Returned by Stardust

NASA Technical Reports Server (NTRS)

DeGregorio, B. T.; Stroud, R. M.; Nittler, L. R.; Cody, G. D,; Kilcoyne, A. L. D.

2011-01-01

Preliminary examination (PE) of samples returned from Comet 81P/Wild 2 by the NASA Stardust mission revealed a wide variety of carbonaceous samples [e.g. 1]. Carbonaceous matter is present as inclusions, rinds, and films in polyminerallic terminal particles [2-4], as carbon-rich particles along track walls [2, 5, 6], and as organic matter in aerogel around tracks [7, 8]. The organic chemistry of these samples ranges from purely aliphatic hydrocarbons to highly-aromatic material, often modified by various organic functional groups [2, 4, 5, 9-11]. Difficulty arises when interpreting the genesis of these carbonaceous samples, since contaminants could be introduced from the spacecraft [12], aerogel [1, 8], or during sample preparation. In addition, hypervelocity capture into aerogel may have heated cometary material in excess of 1000 C, which could have significantly altered the structure and chemistry of carbonaceous matter. Fortunately, much of this contamination or alteration can be identified through correlated microanalysis with transmission electron microscopy (TEM), scanning-transmission X-ray microscopy (STXM), and nanoscale secondary ion mass spectroscopy (SIMS).

Characterisation of phases in nanostructured, multilayered titanium alloys by analytical and high-resolution electron microscopy.

PubMed

Czyrska-Filemonowicz, A; Buffat, P A

2009-01-01

Surface processing of a Ti-6Al-4V alloy led to a complex multilayered microstructure containing several phases of the Ni-Ti-P-Al-O system, which improves the mechanical and tribological surface properties. The microstructure, chemical and phase compositions of the hard layer formed on the surface were investigated by LM, XRD, SEM as well as analytical/high-resolution TEM, STEM, EDS, electron diffraction and FIB. Phase identification based on electron diffraction, HRTEM and EDS microanalysis revealed the presence of several binary and ternary phases in the system Ti-Ni-P, sometimes with partial substitution of Ti by Al. However some phases, mainly nanoparticles, still remain not identified satisfactorily. Electron microscopy techniques used for identification of phases present in surface multilayers and some practical limits to their routine application are reminded here.

Electrodeposition of thin yttria-stabilized zirconia layers using glow-discharge plasma

NASA Astrophysics Data System (ADS)

Ogumi, Zempachi; Uchimoto, Yoshiharu; Tsuji, Yoichiro; Takehara, Zen-ichiro

1992-08-01

A novel process for preparation of thin yttria-stabilized zirconia (YSZ) layers was developed. This process differs from other vapor-phase deposition methods in that a dc bias circuit, separate from the plasma-generation circuit, is used for the electrodeposition process. The YSZ layer was electrodeposited from ZrCl4 and YCl3 on a nonporous calcia-stabilized zirconia substrate. Scanning electron microscopy, electron probe microanalysis, electron spectroscopy for chemical analysis, and x-ray-diffraction measurements confirmed the electrodeposition of a smooth, pinhole-free yttria-stabilized zirconia film of about 3 μm thickness.

Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods

NASA Astrophysics Data System (ADS)

Goudarzi, Mojgan; Mir, Noshin; Mousavi-Kamazani, Mehdi; Bagheri, Samira; Salavati-Niasari, Masoud

2016-09-01

In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM).

Cryo-Scanning Electron Microscopy (SEM) and Scanning Transmission Electron Microscopy (STEM)-in-SEM for Bio- and Organo-Mineral Interface Characterization in the Environment.

PubMed

Wille, Guillaume; Hellal, Jennifer; Ollivier, Patrick; Richard, Annie; Burel, Agnes; Jolly, Louis; Crampon, Marc; Michel, Caroline

2017-12-01

Understanding biofilm interactions with surrounding substratum and pollutants/particles can benefit from the application of existing microscopy tools. Using the example of biofilm interactions with zero-valent iron nanoparticles (nZVI), this study aims to apply various approaches in biofilm preparation and labeling for fluorescent or electron microscopy and energy dispersive X-ray spectrometry (EDS) microanalysis for accurate observations. According to the targeted microscopy method, biofilms were sampled as flocs or attached biofilm, submitted to labeling using 4',6-diamidino-2-phenylindol, lectins PNA and ConA coupled to fluorescent dye or gold nanoparticles, and prepared for observation (fixation, cross-section, freezing, ultramicrotomy). Fluorescent microscopy revealed that nZVI were embedded in the biofilm structure as aggregates but the resolution was insufficient to observe individual nZVI. Cryo-scanning electron microscopy (SEM) observations showed nZVI aggregates close to bacteria, but it was not possible to confirm direct interactions between nZVI and cell membranes. Scanning transmission electron microscopy in the SEM (STEM-in-SEM) showed that nZVI aggregates could enter the biofilm to a depth of 7-11 µm. Bacteria were surrounded by a ring of extracellular polymeric substances (EPS) preventing direct nZVI/membrane interactions. STEM/EDS mapping revealed a co-localization of nZVI aggregates with lectins suggesting a potential role of EPS in nZVI embedding. Thus, the combination of divergent microscopy approaches is a good approach to better understand and characterize biofilm/metal interactions.

Viscosity of the liquid Al-6Mg-1Mn-0.2Sc-0.1Zr alloy

NASA Astrophysics Data System (ADS)

Reznik, P. L.; Chikova, O. A.; Tsepelev, V. S.

2017-07-01

The microstructure and the phase composition of as-cast Al-Mg-Mn-Sc-Zr alloy samples are studied by electron microscopy and electron-probe microanalysis. The processes of solidification and melting of this alloy are described. The temperature dependence of the kinematic viscosity of the Al-Mg-Mn-Sc-Zr melts is studied during heating and subsequent cooling of the samples. The measurement results are used to determine the temperature at which inherited microheterogeneities in the melts are destroyed irreversibly.

Segregation Phenomena on the Crystal Surface of Chemical Compounds

NASA Astrophysics Data System (ADS)

Tomashpol'skii, Yu. Ya.

2018-06-01

The current state of the theoretical and experimental studies of changes in the chemical structure and composition caused by segregation phenomena on the surface of chemical compounds was reviewed. The review considers the experimental data obtained exclusively on single crystals, which were studied by modern instrumental methods, including in situ Auger electron spectrometry, X-ray spectral microanalysis, high-resolution scanning and transmission electron microscopy, secondary electron emission, and atomic force microscopy. The models that suggest the crystal-chemical diffusion and liquid-phase mechanisms of segregation were described. The parameters of the theory include the type of chemical bond, elastic constants, and crystal-chemical characteristics of substances. The models make it possible to predict the nature of changes in the surface composition: segregation tendency, segregant type, and degree of nonstoichiometry. A new direction in surface segregation was considered, which is promising for nanoelectronics and emission electronics.

Secondary sulfate minerals from Alum Cave Bluff: Microscopy and microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lauf, R.J.

1997-07-01

Microcrystals of secondary sulfate minerals from Alum Cave Bluff, Great Smoky Mountains National Park, were examined by scanning electron microscopy and identified by X-ray fluorescence (XRF) in the SEM. Among the samples the author discovered three new rare-earth sulfates: coskrenite-(Ce), levinsonite-(Y), and zugshunstite-(Ce). Other minerals illustrated in this report include sulfur, tschermigite, gypsum, epsomite, melanterite, halotrichite, apjohnite, jarosite, slavikite, magnesiocopiapite, and diadochite. Additional specimens whose identification is more tentative include pickeringite, aluminite, basaluminite, and botryogen. Alum Cave is a ``Dana locality`` for apjohnite and potash alum, and is the first documented North American occurrence of slavikite.

Application of micro-Fourier transform infrared spectroscopy to the examination of paint samples

NASA Astrophysics Data System (ADS)

Zięba-Palus, J.

1999-11-01

The examination and identification of automobile paints is an important problem in road accidents investigations. Since the real sample available is very small, only sensitive microtechniques can be applied. The methods of optical microscopy and micro-Fourier transform infrared spectroscopy (MK-FTIR) supported by scanning electron microscopy together with X-ray microanalysis (SEM-EDX) allow one to carry out the examination of each paint layer without any separation procedure. In this paper an attempt is made to discriminate between different automobile paints of the same colour by the use of these methods for criminalistic investigations.

Non-fibrous inorganic particles in bronchoalveolar lavage fluid of pottery workers.

PubMed Central

Falchi, M; Paoletti, L; Mariotta, S; Giosue, S; Guidi, L; Biondo, L; Scavalli, P; Bisetti, A

1996-01-01

AIM: To study the actual exposure of pottery workers to silica particles, as their risk of silicosis is potentially high because of the presence of inhalable crystalline silica particles in the workplace. METHODS: Nine pottery workers underwent bronchoalveolar lavage. The recovered fluid was analysed for cytological and mineralogical content by analytical transmission electron microscopy. The data were compared with those obtained from a control group composed of seven patients with sarcoidosis and six patients with haemoptysis. RESULTS: Cytological results showed a similar profile in exposed workers and controls, whereas in patients with sarcoidosis a lymphocytic alveolitis was found. Microanalysis of the particulate identified the presence of silicates, CRSs, and metals. Pottery workers had higher numbers of total particles and CRSs, and had a higher silicate/metal ratio. In five workers, the presence of zirconium silicate was also detected. Patients with sarcoidosis had the lowest number of particles, and an inverted silicate/metal ratio. CONCLUSION: Microanalysis by transmission electron microscope can provide useful information to assess occupational exposure to dusts. PMID:9038801

Microstructural stability of wrought, laser and electron beam glazed NARloy-Z alloy at elevated temperatures

NASA Technical Reports Server (NTRS)

Singh, J.; Jerman, G.; Bhat, B.; Poorman, R.

1993-01-01

Microstructure of wrought, laser, and electron-beam glazed NARloy-Z(Cu-3 wt.% Ag-0.5 wt.% Zr) was investigated for thermal stability at elevated temperatures (539 to 760 C (1,100 to 1,400 F)) up to 94 h. Optical and scanning electron microscopy and electron probe microanalysis were employed for studying microstructural evolution and kinetics of precipitation. Grain boundary precipitation and precipitate free zones (PFZ's) were observed in the wrought alloy after exposing to temperatures above 605 C (1,120 F). The fine-grained microstructure observed in the laser and electron-beam glazed NARloy-Z was much more stable at elevated temperatures. Microstructural changes correlated well with hardness measurements.

The role of an organic matrix during the formation of siliceous scales in the heliozoon Actinophrys sol (actinophryida, protista).

PubMed

Newman, P J; Patterson, D J

1993-07-25

Actinophrys sol is a freshwater heliozoon which has trophic and encysted body forms. During encystment, siliceous scales are laid down in silica deposition vesicles. The scales form one layer of a multi-layered cyst wall. Scale production is described using light microscopy, transmission electron microscopy, scanning electron microscopy, and X-ray microanalysis. Silica is laid down on an organic matrix which is visible prior to silicification and after removal of silica with hydrofluoric acid. Actinophrys sol can be cultured under silica impoverished conditions, with the result that the siliceous plates are absent. The cysts continue to form but are fragile. Silica is not a prerequisite for the processes of encystment and cyst formation. Copyright © 1993 Gustav Fischer Verlag · Stuttgart · Jena · New York. Published by Elsevier GmbH.. All rights reserved.

Performance of a Commercial Silicon Drift Detector for X-ray Microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenik, Edward A

2008-01-01

Silicon drift detectors (SDDs) are rapidly becoming the energy dispersive spectrometer of choice especially for scanning electron microscopy applications. The complementary features of large active areas (i.e., collection angle) and high count rate capability of these detector contribute to their popularity, as well as the absence of liquid nitrogen cooling of the detector. The performance of an EDAX Apollo 40 SDD on a JEOL 6500F SEM will be discussed.

X-ray microanalysis of black piedra.

PubMed

Figueras, M J; Guarro, J

1997-11-01

The elements present in the fungal structures produced by Piedraia hortae in vivo and in vitro have been investigated using electron microscopy X-ray microanalysis. Phosphorus, sulphur and calcium were detected in the nodules which developed on hair and on colonies on culture. These elements belong to the extracellular material that compacts the pseudoparenchymatous organization of the fungus. They may be present due to the capacity of melanin-like pigments to sequester ions and/or they may form part of the sulphates and phosphates of the polyanionic mucopolysaccharides that constitute the extracellular material. Environmental contaminants such as aluminium, silicon and iron were detected exclusively on the surface of the nodule. They were deposited or linked to the residual molecules produced during the breakdown of the cuticular keratin. The advantages of these techniques for elucidating the chemical nature of fungal structures are discussed.

Multi-walled carbon nanotubes decorated by platinum catalyst nanoparticles--examination and microanalysis using scanning and transmission electron microscopies.

PubMed

Guinel, M J-F; Brodusch, N; Verde-Gómez, Y; Escobar-Morales, B; Gauvin, R

2013-10-01

Carbon nanotubes (CNTs) decorated with platinum (Pt) nanoparticles (NPs) have been characterized using a cold field-emission scanning electron microscope (SEM) and a high resolution field-emission transmission electron microscope (TEM). With this particular composite material, the complementary nature of the two instruments was demonstrated. Although the long CNTs were found to be mostly bent and defective in some parts, the nucleation of Pt occurred randomly and uniformly covered the CNTs. The NPs displayed a large variation in size, were sometimes defective with twins and stacking faults, and were found to be faceted with the presence of surface steps. The shape and size of the NPs and the presence of defects may have significant consequences on the activity of the Pt catalyst material. Also, thin layers of platinum oxide were identified on the surface of some NPs. © 2013 The Authors Journal of Microscopy © 2013 Royal Microscopical Society.

Structure of a radiate pseudocolony associated with an intrauterine contraceptive device

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, P.K.; Lea, P.J.; Roth-Moyo, L.A.

Transmission electron microscopy of a radiate pseudocolony associated with an intrauterine contraceptive device (IUCD) showed central bundles of extracellular fibers averaging 35 nm in diameter, surrounded by layered mantles of electron-dense, amorphous granular material. No bacterial, viral, or fungal structures were present. X-ray microanalysis revealed copper, sulfur, chloride, iron, and phosphorus; no calcium was found. It is postulated that these structures and histologically identical non-IUCD-associated granules from the female genital tract, as well as similar structures from other body locations, including those reported in colloid cysts of the third ventricle, are of lipofuscin origin.

Crystallization of the glassy phase of grain boundaries in silicon nitride

NASA Technical Reports Server (NTRS)

Jefferson, D. A.; Thomas, J. M.; Wen, S.

1984-01-01

Three types of hot-pressed silicon nitride specimens (containing 5wt% Y2O3 and 2wt% Al2O3 additives) which were subjected to different temperature heat treatments were studied by X-ray diffraction, X-ray microanalysis and high resolution electron microscopy. The results indicated that there were phase changes in the grain boundaries after heat treatment and the glassy phase at the grain boundaries was crystallized by heat treatment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vilches, J.; Lopez, A.; Martinez, M.C.

This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.

Imaging interactions of metal oxide nanoparticles with macrophage cells by ultra-high resolution scanning electron microscopy techniques.

PubMed

Plascencia-Villa, Germán; Starr, Clarise R; Armstrong, Linda S; Ponce, Arturo; José-Yacamán, Miguel

2012-11-01

Use of engineered metal oxide nanoparticles in a plethora of biological applications and custom products has warned about some possible dose-dependent cytotoxic effects. Macrophages are key components of the innate immune system used to study possible toxic effects and internalization of different nanoparticulate materials. In this work, ultra-high resolution field emission scanning electron microscopy (FE-SEM) was used to offer new insights into the dynamical processes of interaction of nanomaterials with macrophage cells dosed with different concentrations of metal oxide nanoparticles (CeO(2), TiO(2) and ZnO). The versatility of FE-SEM has allowed obtaining a detailed characterization of processes of adsorption and endocytosis of nanoparticles, by using advanced analytical and imaging techniques on complete unstained uncoated cells, including secondary electron imaging, high-sensitive backscattered electron imaging, X-ray microanalysis and stereoimaging. Low voltage BF/DF-STEM confirmed nanoparticle adsorption and internalization into endosomes of CeO(2) and TiO(2), whereas ZnO develop apoptosis after 24 h of interaction caused by dissolution and invasion of cell nucleus. Ultra-high resolution scanning electron microscopy techniques provided new insights into interactions of inorganic nanoparticles with macrophage cells with high spatial resolution.

Monte Carlo simulation of the effect of shape and thickness on SEM-EDS microanalysis of asbestos fibres and bundles: the case of anthophyllite, tremolite and actinolite

NASA Astrophysics Data System (ADS)

Valdrè, G.; Moro, D.; Ulian, G.

2018-01-01

Asbestos is a generic term used for six types of silicate minerals that are found in fibres or bundles of fibres, which can be easily cleaved into thinner ones. Scanning electron microscopy energy-dispersive X-ray spectrometry (SEM-EDS) quantitative microanalysis of asbestos mineral fibres still represents a complex analytical issue because of the variable fibre shape and small thickness (< 5 μm) compared with the penetration depth of the incident electron beam. Following previous work on chrysotile, crocidolite and amosite, here we present a study by means of Monte Carlo simulations of the thickness and shape effect on SEM-EDS microanalysis of anthophyllite, tremolite and actinolite asbestos. Realistic experimental conditions, such as sample geometry, SEM set-up and detector physics were taken into account. We report the results obtained on 100 μm long fibres and bundles of circular and square section and thicknesses from to 0.1 μm to 10 μm, for electron beam energies of 5, 15 and 25 keV. A strong influence of the asbestos mineral fibres and bundles shape and thickness on the detected EDS X-ray intensity was observed. In general, the X-ray intensities as a function of fibre thickness showed a considerable reduction below about 0.5 μm at 5 keV, 2 μm at 15 keV, and 5 μm at 25 keV for all the elements and minerals, with a non-linear dependence. Correction parameters, k-ratio, for the thickness effect were calculated and proposed.

Complementary microanalysis of Zn, Mn and Fe in the chelicera of spiders and scorpions using scanning MeV-ion and electron microprobes

NASA Astrophysics Data System (ADS)

Schofield, Robert; Lefevre, Harlan; Shaffer, Michael

1989-04-01

Energy-loss scanning transmission ion microscopy (ELSTIM or just STIM), PIXE and electron microprobe techniques are used to investigate certain minor element accumulations in a few spiders and scorpions. STIM and PIXE are used to survey the unsectioned specimens, while electron microprobe techniques are used for higher resolution investigations of several sections of the specimens. Concentration values measured using STIM and PIXE are found to be in satisfactory agreement with those measured using electron probe microanalysis. A garden spider Araneus diadematus is found to contain high concentrations of zinc in a thin layer near the surface of its fangs (reaching 23% of dry weight), and manganese in its marginal teeth (about 5% of dry weight). A wolf spider Alopecosa kochi is found to have similar concentrations of zinc in a layer near the surface of it's fang, and concentrations of manganese reaching 1.5% in a layer beneath the zinc containing layer. A scorpion Centruroides sp. is found to contain high concentrations of iron (reaching 8%) and zinc (reaching 24%) in the tips of teeth on the cheliceral fingers, and manganese (about 5%) in the stinger. The hypothesis that these elements simply harden the cuticle does not appear to explain their segregation patterns.

Application of Quantitative Analytical Electron Microscopy to the Mineral Content of Insect Cuticle

NASA Astrophysics Data System (ADS)

Rasch, Ron; Cribb, Bronwen W.; Barry, John; Palmer, Christopher M.

2003-04-01

Quantification of calcium in the cuticle of the fly larva Exeretonevra angustifrons was undertaken at the micron scale using wavelength dispersive X-ray microanalysis, analytical standards, and a full matrix correction. Calcium and phosphorus were found to be present in the exoskeleton in a ratio that indicates amorphous calcium phosphate. This was confirmed through electron diffraction of the calcium-containing tissue. Due to the pragmatic difficulties of measuring light elements, it is not uncommon in the field of entomology to neglect the use of matrix corrections when performing microanalysis of bulk insect specimens. To determine, firstly, whether such a strategy affects the outcome and secondly, which matrix correction is preferable, phi-rho (z) and ZAF matrix corrections were contrasted with each other and without matrix correction. The best estimate of the mineral phase was found to be given by using the phi-rho (z) correction. When no correction was made, the ratio of Ca to P fell outside the range for amorphous calcium phosphate, possibly leading to flawed interpretation of the mineral form when used on its own.

Efforts to identify Te-rich nano-islands in ZnSe

NASA Astrophysics Data System (ADS)

Lau, June W.; Volkov, Vyacheslav V.; Zhu, Yimei; Kuskovsky, Igor L.; Neumark, Gertrude F.; Lin, W.; Maksimov, Oleg; Tamargo, Maria C.

2002-03-01

Much work has been done on the study of nano-island formation (“dopants”) in various systems by use of electron microscopy, often complemented by x-ray microanalysis [1]. This works well for systems involving one or more monolayers of dopants. Our system consists of Te and N dopants incorporated into ZnSe in sub-monolayer quantities [2]. This presents a challenge; our calculations show that this case is probably below the detection limit of x-ray microanalysis. Our samples do show strain contrasts but we were unable to obtain direct confirmation of nano-islands’ existence. As an alternative, dark field images from chemically sensitively reflections were used in volumetric defect density studies. The defect density in the doped samples was higher than that of the undoped samples. 1. Dorin C., U of Mich. Poster presentation at Fall MRS meeting 2001 2. Lin et al., Apple. Phys. Let., 76, 2205 (2000).

Properties of calcium-containing microparticles formed in the process of biomineralization of the human aortic wall

NASA Astrophysics Data System (ADS)

Zlatoustova, O. Yu; Vasilev, S. V.; Rudy, A. S.

2016-08-01

The results of the study of human aortic walls, subjected to different stages of mineralization are presented. By means of scanning electron microscopy and X-ray microanalysis the morphology, elemental composition and characteristics of the mineral component localization were investigated. The key differences in the initial, intermediate and final stages of pathological mineralization of the aorta wall were identified. The data obtained may be useful in describing the mechanism of biomineral deposits formation in human body.

Studies of the Ossicles from the Ciliate Protozoan Spirostomum ambiguum

NASA Astrophysics Data System (ADS)

Takagui, Regina; Silveira, Marina

1999-09-01

Spirostomum ambiguum is able to concentrate intracellular deposits of calcium phosphate. This mineralization process is dependent on the age of the culture and can be stimulated by an applied piezoelectric potential. Crystalline deposits induced to form in laboratory cultures were analysed both in situ and after isolation from the cells, using transmission and scanning electron microscopies, energy dispersive microanalysis, and optical spectrophotometry. The ratio of Ca:P (1.57±0.01) fits with the expected value for hydroxyapatite.

High Rate Deposition of Thick CrN and Cr2N Coatings Using Modulated Pulse Power (MPP) Magnetron Sputtering

DTIC Science & Technology

2010-12-01

in the conventional Bragg-Bentano mode. The residual stress of the coatings was measured by glancing incident angle XRD (GIXRD) in the same X - ray ...micro-analysis (EPMA), x - ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), nanoindentation, scratch test, and ball-on...the coatings was determined by XRD using a SIEMENS X - ray diffractometer (Model KRISTALLOFLEX-810) operated with K-alpha Cu radiation (30 kV and 20 mA

Studies on the cellular and subcellular reactions in epidermis at irritant and allergic dermatitis.

PubMed

Lindberg, M

1982-01-01

To determine the cellular and subcellular reactions of keratinocytes at contact dermatitis, transmission electron microscopy was used in combination with energy dispersive X-ray microanalysis. Stereology and optical diffraction were used as complements to electron microscopy for studies of the effects of variations in the preparation technique on the ultrastructure of epidermis. The morphological effects of an increased hydration of epidermis were assessed by the use of occlusive patch tests. It was found that the relative volume of the epidermal intercellular space and the ultrastructure of the epidermal cells (keratinocytes and Langerhans' cells) were directly dependent on the osmolality of the fixative vehicle if glutaraldehyde was used as fixative. Cellular volume and morphology did also depend on the fixative used. Variations in the volume of the intercellular space were also detected when the water transport through epidermis was impaired by occlusive treatment. In normal epidermis prolonged fixation times (4 weeks) did not affect the morphology of the keratinocytes. However, if the structure and function of the keratinocytes were affected by the application of a irritant substance (DNCB), a loss of electron dense material from the cells was detected within 3 weeks. The ultrastructural changes in the keratinocytes at the irritant chromate and DNCB reactions were of a non-specific nature and are in accordance with the changes described for other irritant agents in the literature. A few cells with the features of apoptosis were recorded. The allergic chromate reaction was found to be a combination of the irritant reaction and a marked inflammatory response. To correlate the ultrastructural alterations in the keratinocytes with the functional state of the cells, X-ray microanalysis was used to determine the elemental redistribution occurring at the irritant DNCB reaction. The results of the X-ray microanalysis showed a good correlation between dose and time dependent effects and with the ultrastructural changes. Cell injury in the keratinocytes lead to decreases in the cellular content of phosphorous, potassium and magnesium and an increase of cellular calcium. Sodium, chloride, and sulphur were only moderately changed. A stimulation of the basal keratinocytes was detectable when a weak DNCB dose was applied to the skin.

Electron Probe MicroAnalysis (EPMA) Standards. Issues Related to Measurement and Accuracy Evaluation in EPMA

NASA Technical Reports Server (NTRS)

Carpenter, Paul

2003-01-01

Electron-probe microanalysis standards and issues related to measurement and accuracy of microanalysis will be discussed. Critical evaluation of standards based on homogeneity and comparison with wet-chemical analysis will be made. Measurement problems such as spectrometer dead-time will be discussed. Analytical accuracy issues will be evaluated for systems by alpha-factor analysis and comparison with experimental k-ratio databases.

Mineralogy of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, Vermont

USGS Publications Warehouse

Levitan, D.M.; Hammarstrom, J.M.; Gunter, M.E.; Seal, R.R.; Chou, I.-Ming; Piatak, N.M.

2009-01-01

Samples from the surfaces of waste piles at the Vermont Asbestos Group mine in northern Vermont were studied to determine their mineralogy, particularly the presence and morphology of amphiboles. Analyses included powder X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and Raman spectroscopy. Minerals identified by XRD were serpentine-group minerals, magnetite, chlorite, quartz, olivine, pyroxene, and brucite; locally, mica and carbonates were also present. Raman spectroscopy distinguished antigorite and chrysotile, which could not be differentiated using XRD. Long-count, short-range XRD scans of the (110) amphibole peak showed trace amounts of amphibole in most samples. Examination of amphiboles in tailings by optical microscopy, SEM, and EPMA revealed non-fibrous amphiboles compositionally classified as edenite, magnesiohornblende, magnesiokatophorite, and pargasite. No fibrous amphibole was found in the tailings, although fibrous tremolite was identified in a sample of host rock. Knowledge of the mineralogy at the site may lead to better understanding of potential implications for human health and aid in designing a remediation plan.

Structural and phase transformation of A{sup III}B{sup V}(100) semiconductor surface in interaction with selenium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezryadin, N. N.; Kotov, G. I., E-mail: giktv@mail.ru; Kuzubov, S. V., E-mail: kuzub@land.ru

2015-03-15

Surfaces of GaAs(100), InAs(100), and GaP(100) substrates thermally treated in selenium vapor have been investigated by transmission electron microscopy and electron probe X-ray microanalysis. Some specific features and regularities of the formation of A{sub 3}{sup III}B{sub 4}{sup VI} (100)c(2 × 2) surface phases and thin layers of gallium or indium selenides A{sub 2}{sup III}B{sub 3}{sup VI} (100) on surfaces of different A{sup III}B{sup V}(100) semiconductors are discussed within the vacancy model of surface atomic structure.

Patterned low temperature copper-rich deposits using inkjet printing

NASA Astrophysics Data System (ADS)

Rozenberg, Gregor G.; Bresler, Eric; Speakman, Stuart P.; Jeynes, Chris; Steinke, Joachim H. G.

2002-12-01

A PZT piezoelectric ceramic research drop-on-demand inkjet print head operating in bend mode was used as a means of delivering a copper precursor, vinyltrimethylsilane copper (+1) hexafluoroacetylacetonate, in a controlled and placement accurate fashion. The reagent disproportionates at low temperature (<200 °C), to deposit copper on glass. These deposits are shown to be more than 90% copper by weight by electron probe microanalysis and microbeam Rutherford backscattering spectroscopy. Microscopy shows a deposit diameter and three-dimensional profile that suggests a complex deposition and conversion mechanism. Our findings represent an important step towards the manufacture of electronic devices by entirely nonlithographic means.

Application of SEM and EDX in studying biomineralization in plant tissues.

PubMed

He, Honghua; Kirilak, Yaowanuj

2014-01-01

This chapter describes protocols using formalin-acetic acid-alcohol (FAA) to fix plant tissues for studying biomineralization by means of scanning electron microscopy (SEM) and qualitative energy-dispersive X-ray microanalysis (EDX). Specimen preparation protocols for SEM and EDX mainly include fixation, dehydration, critical point drying (CPD), mounting, and coating. Gold-coated specimens are used for SEM imaging, while gold- and carbon-coated specimens are prepared for qualitative X-ray microanalyses separately to obtain complementary information on the elemental compositions of biominerals. During the specimen preparation procedure for SEM, some biominerals may be dislodged or scattered, making it difficult to determine their accurate locations, and light microscopy is used to complement SEM studies. Specimen preparation protocols for light microscopy generally include fixation, dehydration, infiltration and embedding with resin, microtome sectioning, and staining. In addition, microwave processing methods are adopted here to speed up the specimen preparation process for both SEM and light microscopy.

Effect of Cooling Rates on γ → α Transformation and Metastable States in Fe-Cu Alloys with Addition of Ni

NASA Astrophysics Data System (ADS)

Crozet, C.; Verdier, M.; Lay, S.; Antoni-Zdziobek, A.

2018-07-01

α/γ phase transformations occurring in Fe-10Cu-xNi alloys (0 ≤ x ≤ 15 in mass%) were studied using X-ray diffraction, scanning electron microscopy, electron back scattered diffraction, transmission electron microscopy and chemical analysis, combining X-ray microanalysis with energy dispersive spectrometry in the scanning electron microscope and electron microprobe analysis with wavelength dispersive spectrometry. The influence of cooling rate on the microstructure was investigated using ice-brine quenching and 2 °C/min slow cooling rate performed with dilatometry. Ni addition induces metastable transformations on cooling: massive and bainitic ferrite are formed depending on the alloy composition and cooling rate. Moreover, most of the Cu phase precipitates on cooling giving rise to a fine distribution of Cu particles in the ferrite grains. For both cooling conditions, the hardness increases with increasing Ni content and a higher hardness is obtained in the quenched alloy for each composition. The change in hardness is correlated to the effect of Ni solid solution, transformation structure and size of Cu particles.

Titanium pigmentation. An electron probe microanalysis study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dupre, A.; Touron, P.; Daste, J.

1985-05-01

A patient had an unusual pigmentary disease induced by titanium dioxide. The use of a topical cream containing titanium dioxide caused a xanthomalike appearance on the patient's penis. Electron probe microanalysis was valuable in establishing the cause of this balanitis.

Characterization of the calcification of cardiac valve bioprostheses by environmental scanning electron microscopy and vibrational spectroscopy.

PubMed

Delogne, Christophe; Lawford, Patricia V; Habesch, Steven M; Carolan, Vikki A

2007-10-01

Bioprosthetic heart valve tissue and associated calcification were studied in their natural state, using environmental scanning electron microscopy (ESEM). Energy dispersive X-ray micro-analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopy were used to characterize the various calcific deposits observed with ESEM. The major elements present in calcified valves were also analyzed by inductively coupled plasma-optical emission spectroscopy. To better understand the precursor formation of the calcific deposits, results from the elemental analyses were statistically correlated. ESEM revealed the presence of four broad types of calcium phosphate crystal morphology. In addition, two main patterns of organization of calcific deposits were observed associated with the collagen fibres. Energy dispersive X-ray micro-analysis identified the crystals observed by ESEM as salts containing mainly calcium and phosphate with ratios from 1.340 (possibly octacalcium phosphate, which has a Ca/P ratio of 1.336) to 2.045 (possibly hydroxyapatite with incorporation of carbonate and metal ion contaminants, such as silicon and magnesium, in the crystal lattice). Raman and fourier-transform infrared spectroscopy also identified the presence of carbonate and the analyses showed spectral features very similar to a crystalline hydroxyapatite spectrum, also refuting the presence of precursor phases such as beta-tricalcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate. The results of this study raised the possibility of the presence of precursor phases associated with the early stages of calcification.

New frontiers in water purification: highly stable amphopolycarboxyglycinate-stabilized Ag-AgCl nanocomposite and its newly discovered potential

NASA Astrophysics Data System (ADS)

Krutyakov, Yurii A.; Zherebin, Pavel M.; Kudrinskiy, Alexey A.; Zubavichus, Yan V.; Presniakov, Mikhail Yu; Yapryntsev, Alexey D.; Karabtseva, Anastasia V.; Mikhaylov, Dmitry M.; Lisichkin, Georgii V.

2016-09-01

A simple synthetic procedure for high-stable dispersions of porous composite Ag/AgCl nanoparticles stabilized with amphoteric surfactant sodium tallow amphopolycarboxyglycinate has been proposed for the first time. The prepared samples were characterized by UV-vis spectroscopy, x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy, small area electron diffraction (SAED), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electron probe micro-analysis. In addition, measurements (carried out at the Kurchatov synchrotron radiation source stations) of the Ag K-edge extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) spectra and XRD of the prepared nanoparticles have been performed. The obtained results suggest that small-sized Ag clusters are homogeneously distributed in the mass of the AgCl nanoparticle (~80 nm) formed during the synthesis. The Ag/AgCl dispersion demonstrates photocatalytic activity (with respect to methyl orange) and high bactericidal activity against E. coli. This activity is superior to the activity of both Ag and AgCl nanoparticles stabilized by the same surfactant. Thus, porous composite Ag/AgCl nanoparticles can be used as a multifunctional agent that is able to remove both pollutants and bacterium from water.

Imaging interactions of metal oxide nanoparticles with macrophage cells by ultra-high resolution scanning electron microscopy techniques†

PubMed Central

Plascencia-Villa, Germán; Starr, Clarise R.; Armstrong, Linda S.; Ponce, Arturo

2016-01-01

Use of engineered metal oxide nanoparticles in a plethora of biological applications and custom products has warned about some possible dose-dependent cytotoxic effects. Macrophages are key components of the innate immune system used to study possible toxic effects and internalization of different nanoparticulate materials. In this work, ultra-high resolution field emission scanning electron microscopy (FE-SEM) was used to offer new insights into the dynamical processes of interaction of nanomaterials with macrophage cells dosed with different concentrations of metal oxide nanoparticles (CeO2, TiO2 and ZnO). The versatility of FE-SEM has allowed obtaining a detailed characterization of processes of adsorption and endocytosis of nanoparticles, by using advanced analytical and imaging techniques on complete unstained uncoated cells, including secondary electron imaging, high-sensitive backscattered electron imaging, X-ray microanalysis and stereoimaging. Low voltage BF/DF-STEM confirmed nanoparticle adsorption and internalization into endosomes of CeO2 and TiO2, whereas ZnO develop apoptosis after 24 h of interaction caused by dissolution and invasion of cell nucleus. Ultra-high resolution scanning electron microscopy techniques provided new insights into interactions of inorganic nanoparticles with macrophage cells with high spatial resolution. PMID:23023106

Phase constitution characteristics of the Fe-Al alloy layer in the HAZ of calorized steel pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Yajiang; Zou Zengda; Wei Xing

1997-09-01

Mechanical properties of the welding region and phase constitution characteristics in the iron-aluminum (Fe-Al) alloy layer of calorized steel pipes were researched by means of metallography, which included the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe microanalysis (EPMA) and an X-ray diffractometer. Experimental results indicated that the Fe-Al alloy layer of calorized steel pipe was mainly composed of an FeAl phase, an Fe{sub 3}Al phase and an {alpha}-Fe(Al) solid solution, and the microhardness in the Fe-Al coating was 600--310 HM from the surface layer to the inside. There were no higher aluminum content phases, suchmore » as brittle FeAl{sub 2}, Fe{sub 2}Al{sub 5} and FeAl{sub 3}. By controlling the aluminizing process parameters, the ability to bear deformation and weld-ability of the calorized steel pipe were remarkably improved.« less

Novel preparation of highly photocatalytically active copper chromite nanostructured material via a simple hydrothermal route

PubMed Central

Beshkar, Farshad; Zinatloo-Ajabshir, Sahar; Bagheri, Samira; Salavati-Niasari, Masoud

2017-01-01

Highly photocatalytically active copper chromite nanostructured material were prepared via a novel simple hydrothermal reaction between [Cu(en)2(H2O)2]Cl2 and [Cr(en)3]Cl3.3H2O at low temperature, without adding any pH regulator or external capping agent. The as-synthesized nanostructured copper chromite was analyzed by transmission electron microscopy (TEM), UV–vis diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. Results of the morphological investigation of the as-synthesized products illustrate that the shape and size of the copper chromite depended on the surfactant sort, reaction duration and temperature. Moreover, the photocatalytic behavior of as-obtained copper chromite was evaluated by photodegradation of acid blue 92 (anionic dye) as water pollutant. PMID:28582420

Rapid and solvent-free solid-state synthesis and characterization of Zn3V2O8 nanostructures and their phenol red aqueous solution photodegradation

NASA Astrophysics Data System (ADS)

Mazloom, Fatemeh; Masjedi-Arani, Maryam; Salavati-Niasari, Masoud

2017-08-01

Zinc vanadate (Zn3V2O8) nanostructures have been successfully synthesized via simple, rapid and solvent-free solid-state method by using different complex precursors of Zn and NH4VO3 as novel starting materials. Effects of various zinc (II) Schiff base complex precursors and calcination temperatures were investigated to reach optimum condition. It was found that particle size and optical property of the as-prepared products could be greatly influenced via these parameters. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Photoluminescence and ultraviolet-visible (UV-Vis) spectroscopy. The photocatalytic activity of zinc vanadate nano and bulk structures were compared by degradation of phenol red aqueous solution.

Cryo-Scanning Electron Microscopy of Captured Cirrus Ice Particles

NASA Astrophysics Data System (ADS)

Magee, N. B.; Boaggio, K.; Bandamede, M.; Bancroft, L.; Hurler, K.

2016-12-01

We present the latest collection of high-resolution cryo-scanning electron microscopy images and microanalysis of cirrus ice particles captured by high-altitude balloon (ICE-Ball, see abstracts by K. Boaggio and M. Bandamede). Ice particle images and sublimation-residues are derived from particles captured during approximately 15 balloon flights conducted in Pennsylvania and New Jersey over the past 12 months. Measurements include 3D digital elevation model reconstructions of ice particles, and associated statistical analyses of entire particles and particle sub-facets and surfaces. This 3D analysis reveals that morphologies of most ice particles captured deviate significantly from ideal habits, and display geometric complexity and surface roughness at multiple measureable scales, ranging from 100's nanometers to 100's of microns. The presentation suggests potential a path forward for representing scattering from a realistically complex array of ice particle shapes and surfaces.

The microstructure and formation of duplex and black plessite in iron meteorites

NASA Technical Reports Server (NTRS)

Zhang, J.; Williams, D. B.; Goldstein, J. I.

1993-01-01

Two of the most common plessite structures, duplex and black plessite, in the taenite region of the Windmanstatten pattern of two iron meteorites (Grant and Carlton) are characterized using high-resolution electron microscopy and microanalysis techniques. Two types of gamma precipitates, found in the duplex plessite and black plessite regions, respectively, are identified, and their morphologies are described. The formation of the plessite structure is discussed using the information obtained in this study and results of a parallel investigation of decomposed martensitic Fe-Ni laboratory alloys.

Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC-Co Hard Alloys

NASA Astrophysics Data System (ADS)

Linnik, S. A.; Gaidaichuk, A. V.; Okhotnikov, V. V.

2018-02-01

The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC-Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

Forensic microanalysis of Manhattan Project legacy radioactive wastes in St. Louis, MO.

PubMed

Kaltofen, Marco; Alvarez, Robert; Hixson, Lucas W

2018-06-01

Radioactive particulate matter (RPM) in St Louis, MO, area surface soils, house dusts and sediments was examined by scanning electron microscopy with energy dispersive X-ray analysis. Analyses found RPM containing 238 U and decay products (up to 46 wt%), and a distinct second form of RPM containing 230 Th and decay products (up to 15.6 wt%). The SEM-EDS analyses found similar RPM in Manhattan Project-era radioactive wastes and indoor dusts in surrounding homes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Analytical electron microscopy as a powerful tool in plant cell biology: examples using electron energy loss spectroscopy and X-ray microanalysis.

PubMed

Lichtenberger, O; Neumann, D

1997-08-01

Energy filtering transmission electron microscopy in combination with energy dispersive X-ray analysis (EDX) and quantumchemical calculations opens new possibilities for elemental and bone analysis at the ultrastructural level. The possibilities and limitations of these methods, applied to botanical samples, are discussed and some examples are given. Ca-oxalate crystals in plant cell vacuoles show a specific C K-edge in the electron energy loss spectrum (EELS), which allows a more reliable identification than light microscopical or cytochemical methods. In some dicots crystalline inclusions can be observed in different cell compartments, which are identified as silicon dioxide or calcium silicate by the fine structure of the Si L2,3-edge. Their formation is discussed on the basis of EEL-spectra and quantumchemical calculations. Examples concerning heavy metal detoxification are given for some tolerant plants. In Minuartia Zn is bound as Zn-silicate in cell walls; Armeria accumulates Cu in leaf idioblasts by chelation with phenolic compounds and Cd is precipitated as CdS/phytochelatin-complexes in tomato.

Electron-Excited X-Ray Microanalysis at Low Beam Energy: Almost Always an Adventure!

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2016-08-01

Scanning electron microscopy with energy-dispersive spectrometry has been applied to the analysis of various materials at low-incident beam energies, E 0≤5 keV, using peak fitting and following the measured standards/matrix corrections protocol embedded in the National Institute of Standards and Technology Desktop Spectrum Analyzer-II analytical software engine. Low beam energy analysis provides improved spatial resolution laterally and in-depth. The lower beam energy restricts the atomic shells that can be ionized, reducing the number of X-ray peak families available to the analyst. At E 0=5 keV, all elements of the periodic table except H and He can be measured. As the beam energy is reduced below 5 keV, elements become inaccessible due to lack of excitation of useful characteristic X-ray peaks. The shallow sampling depth of low beam energy microanalysis makes the technique more sensitive to surface compositional modification due to formation of oxides and other reaction layers. Accurate and precise analysis is possible with the use of appropriate standards and by accumulating high count spectra of unknowns and standards (>1 million counts integrated from 0.1 keV to E 0).

Seawater spray injury to Quercus acutissima leaves: crystal deposition, stomatal clogging, and chloroplast degeneration.

PubMed

Kim, Ki Woo; Koo, Kyosang; Kim, Pan-Gi

2011-05-01

Effects of seawater spray on leaf structure were investigated in Quercus acutissima by electron microscopy and X-ray microanalysis. Two-year-old seedlings of Q. acutissima were sprayed with seawater and kept in a greenhouse maintained at 25°C. The most recognizable symptoms of seawater-sprayed seedlings included leaf necrosis, crystal deposition, stomatal clogging, and chloroplast degeneration. Field emission scanning electron microscopy revealed that the leaf surface was covered with additional layers of remnants of seawater spray. Composed of sodium and chloride, cube-shaped crystals (halite) were prevalently found on trichomes and epidermis, and formed aggregates. Meanwhile, wedge-shaped crystals were deposited on epidermis and consisted of calcium and sulfur. As a result of stomatal clogging by crystal deposition on the abaxial surface, it was conceivable that plant respiration became severely hampered. Transmission electron microscopy showed degenerated cytoplasm of seawater-sprayed leaves. It was common to observe severe plasmolysis and disrupted chloroplasts with a reduced number of thylakoids in grana. These results indicate that foliar applications of seawater were sufficient to induce necrosis of Q. acutissima seedlings as an abiotic disturbance factor. Copyright © 2010 Wiley-Liss, Inc.

A Scan through the History of STEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pennycook, Stephen J

2011-01-01

The development of Scanning Transmission Electron Microscopy (STEM) is outlined from the first developments by Baron Manfred von Ardenne, through the first successful field emission gun STEM by Albert Crewe and his collaborators, to its widespread application today in the era of aberration correction. The review focuses on the development and understanding of incoherent imaging and electron energy loss spectroscopy at atomic resolution and will not include details on microanalysis, low loss imaging, or specialized modes such as cathodoluminescence. Although it attempts to cover all the major advances in approximately chronological order, undoubtedly there are omissions and an overemphasis onmore » developments that the author is most familiar with from his own history.« less

X-Ray Microanalysis and Electron Energy Loss Spectrometry in the Analytical Electron Microscope: Review and Future Directions

NASA Technical Reports Server (NTRS)

Goldstein, J. I.; Williams, D. B.

1992-01-01

This paper reviews and discusses future directions in analytical electron microscopy for microchemical analysis using X-ray and Electron Energy Loss Spectroscopy (EELS). The technique of X-ray microanalysis, using the ratio method and k(sub AB) factors, is outlined. The X-ray absorption correction is the major barrier to the objective of obtaining I% accuracy and precision in analysis. Spatial resolution and Minimum Detectability Limits (MDL) are considered with present limitations of spatial resolution in the 2 to 3 microns range and of MDL in the 0.1 to 0.2 wt. % range when a Field Emission Gun (FEG) system is used. Future directions of X-ray analysis include improvement in X-ray spatial resolution to the I to 2 microns range and MDL as low as 0.01 wt. %. With these improvements the detection of single atoms in the analysis volume will be possible. Other future improvements include the use of clean room techniques for thin specimen preparation, quantification available at the I% accuracy and precision level with light element analysis quantification available at better than the 10% accuracy and precision level, the incorporation of a compact wavelength dispersive spectrometer to improve X-ray spectral resolution, light element analysis and MDL, and instrument improvements including source stability, on-line probe current measurements, stage stability, and computerized stage control. The paper reviews the EELS technique, recognizing that it has been slow to develop and still remains firmly in research laboratories rather than in applications laboratories. Consideration of microanalysis with core-loss edges is given along with a discussion of the limitations such as specimen thickness. Spatial resolution and MDL are considered, recognizing that single atom detection is already possible. Plasmon loss analysis is discussed as well as fine structure analysis. New techniques for energy-loss imaging are also summarized. Future directions in the EELS technique will be the development of new spectrometers and improvements in thin specimen preparation. The microanalysis technique needs to be simplified and software developed so that the EELS technique approaches the relative simplicity of the X-ray technique. Finally, one can expect major improvements in EELS imaging as data storage and processing improvements occur.

Evaluating the Performance of a Commercial Silicon Drift Detector for X-ray Microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenik, Edward A

2011-01-01

Silicon drift detectors (SDDs) are rapidly becoming the energy dispersive spectrometer (EDS) of choice, especially for scanning electron microscopy x-ray microanalysis. The complementary features of large active areas (i.e., high collection angle) and high count rate capability of these detector contribute to their popularity, as well as the absence of liquid nitrogen cooling and good energy resolution of these detectors. The performance of an EDAX Apollo 40 SDD on a JEOL 6500F SEM is discussed. The larger detector resulted in an significant increase (~3.5x) in geometric collection efficiency compared to the original 10mm2 Si(Li) detector that it replaced. The SEMmore » can provide high beam currents (up to 200nA in some conditions) at small probe diameters. The high count rate capability of the SDD and the high current capability of the SEM compliment each other and provide excellent EDS analytical capabilities for both single point and spectrum imaging applications.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ovcharov, A. V.; Karateev, I. A.; Mikhutkin, A. A.

The surface microstructure of Ni–W alloy tapes, which are used as substrates to form films of high-temperature superconductors and photovoltaic devices, has been studied. Several samples of a Ni{sub 95}W{sub 5} tape (Evico) annealed under different conditions were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, electron diffraction, and electron energy-loss spectroscopy. NiWO{sub 4} precipitates are found on the surface of annealed samples. The growth of precipitates at a temperature of 950°C is accompanied by the formation of pores on the surface or under an oxide film. Depressions with a wedge-shaped profile are found at the grain boundaries. Annealing inmore » a reducing atmosphere using a specially prepared chamber allows one to form a surface free of nickel tungstate precipitates.« less

Postvaccinal sarcomas in the cat: epidemiology and electron probe microanalytical identification of aluminum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendrick, M.J.; Goldschmidt, M.H.; Shofer, F.S.

1992-10-01

An increase in fibrosarcomas in a biopsy population of cats in the Pennsylvania area appears to be related to the increased vaccination of cats following enactment of a mandatory rabies vaccination law. The majority of fibrosarcomas arose in sites routinely used by veterinarians for vaccination, and 42 of 198 tumors were surrounded by lymphocytes and macrophages containing foreign material identical to that previously described in postvaccinal inflammatory injection site reactions. Some of the vaccines used have aluminum-based adjuvants, and macrophages surrounding three tumors contained aluminum oxide identified by electron probe microanalysis and imaged by energy-filtered electron microscopy. Persistence of inflammatorymore » and immunological reactions associated with aluminum may predispose the cat to a derangement of its fibrous connective tissue repair response, leading to neoplasia.« less

Standards for electron probe microanalysis of silicates prepared by convenient method

NASA Technical Reports Server (NTRS)

Walter, L. S.

1966-01-01

Standard compositions suitable for electron probe microanalysis of various silicates are prepared by coprecipitation of specified salts with colloidal silica to form a gel which is decomposed into a powdered oxide mixture and compressed into thin pellets. These pellets of predetermined standard are compared with a silicate sample to determine its composition.

Thermal stability of intermetallic phases in Fe-rich Fe-Cr-Ni-Mo alloys

DOE PAGES

Yang, Ying; Tan, Lizhen; Busby, Jeremy T.

2015-06-12

Understanding the stability of precipitate phases in the Fe-rich Fe-Cr-Ni-Mo alloys is critical to the alloy design and application of Mo-containing Austenitic steels. Coupled with thermodynamic modeling, stability of the chi and Laves phases in two Fe-Cr-Ni-Mo alloys were investigated at 1000, 850 and 700 °C for different annealing time. The morphologies, compositions and crystal structures of the matrix and precipitate phases were carefully examined by Scanning Electron Microscopy, Electron Probe Microanalysis, X-ray diffraction and Transmission Electron Microscopy. The two key findings resulted from this work. One is that the chi phase is stable at high temperature and transformed intomore » the Laves phase at low temperature. The other is that both the chi and Laves phases have large solubilites of Cr, Mo and Ni, among which the Mo solubility has a major role on the relative stability of the precipitate phases. The developed thermodynamic models were then applied to evaluating the Mo effect on the stability of precipitate phases in AISI 316 and NF709 alloys.« less

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

NASA Astrophysics Data System (ADS)

Ward, Antony J.; Pujari, Ajit A.; Costanzo, Lorenzo; Masters, Anthony F.; Maschmeyer, Thomas

2011-12-01

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%.

Analysis of pigments from Roman wall paintings found in the "agro centuriato" of Julia Concordia (Italy).

PubMed

Mazzocchin, Gian-Antonio; Del Favero, Michela; Tasca, Giovanni

2007-09-01

The analysis of wall painting fragments recovered in the "agro centuriato" of Julia Concordia has been carried out by using Scanning Electron Microscopy equipped with an EDS microanalysis detector (SEM-EDS), Infrared Spectroscopy (FTIR) and X-Ray powder Diffraction (XRD). The pigments used have been identified and the data obtained suggest the presence of three rustic villas richly decorated also with Egyptian blue. The presence of white of aragonite suggest that these villas were decorated during the Imperial Age, in agreement with the recovery of high quality materials and a bronze statue.

PREFACE: EMAS 2011: 12th European Workshop on Modern Developments in Microbeam Analysis

NASA Astrophysics Data System (ADS)

Brisset, François; Dugne, Olivier; Robaut, Florence; Lábár, János L.; Walker, Clive T.

2012-03-01

This volume of IOP Conference Series: Materials Science and Engineering contains papers from the 12th Workshop of the European Microbeam Analysis Society (EMAS) on Modern Developments and Applications in Microbeam Analysis, which took place from the 15-19 May 2011 in the Angers Congress Centre, Angers, France. The primary aim of this series of workshops is to assess the state-of-the-art and reliability of microbeam analysis techniques. The workshops also provide a forum where students and young scientists starting out on a career in microbeam analysis can meet and discuss with the established experts. The workshops have a very specific format comprising invited plenary lectures by internationally recognized experts, poster presentations by the participants and round table discussions on the key topics led by specialists in the field. This workshop was organized in collaboration with GN-MEBA - Groupement National de Microscopie Electronique à Balayage et de microAnalysis, France. The technical programme included the following topics: the limits of EPMA, new techniques, developments and concepts in microanalysis, microanalysis in the SEM, and new and less common applications of micro- and nanoanalysis. As at previous workshops there was also a special oral session for young scientists. The best presentation by a young scientist was awarded with an invitation to attend the 2012 Microscopy and Microanalysis meeting at Phoenix, Arizona. The prize went to Pierre Burdet, of the Federal Institute of Technology of Lausanne (EPFL), for his talk entitled '3D EDS microanalysis by FIB-SEM: enhancement of elemental quantification'. The continuing relevance of the EMAS workshops and the high regard in which they are held internationally can be seen from the fact that 74 posters from 18 countries were on display at the meeting, and that the participants came from as far away as Japan, Canada and the USA. A selection of participants with posters were invited to give a short oral presentation of their work in three dedicated sessions. The prize for the best poster was an invitation to participate in the 22nd Australian Conference on Microscopy and Microanalysis (ACMM 22) at Perth, Western Australia. The prize was awarded to G Samardzija of the Jozef Stefan Institute, Ljubljana, for the poster entitled: 'EPMA-WDS quantitative compositional analysis of barium titanate ceramics doped with cerium'. This proceedings volume contains the full texts of 5 of the invited plenary lectures and of 23 papers on related topics originating from the posters presented at the workshop. All the papers have been subjected to peer review by a least two referees. January 2012 Acknowledgements On behalf of the European Microbeam Analysis Society I would like to thank all the invited speakers, session chairs and members of the discussion panels for making the meeting such a great success. Special thanks go to François Brisset and Luc Van't dack who directed the organisation of the workshop giving freely of their time and talents. As was the case for previous workshops, the EMAS board in corpore was responsible for the scientific programme. The technical exhibition, which occupied 130 sq.m of floor space, was outstanding. It was very encouraging to see new instruments on display, including a FEG electron microprobe as a first worldwide presentation. Moreover, almost all the companies that exhibited provided financial support, either by sponsoring an event or by advertising. Below, in alphabetical order, is a list of exhibiting companies and sponsors of the workshop: Ametek GmbH, Edax Business UnitGN-MEBA Bruker Nano GmbHJeol (Europe) SAS CamecaL'Oréal, Direction Générale Recherche et Innovation Carl Zeiss NTSNanoMEGAS sprl Commissariat à l'Energie AtomiqueOxford Instruments SAS European Institute for Transuranium Elements (Germany)Probe Software, Inc. ElexienceSAMx FEI CompanyTarget-Messtechnik Fondis Electronic SAThermo Fisher Scientific Gatan (France) Clive T. Walker EMAS President

Formation of Porous Germanium Layers by Silver-Ion Implantation

NASA Astrophysics Data System (ADS)

Stepanov, A. L.; Vorob'ev, V. V.; Nuzhdin, V. I.; Valeev, V. F.; Osin, Yu. N.

2018-04-01

We propose a method for the formation of porous germanium ( P-Ge) layers containing silver nanoparticles by means of high-dose implantation of low-energy Ag+ ions into single-crystalline germanium ( c-Ge). This is demonstrated by implantation of 30-keV Ag+ ions into a polished c-Ge plate to a dose of 1.5 × 1017 ion/cm2 at an ion beam-current density of 5 μA/cm2. Examination by high-resolution scanning electron microscopy (SEM), atomic-force microscopy (AFM), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) microanalysis, and reflection high-energy electron diffraction (RHEED) showed that the implantation of silver ions into c-Ge surface led to the formation of a P-Ge layer with spongy structure comprising a network of interwoven nanofibers with an average diameter of ˜10-20 nm Ag nanoparticles on the ends of fibers. It is also established that the formation of pores during Ag+ ion implantation is accompanied by effective sputtering of the Ge surface.

Intraocular Lens Opacification After Endothelial Keratoplasty as Analyzed by Environmental Scanning Electron Microscopy.

PubMed

Verdaguer, Paula; Gris, Oscar; Casaroli-Marano, Ricardo P; Elies, Daniel; Muñoz-Gutierrez, Gerardo; Güell, Jose L

2015-08-01

To describe a case of hydrophilic intraocular lens (IOL) opacification based on IOL analysis after Descemet stripping automated endothelial keratoplasty. A 60-year-old woman had uneventful phacoemulsification after the implantation of a hydrophilic IOL (Akreos-Adapt; Bausch & Lomb) into both eyes. Because of postoperative corneal decompensation in the right eye, 2 Descemet stripping automated endothelial keratoplasty operations were performed within 1 year. After the second procedure, the graft was not well attached, requiring an intracameral injection of air on day 3. After 1 year, opacification was observed on the superior 2/3 of the anterior surface of the IOL, along with a significant decrease in visual acuity. The IOL was explanted 6 months after the opacification. Environmental scanning electron microscopy followed by x-ray microanalysis revealed an organic biofilm on the surface of the IOL. To our knowledge, this is the first reported case in which the material deposited on the lens is organic rather than calcific.

Green Synthesis and Characterization of SmVO4 Nanoparticles in the Presence of Carbohydrates As Capping Agents with Investigation of Visible-Light Photocatalytic Properties

NASA Astrophysics Data System (ADS)

Eghbali-Arani, Mohammad; Sobhani-Nasab, Ali; Rahimi-Nasrabadi, Mehdi; Pourmasoud, Saeid

2018-03-01

SmVO4 nanoparticles were synthesized through a fast and simple procedure (green method). The effects of three parameters including temperature, type of capping agent, and concentration on the size and morphology behavior of SmVO4 nanoparticles were explored. The analysis of SmVO4 nanoparticles was performed through some techniques including, Fourier transform infrared spectroscopy, x-ray diffraction, energy dispersive x-ray microanalysis, scanning electron microscopy, transmission electron microscopy, thermogravimetry, differential thermal analysis, ultraviolet-visible spectroscopy, and vibrating sample magnetometers. The study of photocatalytic behaviour of the SmVO4 nanoparticles in various conditions has been carried out. The impacts of different factors such as dosage, grain size, and kind of pollutant (methylene blue = MB and methyl orange = MO) on the photocatalytic property of SmVO4 nanoparticles were assessed. The photocatalytic activities of SmVO4 catalysts were studied for the degradation of dye under visible light (λ > 400 nm).

Improvement in the Characterization of the 2099 Al-Li Alloy by FE-SEM

NASA Astrophysics Data System (ADS)

Brodusch, Nicolas; Trudeau, Michel L.; Michaud, Pierre; Brochu, Mathieu; Rodrigue, Lisa; Boselli, Julien; Gauvin, Raynald

This paper describes how state-of-the-art Field-Emission Scanning Electron Microscopy (FE-SEM) can contribute to the characterization of the 2099 aluminum-lithium alloy, and metallic alloys in general. Investigations were carried out on bulk and thinned samples. BSE imaging at 3kV and STEM imaging at 30kV along with highly efficient microanalysis permitted to correlate experimental and expected structures. Although our results confirm previous studies, this work points out possible substitutions of Mg and Zn with Li, Al and Cu in the T1 precipitates. Zinc and magnesium are also present in "rice grain" shaped precipitates at the grain boundaries. The versatility of the FE-SEM is highlighted in that it can provide information at the macro and micro scales with relevant details. Its ability to probe the distribution of precipitates from nano-to micro-sizes throughout the matrix makes Field-Emission Scanning Electron Microscopy a suitable technique for the characterization of metallic alloys.

Chemical Imaging Analysis of Environmental Particles Using the Focused Ion Beam/Scanning Electron Microscopy Technique. Microanalysis Insights into Atmospheric Chemistry of Fly Ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Haihan; Grassian, Vicki H.; Saraf, Laxmikant V.

2012-11-08

Airborne fly ash from coal combustion may represent a source of bioavailable iron (Fe) in the open ocean. However, few studies have been made focusing on Fe speciation and distribution in coal fly ash. In this study, chemical imaging of fly ash has been performed using a dual-beam FIB/SEM (focused ion beam/scanning electron microscope) system for a better understanding of how simulated atmospheric processing modify the morphology, chemical compositions and element distributions of individual particles. A novel approach has been applied for cross-sectioning of fly ash specimen with a FIB in order to explore element distribution within the interior ofmore » individual particles. Our results indicate that simulated atmospheric processing causes disintegration of aluminosilicate glass, a dominant material in fly ash particles. Aluminosilicate-phase Fe in the inner core of fly ash particles is more easily mobilized compared with oxide-phase Fe present as surface aggregates on fly ash spheres. Fe release behavior depends strongly on Fe speciation in aerosol particles. The approach for preparation of cross-sectioned specimen described here opens new opportunities for particle microanalysis, particular with respect to inorganic refractive materials like fly ash and mineral dust.« less

Effect of Gold on the Microstructural Evolution and Integrity of a Sintered Silver Joint

NASA Astrophysics Data System (ADS)

Muralidharan, Govindarajan; Leonard, Donovan N.; Meyer, Harry M.

2017-07-01

There is a need for next-generation, high-performance power electronic packages and systems employing wide-bandgap devices to operate at high temperatures in automotive and electric grid applications. Sintered silver joints are currently being evaluated as an alternative to Pb-free solder joints. Of particular interest is the development of joints based on silver paste consisting of nano- or micron-scale particles that can be processed without application of external pressure. The microstructural evolution at the interface of a pressureless-sintered silver joint formed between a SiC die with Ti/Ni/Au metallization and an active metal brazed (AMB) substrate with Ag metallization at 250°C has been evaluated using scanning electron microscopy (SEM), x-ray microanalysis, and x-ray photoelectron spectroscopy (XPS). Results from focused ion beam (FIB) cross-sections show that, during sintering, pores in the sintered region near to the Au layer tend to be narrow and elongated with long axis oriented parallel to the interface. Further densification results in formation of many small, relatively equiaxed pores aligned parallel to the interface, creating a path for easy crack propagation. X-ray microanalysis results confirm interdiffusion between Au and Ag and that a region with poor mechanical strength is formed at the edge of this region of interdiffusion.

Electron microscopy and forensic practice

NASA Astrophysics Data System (ADS)

Kotrlý, Marek; Turková, Ivana

2013-05-01

Electron microanalysis in forensic practice ranks among basic applications used in investigation of traces (latents, stains, etc.) from crime scenes. Applying electron microscope allows for rapid screening and receiving initial information for a wide range of traces. SEM with EDS/WDS makes it possible to observe topography surface and morphology samples and examination of chemical components. Physical laboratory of the Institute of Criminalistics Prague use SEM especially for examination of inorganic samples, rarely for biology and other material. Recently, possibilities of electron microscopy have been extended considerably using dual systems with focused ion beam. These systems are applied mainly in study of inner micro and nanoparticles , thin layers (intersecting lines in graphical forensic examinations, analysis of layers of functional glass, etc.), study of alloys microdefects, creating 3D particles and aggregates models, etc. Automated mineralogical analyses are a great asset to analysis of mineral phases, particularly soils, similarly it holds for cathode luminescence, predominantly colour one and precise quantitative measurement of their spectral characteristics. Among latest innovations that are becoming to appear also at ordinary laboratories are TOF - SIMS systems and micro Raman spectroscopy with a resolution comparable to EDS/WDS analysis (capable of achieving similar level as through EDS/WDS analysis).

Today's and Tomorrow's Instruments.

PubMed

Conty, Claude

2001-03-01

This article will discuss the importance of Raimond Castaing's thesis on the genesis of a nondestructive and truly quantitative microanalytical method that assisted the scientific community in moving forward in the development of microanalytical instruments. I will also share with you my recollection of the decades of improvement in the electron probe microanalyzer (EPMA), that has allowed us to reach our present level of instrument sophistication, and I will explore with you my thoughts on the future evolution of this technique. To conclude, I will present the current status of related microanalysis techniques developed under Castaing in Orsay in the 1960s, as Castaing's interest in microanalysis was not limited to electron probe microanalysis alone.

Confocal laser scanning microscopy coupled to a spectrofluorometric detector as a rapid tool for determining the in vivo effect of metals on phototrophic bacteria.

PubMed

Burnat, Mireia; Diestra, Elia; Esteve, Isabel; Solé, Antonio

2010-01-01

In this paper, we determine for the first time the in vivo effect of heavy metals in a phototrophic bacterium. We used Confocal Laser Scanning Microscopy coupled to a spectrofluorometric detector as a rapid technique to measure pigment response to heavy-metal exposure. To this end, we selected lead and copper (toxic and essential metals) and Microcoleus sp. as the phototrophic bacterium because it would be feasible to see this cyanobacterium as a good biomarker, since it covers large extensions of coastal sediments. The results obtained demonstrate that, while cells are still viable, pigment peak decreases whereas metal concentration increases (from 0.1 to 1 mM Pb). Pigments are totally degraded when cultures were polluted with lead and copper at the maximum doses used (25 mM Pb(NO(3))(2) and 10 mM CuSO(4)). The aim of this study was also to identify the place of metal accumulation in Microcoleus cells. Element analysis of this cyanobacterium in the above mentioned conditions determined by Energy Dispersive X-ray microanalysis (EDX) coupled to Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), shows that Pb (but not Cu) accumulates externally and internally in cells.

Indigenous Carbonaceous Matter in the Nakhla Mars Meteorite

NASA Technical Reports Server (NTRS)

Clemett, S. J.; Thomas-Keprta, K. L.; Rahman, Z.; Le, L.; Wentworth, S. J.; Gibson, E. K.; McKay, D. S.

2016-01-01

Detailed microanalysis of the Martian meteorite Nakhla has shown there are morphologically distinct carbonaceous features spatially associated with low-T aqueous alteration phases including salts and id-dingsite. A comprehensive suite of analytical instrumentation including optical microscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, focused ion beam (FIB) microscopy, transmission electron microscopy (TEM), two-step laser mass spectrometry (mu-L(sup 2)MS), laser mu-Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nanoscale secondary ion mass spectrometry (NanoSIMS) are being used to characterize the carbonaceous matter and host mineralogy. The search for carbonaceous matter on Mars has proved challenging. Viking Landers failed to unambiguously detect simple organics at either of the two landing sites although the Martian surface is estimated to have acquired at least 10(exp15) kg of C as a consequence of meteoritic accretion over the last several Ga. The dearth of organics at the Martian surface has been attributed to various oxidative processes including UV photolysis and peroxide activity. Consequently, investigations of Martian organics need to be focused on the sub-surface regolith where such surface processes are either severely attenuated or absent. Fortuitously since Martian meteorites are derived from buried regolith materials they provide a unique opportunity to study Martian organic geochemistry.

Scanning electron microscopy/energy dispersive spectrometry fixedbeam or overscan x-ray microanalysis of particles can miss the real structure: x-ray spectrum image mapping reveals the true nature

NASA Astrophysics Data System (ADS)

Newbury, Dale E.; Ritchie, Nicholas W. M.

2013-05-01

The typical strategy for analysis of a microscopic particle by scanning electron microscopy/energy dispersive spectrometry x-ray microanalysis (SEM/EDS) is to use a fixed beam placed at the particle center or to continuously overscan to gather an "averaged" x-ray spectrum. While useful, such strategies inevitably concede any possibility of recognizing microstructure within the particle, and such fine scale structure is often critical for understanding the origins, behavior, and fate of particles. Elemental imaging by x-ray mapping has been a mainstay of SEM/EDS analytical practice for many years, but the time penalty associated with mapping with older EDS technology has discouraged its general use and reserved it more for detailed studies that justified the time investment. The emergence of the high throughput, high peak stability silicon drift detector (SDD-EDS) has enabled a more effective particle mapping strategy: "flash" x-ray spectrum image maps can now be recorded in seconds that capture the spatial distribution of major (concentration, C > 0.1 mass fraction) and minor (0.01 <= C <= 0.1) constituents. New SEM/SDD-EDS instrument configurations feature multiple SDDs that view the specimen from widely spaced azimuthal angles. Multiple, simultaneous measurements from different angles enable x-ray spectrometry and mapping that can minimize the strong geometric effects of particles. The NIST DTSA-II software engine is a powerful aid for quantitatively analyzing EDS spectra measured individually as well as for mapping information (available free for Java platforms at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).

Scanning electron microscopy study of new bone formation following small and large defects preserved with xenografts supplemented with pamidronate-A pilot study in Fox-Hound dogs at 4 and 8 weeks.

PubMed

Lozano-Carrascal, Naroa; Satorres-Nieto, Marta; Delgado-Ruiz, Rafael; Maté-Sánchez de Val, José Eduardo; Gehrke, Sergio Alexandre; Gargallo-Albiol, Jorge; Calvo-Guirado, José Luis

2017-01-01

The aim of the present study was to evaluate the feasibility of SEM and EDX microanalysis on evaluating the effect of porcine xenografts (MP3 ® ) supplemented with pamidronate during socket healing. Mandibular second premolars (P2) and first molars (M1) were extracted from six Beagle dogs. P2 were categorized as small defects (SD) and M1 as large defects (LD). Four random groups were created: SC (small control defects with MP3 ® ), ST (small test defects MP3 ® +pamidronate), LC (large control defects with MP3 ® ), and LT (large test defects MP3 ® +pamidronate). At four and eight weeks of healing the samples were evaluated fisically through scanning electron microscopy (SEM), and chemical element mapping was carried out by Energy dispersive X-ray spectroscopy (EDX). After four weeks of healing, SEM and EDX analysis revealed more mineralized bone in ST and LT groups compared with control groups (p<0.05). After eight weeks, Ca/P ratios were slightly higher for small defects (groups SC and ST); in SEM description, in both control and test groups, trabecular bone density was similar to the adjacent mineralized cortical bone. Within the limitations of this experimental study, SEM description and EDX elemental microanalysis have demonstrated to be useful techniques to assess bone remodelling of small and large defects. Both techniques show increased bone formation in test groups (MP3 ® modified with pamidronate) after four and eight weeks of healing. Copyright © 2016 Elsevier GmbH. All rights reserved.

Detection of secondary phases in duplex stainless steel by magnetic force microscopy and scanning Kelvin probe force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramírez-Salgado, J.; Domínguez-Aguilar, M.A., E-mail: madoming@imp.mx; Castro-Domínguez, B.

2013-12-15

The secondary phase transformations in a commercial super duplex stainless steel were investigated by micro-chemical analyses and high resolution scanning probe microscopy. Energy dispersive X-ray and electron probe detected ferrite and austenite as well as secondary phases in unetched aged duplex stainless steel type 25Cr-7Ni-3Mo. Volta potential indicated that nitride and sigma appeared more active than ferrite, while secondary austenite and austenite presented a nobler potential. Reversal order in nobility is thought to be attributable to the potential ranking provided by oxide nature diversity as a result of secondary phase surface compositions on steel. After eutectoid transformation, secondary austenite wasmore » detected by electron probe microanalysis, whereas atomic force microscopy distinguished this phase from former austenite by image contrast. Magnetic force microscopy revealed a “ghosted” effect on the latter microstructure probably derived from metal memory reminiscence of mechanical polishing at passivity and long range magnetic forces of ferrite phase. - Highlights: • Nobility detection of secondary phases by SKPFM in DSS particles is not a straightforward procedure. • As Volta potential and contrast are not always consistent SKPFM surface oxides is thought played an important role in detection. • AFM distinguished secondary austenite from former austenite by image contrast though SEM required EPMA.« less

Structure, Microsegregation, and Precipitates of an Alloy 690 ESR Ingot in Industrial Scale

NASA Astrophysics Data System (ADS)

Wang, Min; Zha, Xiangdong; Gao, Ming; Ma, Yingche; Liu, Kui; Li, Yiyi

2015-11-01

The structure, interdendritic, and intergranular segregation, and precipitates of an Alloy 690 electro-slag remelting (ESR) ingot in commercial scale (3t) were investigated by the optical microscopy, electroprobe microanalysis, scanning electron microscopy, and transmission electron microscopy (TEM) techniques. The results indicate that the central longitudinal section of the ESR ingot comprised the ramp-up, steady-state, and hot-top regions, which could be easily distinguished from each other through the macrostructures of them. In the interdendritic area, Cr and Ti were enriched, while Ni and Fe were depleted, and the nominal segregation indexes ( ζ i = C 0 i / C interdendritic i ) of Ti, Cr, and Ni were 0.40, 0.91, and 1.04, respectively, in the hot-top region where suffered the severest segregation. Nitrides, principally precipitated between dendrites, were identified as TiN by TEM and EDS. The morphology, size distribution, and volume fraction of them were determined as well. In terms of the intergranular area, Cr and C coexisted, while Ni and Fe were depleted. And the dendrite-like carbides continuously distributed on the interface between grains, which were identified as M23C6 by the selected area diffraction pattern.

The reserpinized rat in the study of cystic fibrosis: x-ray microanalysis of submandibular gland and pancreas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roomans, G.M.; Wei, X.; Ceder, O.

The chronically reserpinized rat has been suggested as an animal model for cystic fibrosis. X-ray microanalysis of thick and thin cryosections was carried out to assess elemental redistribution in the submandibular glands and the pancreas of reserpinized rats at the cellular and subcellular level. In the submandibular gland of reserpinized rats, calcium and magnesium concentrations were significantly elevated. Mucus globules, secretory granules, and endoplasmic reticulum were the primary sites of the localization of excess calcium and magnesium. A significant potassium loss from the gland had occurred, particularly from the serous cells. Electron microscopy of conventionally prepared tissue showed marked swellingmore » of the endoplasmic reticulum, especially in mucous cells. The elemental changes in the pancreatic acinar cells of reserpinized rats were reminiscent of elemental redistribution connected with cell death: increased levels of sodium, chlorine, and calcium and decreased levels of magnesium and potassium. Ultrastructural changes included swelling of the endoplasmic reticulum and obstruction of the acinar lumen. It is concluded tha elemental redistribution in chronically reserpinized rats presents interesting parallels with cystic fibrosis.« less

Preparation of a Ytterbium-tagged Gunshot Residue Standard for Quality Control in the Forensic Analysis of GSR.

PubMed

Hearns, Nigel G R; Laflèche, Denis N; Sandercock, Mark L

2015-05-01

Preparation of a ytterbium-tagged gunshot residue (GSR) reference standard for scanning electron microscopy and energy dispersive X-ray spectroscopic (SEM-EDS) microanalysis is reported. Two different chemical markers, ytterbium and neodymium, were evaluated by spiking the primers of 38 Special ammunition cartridges (no propellant, no projectile) and discharging them onto 12.7 mm diameter aluminum SEM pin stubs. Following SEM-EDS microanalysis, the majority of tri-component particles containing lead, barium, and antimony (PbBaSb) were successfully tagged with the chemical marker. Results demonstrate a primer spiked with 0.75% weight percent of ytterbium nitrate affords PbBaSb particles characteristic of GSR with a ytterbium inclusion efficiency of between 77% and 100%. Reproducibility of the method was verified, and durability of the ytterbium-tagged tri-component particles under repeated SEM-EDS analysis was also tested. The ytterbium-tagged PbBaSb particles impart synthetic traceability to a GSR reference standard and are suitable for analysis alongside case work samples, as a positive control for quality assurance purposes. © 2015 American Academy of Forensic Sciences.

Contamination mitigation strategies for scanning transmission electron microscopy.

PubMed

Mitchell, D R G

2015-06-01

Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Accurate Cross Sections for Microanalysis.

PubMed

Rez, Peter

2002-01-01

To calculate the intensity of x-ray emission in electron beam microanalysis requires a knowledge of the energy distribution of the electrons in the solid, the energy variation of the ionization cross section of the relevant subshell, the fraction of ionizations events producing x rays of interest and the absorption coefficient of the x rays on the path to the detector. The theoretical predictions and experimental data available for ionization cross sections are limited mainly to K shells of a few elements. Results of systematic plane wave Born approximation calculations with exchange for K, L, and M shell ionization cross sections over the range of electron energies used in microanalysis are presented. Comparisons are made with experimental measurement for selected K shells and it is shown that the plane wave theory is not appropriate for overvoltages less than 2.5 V.

Ultrastructural effects on gill tissues induced in red tilapia Oreochromis sp. by a waterborne lead exposure.

PubMed

Aldoghachi, Mohammed A; Azirun, Mohd Sofian; Yusoff, Ismail; Ashraf, Muhammad Aqeel

2016-09-01

Experiments on hybrid red tilapia Oreochromis sp. were conducted to assess histopathological effects induced in gill tissues of 96 h exposure to waterborne lead (5.5 mg/L). These tissues were investigated by light and scanning electron microscopy. Results showed that structural design of gill tissues was noticeably disrupted. Major symptoms were changes of epithelial cells, fusion in adjacent secondary lamellae, hypertrophy and hyperplasia of chloride cells and coagulate necrosis in pavement cells with disappearance of its microridges. Electron microscopic X-ray microanalysis of fish gills exposed to sublethal lead revealed that lead accumulated on the surface of the gill lamella. This study confirmed that lead exposure incited a difference of histological impairment in fish, supporting environmental watch over aquatic systems when polluted by lead.

Hair casts due to a deodorant spray.

PubMed

Ena, Pasquale; Mazzarello, Vittorio; Chiarolini, Fausto

2005-11-01

A 7-year-old girl presented with itching and greyish-white sleeve-like structures in her hair. After ruling out other possible causes for the symptoms, such as nits and dandruff, it was determined that the patient was affected by hair casts. These are small cylindrical structures resembling louse eggs that encircle individual scalp hairs and are easily movable along the hair shafts. It was concluded that she had induced the condition through misuse of a deodorant body spray. Scanning electron microscopy combined with electron dispersive X-ray analysis (X-ray microanalysis) of the hair casts showed the chemical nature of the structures. Some elements present in the composition of the ingredients of the deodorant spray, such as aluminium, chlorine, silicon, magnesium and carbon, were also present in this uncommon type of hair casts.

Australian Red Dune Sand: A Potential Martian Regolith Analog

NASA Technical Reports Server (NTRS)

Kuhlman, K. R.; Marshall, J.; Evans, N. D.; Luttge, A.

2001-01-01

To demonstrate the potential scientific and technical merits of in situ microscopy on Mars, we analyzed a possible Martian regolith analog - an acolian red dune sand from the central Australian desert (near Mt. Olga). This sand was chosen for its ubiquitous red coating and the desert environment in which is it found. Grains of this sand were analyzed using a variety of microanalytical techniques. A database of detailed studies of such terrestrial analogs would assist the study of geological and astrobiological specimens in future missions to Mars. Potential instrument concepts for in situ deployment on Mars include local electrode atom probe nanoanalysis (LEAP), vertical scanning white light interferometry (VSWLI), scanning electron microscopies, energy dispersive x-ray microanalysis (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD). While in situ deployment of these techniques is many years away, ground-based studies using these analytical techniques extend our understanding of the data obtained from instruments to be flown in the near future.

Ionic liquid-templated preparation of mesoporous silica embedded with nanocrystalline sulfated zirconia

PubMed Central

2011-01-01

A series of mesoporous silicas impregnated with nanocrystalline sulphated zirconia was prepared by a sol-gel process using an ionic liquid-templated route. The physicochemical properties of the mesoporous sulphated zirconia materials were studied using characterisation techniques such as inductively coupled optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray microanalysis, elemental analysis and X-ray photoelectron spectroscopy. Analysis of the new silicas indicates isomorphous substitution of silicon with zirconium and reveals the presence of extremely small (< 10 nm) polydispersed zirconia nanoparticles in the materials with zirconium loadings from 27.77 to 41.4 wt.%. PMID:21711725

Filling of single-walled carbon nanotubes by CuI nanocrystals via capillary technique

NASA Astrophysics Data System (ADS)

Chernysheva, M. V.; Eliseev, A. A.; Lukashin, A. V.; Tretyakov, Yu. D.; Savilov, S. V.; Kiselev, N. A.; Zhigalina, O. M.; Kumskov, A. S.; Krestinin, A. V.; Hutchison, J. L.

2007-03-01

The present study is focused on the synthesis and investigation of the nanocomposite CuI@SWNT obtained by the filling of metallic single-walled carbon nanotubes (SWNTs) (inner diameter 1-1.4 nm) by wide-gap semiconducting CuI nanocrystals using so-called capillary technique. The method is based on the impregnation of pre-opened SWNTs by molten CuI in vacuum with subsequent slow cooling to room temperature. SWNTs and CuI@SWNT nanocomposites were studied by nitrogen capillary adsorption method, EDX microanalysis, HRTEM microscopy and Raman spectroscopy. The changing of electronic properties of CuI@SWNT as compare to row nanotubes was observed.

Ultrastructure of selected struvite-containing urinary calculi from cats.

PubMed

Neumann, R D; Ruby, A L; Ling, G V; Schiffman, P S; Johnson, D L

1996-01-01

To elucidate the ultrastructural details of struvite-containing urinary calculi from cats. Specimens studied were inclusive of the range of textures visible during preliminary analysis by use of a stereoscopic dissecting microscope. Textural types, which were used to infer crystal growth conditions, were differentiated with regard to crystal habit, crystal size, growth orientation, and primary porosity. Thirty specimens were selected from a collection of approximately 1,600 feline urinary calculi: 20 of these were composed entirely of struvite, and 10 consisted of struvite and calcium phosphate (apatite). Qualitative and quantitative analyses of specimens included use of plain and polarized light microscopy, x-ray diffractometry, scanning electron microscopy with backscattered electron imagery, x-ray fluorescence scans, and electron probe microanalysis. Four textural types were recognized among struvite calculi, whereas 2 textural types of struvite-apatite calculi were described. The presence of minute, well interconnected primary pores in struvite-containing urinary calculi from cats is an important feature, which may promote possible interaction of calculi with changes in urine composition. Primary porosity, which can facilitate interaction between the calculus and changing urine composition, may explain the efficacy of dietary or medicinal manipulations to promote the dissolution of struvite-containing uroliths from this species.

Morphological changes of olivine grains reacted with amino acid solutions by impact process

NASA Astrophysics Data System (ADS)

Umeda, Yuhei; Takase, Atsushi; Fukunaga, Nao; Sekine, Toshimori; Kobayashi, Takamichi; Furukawa, Yoshihiro; Kakegawa, Takeshi

2017-03-01

Early oceans on Earth might have contained certain amounts of biomolecules such as amino acids, and they were subjected to meteorite impacts, especially during the late heavy bombardment. We performed shock recovery experiments by using a propellant gun in order to simulate shock reactions among olivine as a representative meteorite component, water and biomolecules in oceans in the process of marine meteorite impacts. In the present study, recovered solid samples were analyzed by using X-ray powder diffraction method, scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy with energy-dispersive X-ray spectrometry. The analytical results on shocked products in the recovered sample showed (1) morphological changes of olivine to fiber- and bamboo shoot-like crystals, and to pulverized grains; and features of lumpy surfaces affected by hot water, (2) the formation of carbon-rich substances derived from amino acids, and (3) the incorporation of metals from container into samples. According to the present results, fine-grained olivine in meteorites might have morphologically changed and shock-induced chemical reactions might have been enhanced so that amino acids related to the origin of life may have transformed to carbon-rich substances by impacts.

Analytical Microscopy and Imaging Science | Materials Science | NREL

Science.gov Websites

Microanalysis (EPMA) for quantitative compositional analysis. It relies on wavelength-dispersive spectroscopy to Science group in NREL's Materials Science Center. Mowafak Al-Jassim Group Manager Dr. Al-Jassim manages the Analytical Microscopy and Imaging Science group with the Materials Science Center. Email | 303-384

Possible etiology of calculi formation in salivary glands: biophysical analysis of calculus.

PubMed

Mimura, Masafumi; Tanaka, Nobuyuki; Ichinose, Shizuko; Kimijima, Yutaka; Amagasa, Teruo

2005-09-01

Sialolithiasis is one of the common diseases of the salivary glands. It was speculated that, in the process of calculi formation, degenerative substances are emitted by saliva and calcification then occurs around these substances, and finally calculi are formed. However, the exact mechanism of the formation of calculi is still unclear. In this study, we identify some possible etiologies of calculi formation in salivary glands through biophysical analysis. Calculi from 13 patients with submandibular sialolithiasis were investigated by transmission electron microscopy, scanning electron microscopy, X-ray microanalyzer, and electron diffraction. Transmission electron microscopic observation of calculi was performed in the submandibular gland (n = 13). In 3 of the 13 cases, a number of mitochondria-like structures and lysosomes were found near calcified materials. Scanning electron microscopic examination of these materials revealed that there were lamellar and concentric structures and that the degree of calcification was different among the calculi. X-ray microanalysis disclosed the component elements in the calculi to be Ca, P, S, Na, etc., and the main constituents were Ca and P. The calcium-to-phosphorus ratio was 1.60-1.89. Analysis of the area including mitochondria-like structures, lysosomes, and the fibrous structures by electron diffraction revealed the presence of hydroxyapatite and calcified materials. It is speculated that mitochondria and lysosomal bodies from the ductal system of the submandibular gland are an etiological source for calcification in the salivary gland.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carreras, Alejo C., E-mail: acarreras@famaf.unc.edu.ar; Cangiano, María de los A.; Ojeda, Manuel W.

The influence of the amount of complexing agent added to the starting solution on the physicochemical properties of Cu–Ni nanostructured alloys obtained through a chemical route, was studied. For this purpose, three Cu–Ni nanoalloy samples were synthesized by a previously developed procedure, starting from solutions with citric acid to metal molar ratios (C/Me) of 0.73, 1.00 and 1.50. The synthesis technique consisted in preparing a precursor via the citrate-gel method, and carrying out subsequent thermal treatments in controlled atmospheres. Sample characterization was performed by scanning electron microscopy, X-ray microanalysis, X-ray diffraction, transmission electron microscopy, X-ray nanoanalysis and electron diffraction. Inmore » the three cases, copper and nickel formed a solid solution with a Cu/Ni atomic ratio close to 50/50, and free of impurities inside the crystal structure. The citric acid content of the starting solution proved to have an important influence on the morphology, size distribution, porosity, and crystallinity of the Cu–Ni alloy microparticles obtained, but a lesser influence on their chemical composition. The molar ratio C/Me = 1.00 resulted in the alloy with the Cu/Ni atomic ratio closest to 50/50. - Highlights: • We synthesize Cu–Ni nanoalloys by a chemical route based on the citrate-gel method. • We study the influence of the complexing agent content of the starting solution. • We characterize the samples by electron microscopy and X-ray techniques. • Citric acid influences the shape, size, porosity and crystallinity of the alloys.« less

Microscopy and microanalysis of complex nanosized strengthening precipitates in new generation commercial Al-Cu-Li alloys.

PubMed

Guinel, M J-F; Brodusch, N; Sha, G; Shandiz, M A; Demers, H; Trudeau, M; Ringer, S P; Gauvin, R

2014-09-01

Precipitates (ppts) in new generation aluminum-lithium alloys (AA2099 and AA2199) were characterised using scanning and transmission electron microscopy and atom probe tomography. Results obtained on the following ppts are reported: Guinier-Preston zones, T1 (Al2 CuLi), β' (Al3 Zr) and δ' (Al3 Li). The focus was placed on their composition and the presence of minor elements. X-ray energy-dispersive spectrometry in the electron microscopes and mass spectrometry in the atom probe microscope showed that T1 ppts were enriched in zinc (Zn) and magnesium up to about 1.9 and 3.5 at.%, respectively. A concentration of 2.5 at.% Zn in the δ' ppts was also measured. Unlike Li and copper, Zn in the T1 ppts could not be detected using electron energy-loss spectroscopy in the transmission electron microscope because of its too low concentration and the small sizes of these ppts. Indeed, Monte Carlo simulations of EEL spectra for the Zn L2,3 edge showed that the signal-to-noise ratio was not high enough and that the detection limit was at least 2.5 at.%, depending on the probe current. Also, the simulation of X-ray spectra confirmed that the detection limit was exceeded for the Zn Kα X-ray line because the signal-to-noise ratio was high enough in that case, which is in agreement with our observations. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

In vitro corrosion resistance of plasma source ion nitrided austenitic stainless steels.

PubMed

Le, M K; Zhu, X M

2001-04-01

Plasma source ion nitriding has emerged as a low-temperature, low-pressure nitriding approach for low-energy implanting nitrogen ions and then diffusing them into steel and alloy. In this work, a single high nitrogen face-centered-cubic (f.c.c.) phase (gammaN) formed on the 1Cr18Ni9Ti and AISI 316L austenitic stainless steels with a high nitrogen concentration of about 32 at % was characterized using Auger electron spectroscopy, electron probe microanalysis, glancing angle X-ray diffraction, and transmission electron microscopy. The corrosion resistance of the gammaN-phase layer was studied by the electrochemical cyclic polarization measurement in Ringer's solutions buffered to pH from 3.5 to 7.2 at a temperature of 37 degrees C. No pitting corrosion in the Ringer's solutions with pH = 7.2 and 5.5 was detected for the gammaN-phase layers on the two stainless steels. The high pitting potential for the gammaN-phase layers is higher, about 500 and 600 mV, above that of the two original stainless steels, respectively, in the Ringer's solution with pH = 3.5. The corroded surface morphologies of the gammaN-phase layers observed by scanning electron microscopy are consistent with the results of the electrochemical polarization measurement.

Measurement of Total Calcium in Neurons by Electron Probe X-ray Microanalysis

PubMed Central

Pivovarova, Natalia B.; Andrews, S. Brian

2013-01-01

In this article the tools, techniques, and instruments appropriate for quantitative measurements of intracellular elemental content using the technique known as electron probe microanalysis (EPMA) are described. Intramitochondrial calcium is a particular focus because of the critical role that mitochondrial calcium overload plays in neurodegenerative diseases. The method is based on the analysis of X-rays generated in an electron microscope (EM) by interaction of an electron beam with the specimen. In order to maintain the native distribution of diffusible elements in electron microscopy specimens, EPMA requires "cryofixation" of tissue followed by the preparation of ultrathin cryosections. Rapid freezing of cultured cells or organotypic slice cultures is carried out by plunge freezing in liquid ethane or by slam freezing against a cold metal block, respectively. Cryosections nominally 80 nm thick are cut dry with a diamond knife at ca. -160 °C, mounted on carbon/pioloform-coated copper grids, and cryotransferred into a cryo-EM using a specialized cryospecimen holder. After visual survey and location mapping at ≤-160 °C and low electron dose, frozen-hydrated cryosections are freeze-dried at -100 °C for ~30 min. Organelle-level images of dried cryosections are recorded, also at low dose, by means of a slow-scan CCD camera and subcellular regions of interest selected for analysis. X-rays emitted from ROIs by a stationary, focused, high-intensity electron probe are collected by an energy-dispersive X-ray (EDX) spectrometer, processed by associated electronics, and presented as an X-ray spectrum, that is, a plot of X-ray intensity vs. energy. Additional software facilitates: 1) identification of elemental components by their "characteristic" peak energies and fingerprint; and 2) quantitative analysis by extraction of peak areas/background. This paper concludes with two examples that illustrate typical EPMA applications, one in which mitochondrial calcium analysis provided critical insight into mechanisms of excitotoxic injury and another that revealed the basis of ischemia resistance. PMID:24300079

Scanning Electron Microscopy and X-Ray Microanalysis for Chemical and Morphological Characterisation of the Inorganic Component of Gunshot Residue: Selected Problems

PubMed Central

Brożek-Mucha, Zuzanna

2014-01-01

Chosen aspects of examinations of inorganic gunshot particles by means of scanning electron microscopy and energy dispersive X-ray spectrometry technique are presented. The research methodology of particles was worked out, which included a precise and repeatable procedure of the automatic detection and identification of particles as well as the representation of the obtained analytical data in the form of the frequencies of occurrence of particles of certain chemical or morphological class within the whole population of particles revealed in a specimen. On this basis, there were established relationships between the chemical and morphological properties of populations of particles and factors, such as the type of ammunition, the distance from the gun muzzle to the target, the type of a substrate the particles sediment on, and the time between shooting and collecting the specimens. Each of these aspects of examinations of particles revealed a great potential of being utilised in casework, while establishing various circumstances of shooting incidents leads to the reconstruction of the course of the studied incident. PMID:25025050

Bricks in historical buildings of Toledo City: characterisation and restoration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez-Arce, Paula; Garcia-Guinea, Javier; Gracia, Mercedes

2003-01-15

Two different types of ancient bricks (12th to 14th centuries) collected from historical buildings of Toledo (Spain) were characterised by optical microscopy, scanning electron microscopy/energy-dispersive X-ray spectrometers (SEM/EDS), electron probe microanalysis (EM), X-ray diffraction (XRD), differential thermal analysis (DTA) and {sup 57}Fe-Moessbauer spectroscopy. Physical properties such as water absorption and suction, porosity, density and compression strength were also determined. Several minerals found in the brick matrix, such as garnet, let us infer raw material sources; calcite, dolomite, illite and neoformed gehlenite and diopside phases, on temperature reached in firing; secondary calcite, on first cooling scenarios; and manganese micronodules, on latemore » pollution environments. XRD and DTA of original and refired samples supply information about firing temperatures. Additional data on firing conditions and type of the original clay are provided by the Moessbauer study. Physical properties of both types of bricks were compared and correlated with raw materials and fabric and firing technology employed. The physicochemical characterisation of these bricks provides valuable data for restoration purposes to formulate new specific bricks using neighbouring raw materials.« less

Advanced microscopy of star-shaped gold nanoparticles and their adsorption-uptake by macrophages

PubMed Central

Plascencia-Villa, Germán; Bahena, Daniel; Rodríguez, Annette R.; Ponce, Arturo; José-Yacamán, Miguel

2013-01-01

Metallic nanoparticles have diverse applications in biomedicine, as diagnostics, image contrast agents, nanosensors and drug delivery systems. Anisotropic metallic nanoparticles possess potential applications in cell imaging and therapy+diagnostics (theranostics), but controlled synthesis and growth of these anisotropic or branched nanostructures has been challenging and usually require use of high concentrations of surfactants. Star-shaped gold nanoparticles were synthesized in high yield through a seed mediated route using HEPES as a precise shape-directing capping agent. Characterization was performed using advanced electron microscopy techniques including atomic resolution TEM, obtaining a detailed characterization of nanostructure and atomic arrangement. Spectroscopy techniques showed that particles have narrow size distribution, monodispersity and high colloidal stability, with absorbance into NIR region and high efficiency for SERS applications. Gold nanostars showed to be biocompatible and efficiently adsorbed and internalized by macrophages, as revealed by advanced FE-SEM and backscattered electron imaging techniques of complete unstained uncoated cells. Additionally, low voltage STEM and X-ray microanalysis revealed the ultra-structural location and confirmed stability of nanoparticles after endocytosis with high spatial resolution. PMID:23443314

Distribution of trace elements in a modified and grain refined aluminium-silicon hypoeutectic alloy.

PubMed

Faraji, M; Katgerman, L

2010-08-01

The influence of modifier and grain refiner on the nucleation process of a commercial hypoeutectic Al-Si foundry alloy (A356) was investigated using optical microscopy, scanning electron microscopy (SEM) and electron probe microanalysis technique (EPMA). Filtering was used to improve the casting quality; however, it compromised the modification of silicon. Effect of filtering on strontium loss was also studied using the afore-mentioned techniques. EPMA was used to trace the modifying and grain refining agents inside matrix and eutectic Si. This was to help understanding mechanisms of nucleation and modification in this alloy. Using EPMA, the negative interaction of Sr and Al3TiB was closely examined. In modified structure, it was found that the maximum point of Sr concentration was in line with peak of silicon; however, in case of just 0.1wt% added Ti, the peak of Ti concentration was not in line with aluminium, (but it was close to Si peak). Furthermore, EPMA results showed that using filter during casting process lowered the strontium content, although produced a cleaner melt. (c) 2010 Elsevier Ltd. All rights reserved.

Influence of substrate material and surface finishing on the morphology of the calcium-phosphate coating.

PubMed

Leitão, E; Barbosa, M A; de Groot, K

1997-07-01

The formation of an apatite-like layer was achieved by immersing Ti-6A1-4V, Ti-Al-2.5Fe, and 316 L stainless-steel substrata in Hank's balanced salt solution (HBSS). The layer was characterized by surface analysis techniques, namely X-ray microanalysis and X-ray diffraction, and the morphology was observed by scanning electron microscopy and atomic force microscopy. The concentrations of Ca and P were monitored as a function of time. The morphology of the precipitate layer seems to be dependent both on the type of metal substrate and its surface finish. Polished Ti-6A1-4V and Ti-Al-2.5Fe surfaces exhibit a plate precipitate morphology, whereas rougher surfaces show scattered crystal-like precipitation. The results suggest that the layer produced by immersion of polished titanium alloys in HBSS is constituted by an amorphous apatite.

Microscopy and Microanalysis of Blood in a Snake Head Fish, Channa gachua Exposed to Environmental Pollution.

PubMed

Pala, Eva M; Dey, Sudip

2016-02-01

Conventional and highly sophisticated analytical methods (Cyria et al., 1989; Massar et al., 2012a) were used to analyze micro-structural and micro-analytical aspects of the blood of snake head fish, Channa gachua, exposed to municipal wastes and city garbage. Red (RBC) and white blood cell (WBC) counts and hemhemoglobin content were found to be higher in pollution affected fish as compared with control. Scanning electron microscopy revealed the occurrence of abnormal erythrocytes such as crenated cells, echinocytes, lobopodial projections, membrane internalization, spherocytes, ruptured cells, contracted cells, depression, and uneven elongation of erythrocyte membranes in fish inhabiting the polluted sites. Energy-dispersive X-ray spectroscopy (EDS) revealed the presence of silicon and lead in the RBCs of pollution affected fish. Significance of the study includes the highly sophisticated analytical approach, which revealed the aforementioned micro-structural abnormalities.

Effect of different atmospheres on the electrical contact performance of electronic components under fretting wear

NASA Astrophysics Data System (ADS)

Liu, Xin-Long; Cai, Zhen-Bing; Cui, Ye; Liu, Shan-Bang; Xu, Xiao-Jun; Zhu, Min-Hao

2018-04-01

The effects of oxide etch on the surface morphology of metals for industrial application is a common cause of electrical contacts failure, and it has becomes a more severe problem with the miniaturization of modern electronic devices. This study investigated the effects of electrical contact resistance on the contactor under three different atmospheres (oxygen, air, and nitrogen) based on 99.9% copper/pogo pins contacts through fretting experiments. The results showed the minimum and stable electrical contact resistance value when shrouded in the nitrogen environment and with high friction coefficient. The rich oxygen environment promotes the formation of cuprous oxide, thereby the electrical contact resistance increases. Scanning electron microscope microscopy and electron probe microanalysis were used to analyze the morphology and distribution of elements of the wear area, respectively. The surface product between contacts was investigated by x-ray photoelectron spectroscopy analysis to explain the different electrical contact properties of the three tested samples during fretting.

Improved oxidation resistance of organic/inorganic composite atomic layer deposition coated cellulose nanocrystal aerogels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Sean W.; Matthews, David J.; Conley, John F., E-mail: jconley@eecs.oregonstate.edu

2014-07-01

Cellulose nanocrystal (CNC) aerogels are coated with thin conformal layers of Al{sub 2}O{sub 3} using atomic layer deposition to form hybrid organic/inorganic nanocomposites. Electron probe microanalysis and scanning electron microscopy analysis indicated the Al{sub 2}O{sub 3} penetrated more than 1500 μm into the aerogel for extended precursor pulse and exposure/purge times. The measured profile of coated fiber radius versus depth from the aerogel surface agrees well with simulations of precursor penetration depth in modeled aerogel structures. Thermogravimetric analysis shows that Al{sub 2}O{sub 3} coated CNC aerogel nanocomposites do not show significant thermal degradation below 295 °C as compared with 175 °C for uncoatedmore » CNC aerogels, an improvement of over 100 °C.« less

Effect of polymer matrix on structure of Se particles formed in aqueous solutions during redox process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suvorova, E. I., E-mail: suvorova@ns.crys.ras.ru; Klechkovskaya, V. V.

2010-12-15

Transmission electron microscopy and X-ray energy dispersive microanalysis study of the structure of particles formed during the reduction of Se(IV) to Se(0) in aqueous solutions in the presence of amphiphilic polymers showed the formation of Se/polymer composite particles. The content of carbon inside the particles can be as large as 80 at %. Polymers deeply influence the structure of particles. Depending on polymers, the composite particles may be unstable with time and they spontaneously evolve from Se/polymer composite particles to crystalline particles of monoclinic Se. For the stable ones, addition of bacterial cellulose Acetobacter xylinum gel-film can induce crystallization inmore » the particles which expel the polymeric material. The Se/polymer composite particles and Se crystalline particles exhibit different sensitivity to electron irradiation and stiffness.« less

Hybrid magnetic materials formed by ferritin intercalated into a layered double hydroxide

NASA Astrophysics Data System (ADS)

Clemente-León, Miguel; Coronado, Eugenio; Primo, Vicent; Ribera, Antonio; Soriano-Portillo, Alejandra

2008-12-01

A hybrid magnetic material formed by ferritin intercalated into a layered double hydroxide (LDH) of Mg and Al (Mg/Al molar ratio 2) is prepared and characterized through powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) spectroscopy, electron probe microanalysis (EPMA) and high resolution transmission electron microscopy (HRTEM). One observes an enhancement in the thermal stability of the ferritin molecules when they are inserted in the layered material. Magnetic measurements of the hybrid material exhibit the typical superparamagnetic behaviour of the ferritin molecule. On the other hand, the intercalation of ferritin into the LDH guarantees a homogeneous dispersion of the ferritin molecules, which do not aggregate even after calcination of the sample. This feature allows obtaining well-dispersed magnetic metal oxide nanoparticles upon calcination of the hybrid material.

Hydroxyapatite coatings produced on commercially pure titanium by micro-arc oxidation.

PubMed

Huang, Yong; Wang, Yingjun; Ning, Chengyun; Nan, Kaihui; Han, Yong

2007-09-01

A porous hydroxyapatite (HA) coating on commercially pure titanium was prepared by micro-arc oxidation (MAO) in electrolytic solution containing calcium acetate and beta-glycerol phosphate disodium salt pentahydrate (beta-GP). The thickness, phase, composition morphology and biocompatibility of the oxide coating were characterized by x-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM) with an energy dispersive x-ray spectrometer (EDS) and cell culture. The thickness of the MAO film was about 20 microm, and the coating was porous and uneven without any apparent interface to the titanium substrates. The result of XRD showed that the porous coating was made up of HA film. The favorable osteoblast cell affinity gives HA film good biocompatibility. HA coatings are expected to have significant uses for medical applications such as dental implants and artificial bone joints.

Microstructures of ancient and modern cast silver–copper alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Northover, S.M., E-mail: s.m.northover@open.ac.uk; Northover, J.P., E-mail: peter.northover@materials.ox.ac.uk

The microstructures of modern cast Sterling silver and of cast silver objects about 2500 years old have been compared using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray microanalysis (EDX) and electron backscatter diffraction (EBSD). Microstructures of both ancient and modern alloys were typified by silver-rich dendrites with a few pools of eutectic and occasional cuprite particles with an oxidised rim on the outer surface. EBSD showed the dendrites to have a complex internal structure, often involving extensive twinning. There was copious intragranular precipitation within the dendrites, in themore » form of very fine copper-rich rods which TEM, X-ray diffraction (XRD), SEM and STEM suggest to be of a metastable face-centred-cubic (FCC) phase with a cube–cube orientation relationship to the silver-rich matrix but a higher silver content than the copper-rich β in the eutectic. Samples from ancient objects displayed a wider range of microstructures including a fine scale interpenetration of the adjoining grains not seen in the modern material. Although this study found no unambiguous evidence that this resulted from microstructural change produced over archaeological time, the copper supersaturation remaining after intragranular precipitation suggests that such changes, previously proposed for wrought and annealed material, may indeed occur in ancient silver castings. - Highlights: • Similar twinned structures and oxidised surfaces seen in ancient and modern cast silver • General precipitation of fine Cu-rich rods apparently formed by discontinuous precipitation is characteristic of as-cast silver. • The fine rods are cube-cube related to the matrix in contrast with the eutectic. • The silver-rich phase remains supersaturated with copper. • Possibly age-related grain boundary features seen in ancient cast silver.« less

A multimodal microcharacterisation of trace-element zonation and crystallographic orientation in natural cassiterite by combining cathodoluminescence, EBSD, EPMA and contribution of confocal Raman-in-SEM imaging.

PubMed

Wille, G; Lerouge, C; Schmidt, U

2018-01-16

In cassiterite, tin is associated with metals (titanium, niobium, tantalum, indium, tungsten, iron, manganese, mercury). Knowledge of mineral chemistry and trace-element distribution is essential for: the understanding of ore formation, the exploration phase, the feasibility of ore treatment, and disposal/treatment of tailings after the exploitation phase. However, the availability of analytical methods make these characterisations difficult. We present a multitechnical approach to chemical and structural data that includes scanning electron microscopy (SEM)-based imaging and microanalysis techniques such as: secondary and backscattered electrons, cathodoluminescence (CL), electron probe microanalyser (EPMA), electron backscattered diffraction (EBSD) and confocal Raman-imaging integrated in a SEM (RISE). The presented results show the complementarity of the used analytical techniques. SEM, CL, EBSD, EPMA provide information from the interaction of an electron beam with minerals, leading to atomistic information about their composition, whereas RISE, Raman spectroscopy and imaging completes the studies with information about molecular vibrations, which are sensitive to structural modifications of the minerals. The correlation of Raman bands with the presence/absence of Nb, Ta, Fe (heterovalent substitution) and Ti (homovalent substitution) is established at a submicrometric scale. Combination of the different techniques makes it possible to establish a direct link between chemical and crystallographic data of cassiterite. © 2018 The Authors Journal of Microscopy © 2018 Royal Microscopical Society.

Scanning probe microscopy in mineralogical studies: about origin of the observed roughness of natural silica-rich glasses

NASA Astrophysics Data System (ADS)

Golubev, Ye A.; Isaenko, S. I.

2017-10-01

We have studied different mineralogical objects: natural glasses of impact (tektites, impactites) and volcanic (obsidians) origin, using atomic force microscopy, X-ray microanalysis, infrared and Raman spectroscopy. The spectroscopy showed the difference in the structure and chemical composition of the glasses of different origin. The analysis of the dependence of nanoscale heterogeneity of the glasses, revealed by the atomic force microscopy, on their structural and chemical features was carried out.

Emerging surface characterization techniques for carbon steel corrosion: a critical brief review.

PubMed

Dwivedi, D; Lepkova, K; Becker, T

2017-03-01

Carbon steel is a preferred construction material in many industrial and domestic applications, including oil and gas pipelines, where corrosion mitigation using film-forming corrosion inhibitor formulations is a widely accepted method. This review identifies surface analytical techniques that are considered suitable for analysis of thin films at metallic substrates, but are yet to be applied to analysis of carbon steel surfaces in corrosive media or treated with corrosion inhibitors. The reviewed methods include time of flight-secondary ion mass spectrometry, X-ray absorption spectroscopy methods, particle-induced X-ray emission, Rutherford backscatter spectroscopy, Auger electron spectroscopy, electron probe microanalysis, near-edge X-ray absorption fine structure spectroscopy, X-ray photoemission electron microscopy, low-energy electron diffraction, small-angle neutron scattering and neutron reflectometry, and conversion electron Moessbauer spectrometry. Advantages and limitations of the analytical methods in thin-film surface investigations are discussed. Technical parameters of nominated analytical methods are provided to assist in the selection of suitable methods for analysis of metallic substrates deposited with surface films. The challenges associated with the applications of the emerging analytical methods in corrosion science are also addressed.

Emerging surface characterization techniques for carbon steel corrosion: a critical brief review

NASA Astrophysics Data System (ADS)

Dwivedi, D.; Lepkova, K.; Becker, T.

2017-03-01

Carbon steel is a preferred construction material in many industrial and domestic applications, including oil and gas pipelines, where corrosion mitigation using film-forming corrosion inhibitor formulations is a widely accepted method. This review identifies surface analytical techniques that are considered suitable for analysis of thin films at metallic substrates, but are yet to be applied to analysis of carbon steel surfaces in corrosive media or treated with corrosion inhibitors. The reviewed methods include time of flight-secondary ion mass spectrometry, X-ray absorption spectroscopy methods, particle-induced X-ray emission, Rutherford backscatter spectroscopy, Auger electron spectroscopy, electron probe microanalysis, near-edge X-ray absorption fine structure spectroscopy, X-ray photoemission electron microscopy, low-energy electron diffraction, small-angle neutron scattering and neutron reflectometry, and conversion electron Moessbauer spectrometry. Advantages and limitations of the analytical methods in thin-film surface investigations are discussed. Technical parameters of nominated analytical methods are provided to assist in the selection of suitable methods for analysis of metallic substrates deposited with surface films. The challenges associated with the applications of the emerging analytical methods in corrosion science are also addressed.

Emerging surface characterization techniques for carbon steel corrosion: a critical brief review

PubMed Central

Dwivedi, D.; Becker, T.

2017-01-01

Carbon steel is a preferred construction material in many industrial and domestic applications, including oil and gas pipelines, where corrosion mitigation using film-forming corrosion inhibitor formulations is a widely accepted method. This review identifies surface analytical techniques that are considered suitable for analysis of thin films at metallic substrates, but are yet to be applied to analysis of carbon steel surfaces in corrosive media or treated with corrosion inhibitors. The reviewed methods include time of flight-secondary ion mass spectrometry, X-ray absorption spectroscopy methods, particle-induced X-ray emission, Rutherford backscatter spectroscopy, Auger electron spectroscopy, electron probe microanalysis, near-edge X-ray absorption fine structure spectroscopy, X-ray photoemission electron microscopy, low-energy electron diffraction, small-angle neutron scattering and neutron reflectometry, and conversion electron Moessbauer spectrometry. Advantages and limitations of the analytical methods in thin-film surface investigations are discussed. Technical parameters of nominated analytical methods are provided to assist in the selection of suitable methods for analysis of metallic substrates deposited with surface films. The challenges associated with the applications of the emerging analytical methods in corrosion science are also addressed. PMID:28413351

Effect of Homogenization on Microstructure Characteristics, Corrosion and Biocompatibility of Mg-Zn-Mn-xCa Alloys

PubMed Central

Li, Jingyuan; Lai, Huiying; Xu, Yuzhao

2018-01-01

The corrosion behaviors of Mg-2Zn-0.2Mn-xCa (denoted as MZM-xCa alloys) in homogenization state have been investigated by immersion test and electrochemical techniques in a simulated physiological condition. The microstructure features were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), and the corrosion mechanism was illustrated using atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and confocal laser scanning microscopy (CLSM). The electrochemical and immersion test verify the MZM-0.38% Ca owns the best corrosion performance with the corrosion rate of 6.27 mm/year. Furthermore, the film layer of MZM-0.38% Ca is more compact and denser than that of others. This improvement could be associated with the combined effects of the suitable content of Zn/Ca dissolving into the α-Mg matrix and the modification of Ca-containing compounds by heat-treatment. However, the morphologies were transformed from uniform corrosion to localized pitting corrosion with Ca further addition. It could be explained that the excessive Ca addition can strengthen the nucleation driving force for the second phase formation, and the large volumes fraction of micro-galvanic present interface sites accelerate the nucleation driving force for corrosion propagation. In addition, in vitro biocompatibility tests also show the MZM-0.38% Ca was safe to bone mesenchymal stem cells (BMSCs) and was promising to be utilized as implant materials. PMID:29389894

Synthesis of Al₂Ca Dispersoids by Powder Metallurgy Using a Mg-Al Alloy and CaO Particles.

PubMed

Fujita, Junji; Umeda, Junko; Kondoh, Katsuyoshi

2017-06-28

The elemental mixture of Mg-6 wt %Al-1 wt %Zn-0.3 wt %Mn (AZ61B) alloy powder and CaO particles was consolidated by an equal-channel angular bulk mechanical alloying (ECABMA) process to form a composite precursor. Subsequently, the precursor was subjected to a heat treatment to synthesize fine Al₂Ca particles via a solid-state reaction between the Mg-Al matrix and CaO additives. Scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) and electron probe micro-analysis on the precursor indicated that 4.7-at % Al atoms formed a supersaturated solid solution in the α-Mg matrix. Transmission electron microscopy-EDS and X-ray diffraction analyses on the AZ61B composite precursor with 10-vol % CaO particles obtained by heat treatment confirmed that CaO additives were thermally decomposed in the Mg-Al alloy, and the solid-soluted Ca atoms diffused along the α-Mg grain boundaries. Al atoms also diffused to the grain boundaries because of attraction to the Ca atoms resulting from a strong reactivity between Al and Ca. As a result, needle-like (Mg,Al)₂Ca intermetallics were formed as intermediate precipitates in the initial reaction stage during the heat treatment. Finally, the precipitates were transformed into spherical Al₂Ca particles by the substitution of Al atoms for Mg atoms in (Mg,Al)₂Ca after a long heat treatment.

Evaluation of the infection process by Lecanicillium fungicola in Agaricus bisporus by scanning electron microscopy.

PubMed

Santana Nunes, Janaira; Rocha de Brito, Manuela; Cunha Zied, Diego; Aparecida das Graças Leite, Eloisa; Souza Dias, Eustáquio; Alves, Eduardo

Lecanicillium fungicola causes dry bubble disease in Agaricus bisporus mushrooms leading to significant economic losses in commercial production. To monitor the infection process of L. fungicola in Brazilian strains of A. bisporus. The interaction between the mycelium of L. fungicola (LF.1) and three strains of A. bisporus (ABI 7, ABI 11/14 and ABI 11/21) was studied. Electron microscopy and X-ray microanalyses of vegetative growth and basidiocarp infection were evaluated. Micrographs show that the vegetative mycelium of the Brazilian strains of A. bisporus is not infected by the parasite. The images show that the pathogen can interlace the hyphae of A. bisporus without causing damage, which contributes to the presence of L. fungicola during the substrate colonization, allowing their presence during primordial formation of A. bisporus. In the basidiocarp, germ tubes form within 16h of infection with L. fungicola and the beginning of penetration takes place within 18h, both without the formation of specialized structures. Scanning electron microscopy enabled the process of colonization and reproduction to be observed within the formation of phialides, conidiophores and verticils of L. fungicola. The formation of calcium oxalate crystals by the pathogen was also visible using the X-ray microanalysis, both at the hyphae in the Petri plate and at basidiocarp infection site. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

Ultrastructure, Histochemistry, and Mineralization Patterns in the Ecdysial Suture of the Blue Crab, Callinectes sapidus

NASA Astrophysics Data System (ADS)

Priester, Carolina; Dillaman, Richard M.; Gay, D. Mark

2005-12-01

The ecdysial suture is the region of the arthropod exoskeleton that splits to allow the animal to emerge during ecdysis. We examined the morphology and composition of the intermolt and premolt suture of the blue crab using light microscopy and scanning electron microscopy. The suture could not be identified by routine histological techniques; however 3 of 22 fluorescein isothiocyanate-labeled lectins tested (Lens culinaris agglutinin, Vicia faba agglutinin, and Pisum sativum agglutinin) differentiated the suture, binding more intensely to the suture exocuticle and less intensely to the suture endocuticle. Back-scattered electron (BSE) and secondary electron observations of fracture surfaces of intermolt cuticle showed less mineralized regions in the wedge-shaped suture as did BSE analysis of premolt and intermolt resin-embedded cuticle. The prism regions of the suture exocuticle were not calcified. X-ray microanalysis of both the endocuticle and exocuticle demonstrated that the suture was less calcified than the surrounding cuticle with significantly lower magnesium and phosphorus concentrations, potentially making its mineral more soluble. The presence or absence of a glycoprotein in the organic matrix, the extent and composition of the mineral deposited, and the thickness of the cuticle all likely contribute to the suture being removed by molting fluid, thereby ensuring successful ecdysis.

Alkali-aggregate reaction under the influence of deicing salts in the Hokuriku district, Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katayama, Tetsuya; Tagami, Masahiko; Sarai, Yoshinori

2004-11-15

Concrete cores taken from highway bridges and culverts undergoing alkali-silica reaction (ASR) were investigated petrographically by means of core scanning, point counting, polarizing microscopy, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), electron-probe microanalysis with energy-dispersive spectrometry, in conjunction with wet chemical analyses and expansion tests. Field damage was roughly proportional to the content of andesite in the gravel aggregates due to the presence of highly reactive cristobalite and tridymite. Electron-probe microanalyzer analysis of unhydrated cement phases in the concrete revealed that the cement used had contained at least 0.5% to 1.0% alkali (Na{sub 2}Oeq) and that both the aggregatesmore » and the deicing salts had supplied part of the water-soluble alkali to concrete toward the threshold of producing ASR (Na{sub 2}O{sub eq} 3.0 kg/m{sup 3}). An accelerated concrete core expansion test (1 M NaOH, 80 deg. C) of the damaged structures mostly gave core expansions of >0.10% at 21 days (or >0.05% at 14 days), nearly comparable to those of a slow expansion test with saturated NaCl solution (50 deg. C, 91 days) which produced Cl-containing ASR gel.« less

Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osoba, L.O.; Ding, R.G.; Ojo, O.A., E-mail: ojo@cc.umanitoba.ca

Analytical electron microscopy and spectroscopy analyses of the fusion zone (FZ) microstructure in autogenous laser beam welded Haynes 282 (HY 282) superalloy were performed. The micro-segregation patterns observed in the FZ indicate that Co, Cr and Al exhibited a nearly uniform distribution between the dendrite core and interdendritic regions while Ti and Mo were rejected into the interdendritic liquid during the weld solidification. Transmission electron diffraction analysis and energy dispersive X-ray microanalysis revealed the second phase particles formed along the FZ interdendritic region to be Ti-Mo rich MC-type carbide particles. Weld FZ solidification cracking, which is sometimes associated with themore » formation of {gamma}-{gamma}' eutectic in {gamma}' precipitation strengthened nickel-base superalloys, was not observed in the HY 282 superalloy. Modified primary solidification path due to carbon addition in the newly developed superalloy is used to explain preclusion of weld FZ solidification cracking in the material. - Highlights: Black-Right-Pointing-Pointer A newly developed superalloy was welded by CO{sub 2} laser beam joining technique. Black-Right-Pointing-Pointer Electron microscopy characterization of the weld microstructure was performed. Black-Right-Pointing-Pointer Identified interdendritic microconstituents consist of MC-type carbides. Black-Right-Pointing-Pointer Modification of primary solidification path is used to explain cracking resistance.« less

The lack of age-pigments and the alterations in intracellular monovalent electrolytes in spontaneously hypertensive, stroke-prone (SHRsp) rats as revealed by electron microscopy and X-ray microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zs.-Nagy, I.; Zs.-Nagy, V.; Casoli, T.

1989-01-01

Male, spontaneously hypertensive, stroke-prone (SHRsp) rats established by Okamoto et al. were studied. About 80% of the males of this strain have a particularly short life span (33-41 weeks); they display a considerable hypertension (above 220 mmHg) and a tendency for plurifocal brain strokes. Hypertension and strokes can be provoked in an accelerated and synchronized fashion by supplementing 1% NaCl into their drinking water. Symptoms of the appearance of brain strokes can be judged from characteristic signs of motor disorders, and can be established also by pathohistology. Since hypertension and arteriosclerosis are frequently involved in aging, the question we intendedmore » to answer was whether these animals may represent a model of the normal aging process or not. Two approaches are described: (1) Accumulation of lipofuscin granules in their brain, liver and myocardium was followed by transmission electron microscopy before and after the appearance of strokes. It has been established that these tissues do not show any typical accumulation of lipofuscin granules, although submicroscopic signs of an enhanced damage of cell organelles (especially of mitochondria in liver and brain cells, but not in myocardium) were encountered. (2) The intracellular monovalent composition in the brain and liver was measured by using bulk-specimen X-ray microanalysis. The intracellular Na-content (mEq/kg water) was significantly higher (170-200%) in both the brain and liver cells, whereas the K-content increased only moderately (118-130%). The results suggest that although the SHRsp rats do not represent a direct model for the normal aging process from the point of view of lipofuscin accumulation, the shifts of the monovalent electrolyte contents in the brain and liver cells observed already in the youngest ages, are similar to those observed in aged normal rats.« less

Electron Microscope Studies of Cadmium Mercury Telluride

NASA Astrophysics Data System (ADS)

Lyster, Martin

Available from UMI in association with The British Library. Requires signed TDF. Epitaxial layers of Cd_{x }Hg_{(1-x)}Te grown on various substrates by liquid phase epitaxy and metallo-organic vapour phase epitaxy have been studied using transmission and scanning electron microscopy, in a variety of contrast modes. Wavelength-dispersive X-ray microanalysis has been used to study interfaces in epitaxial specimens, and the results are used to derive diffusion coefficients for a range of values of x in Cd_ {x}Hg_{(1-x)} Te. Extensive use has been made of back-scattered electron contrast in the SEM as a means of compositional mapping, and defect structures are imaged by this technique. The back-scattered electron contrast at interfaces has been studied in detail and is modelled using the Monte Carlo approach. The modelling is combined with calculations and practical measurements of the probe size in the SEM instrument used in the work, to arrive at a quantitative explanation of this contrast. The SEM and scintillator detector used allow a spatial resolution of better than 1000A, but it is shown that improvements in this are possible with present technology. Scanning infra-red microscopy (SIRM) and high -resolution transmission electron microscopy (HREM) have been applied to the study of CdTe. SIRM images reveal information about Te precipitation, including particle size and density. HREM images provide results concerning dislocation structures in CdTe. Selected-area diffraction contrast TEM results are presented which illustrate the microstructure of LPE and MOVPE material; and TEM foil preparation techniques are discussed, including the choice of ion species for milling cross-sectional specimens. In view of the results obtained, suggestions are made for future work in this field.

Effects of In and Ni Addition on Microstructure of Sn-58Bi Solder Joint

NASA Astrophysics Data System (ADS)

Mokhtari, Omid; Nishikawa, Hiroshi

2014-11-01

In this study, the effect of adding 0.5 wt.% and 1 wt.% In and Ni to Sn-58Bi solder on intermetallic compound (IMC) layers at the interface and the microstructure of the solder alloys were investigated during reflow and thermal aging by scanning electron microscopy and electron probe micro-analysis. The results showed that the addition of minor elements was not effective in suppressing the IMC growth during the reflow; however, the addition of 0.5 wt.% In and Ni was effective in suppressing the IMC layer growth during thermal aging. The thickening kinetics of the total IMC layer was analyzed by plotting the mean thickness versus the aging time on log-log coordinates, and the results showed the transition point from grain boundary diffusion control to a volume diffusion control mechanism. The results also showed that the minor addition of In can significantly suppress the coarsening of the Bi phase.

Gibbsite Growth History — Revelations of a New Scanning Electron Microscope Technique

NASA Astrophysics Data System (ADS)

Roach, Gerald I. D.; Cornell, John B.; Griffin, Brendan J.

A new scanning electron microscope technique termed charge contrast imaging (CCI), unique to the Environmental SEM, has been developed at the Centre for Microscopy and Microanalysis. The technique enables the growth history of gibbsite particles from the Bayer process to be studied. The technique is used on uncoated polished sections. The seed gibbsite is clearly distinguished from freshly precipitated gibbsite enabling information on agglomeration and growth to be unambiguously obtained. Growth rings associated with each pass through precipitation are readily observed which enables the complete growth history of a particle to be ascertained; for example batch and continuously grown gibbsites can be distinguished. Growth of gibbsite on different crystal faces can be directly measured and the presence of secondary nucleation detected. The data obtained via this technique have been confirmed using specially prepared laboratory samples. The technique is now finding wider application in areas such as medicine (examination of kidney stones), mineralogy and ceramics.

The osteoplastic effectiveness of the implants made of mesh titanium nickelide constructs.

PubMed

Mikhailovich Irianov, Iurii; Vladimirovna Diuriagina, Olga; Iurevna Karaseva, Tatiana; Anatolevich Karasev, Evgenii

2014-02-01

The purpose of the work was to study the features of reparative osteogenesis for filling the defect of tubular bone under implantation of mesh titanium nickelide constructs. Tibial fenestrated defect was modeled experimentally in 30 Wistar pubertal rats, followed by implant intramedullary insertion. The techniques of radiography, scanning electron microscopy and X-ray electron probe microanalysis were used. The mesh implant of titanium nickelide has been established to possess biocompatibility, osteoconductive and osteoinductive properties, the zone of osteogenesis and angiogenesis is created around it, bone cover is formed. Osteointegration of the implant occurs early, by 7 days after surgery, and by 30 days after surgery organotypical re-modelling of the regenerated bone takes place, as well as the defect is filled with lamellar bone tissue by the type of bone wound primary adhesion. By 30 days after surgery mineral content of the regenerated bone tissue approximates to the composition of intact cortex mineral phase.

FABRICATION OF IN SITUFe-Ti-B COMPOSITE COATING BY LASER CLADDING

NASA Astrophysics Data System (ADS)

Du, Baoshuai

2013-06-01

Laser cladding was applied to deposit in situFe-Ti-B composite coatings on mild carbon steel with precursor of ferrotitanium, ferroboron and pure Fe alloy powders. The composite coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA). Wear resistance of the laser-cladded Fe-Ti-B coatings was evaluated under dry sliding condition at room temperature using block-on-ring wear tester. Results indicate that in situ reinforcements of TiB2 and Fe2B can be synthesized in the Fe-Ti-B coatings. The amount of TiB2 increases with the increase of content of ferrotitanium and ferroboron in the precursor. Reinforcements are formed through the liquid-precipitation route following the solidification path of the Fe-Ti-B system. Hardness and wear properties of the coatings improved significantly in comparison to the as-received substrate due to the presence of hard reinforcements.

The microstructural characterization of an in situ grown Si{sub 3}N{sub 4} whisker-reinforced BAS glass-ceramic matrix composite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Feng; Ortiz-Longo, C.R.; White, K.W.

The microstructure of barium aluminum silicate (BAS)/silicon nitride in situ whisker reinforced ceramic matrix composite was examined by X-ray diffraction, transmission electron microscopy, electron diffraction and energy-dispersive X-ray microanalysis. Although the authors can not conclusively exclude the presence of orthorhombic BAS, hexagonal BAS and both {alpha}-Si{sub 3}N{sub 4} and {beta}-Si{sub 3}N{sub 4} were identified in this material. The {beta}-Si{sub 3}N{sub 4} whiskers nucleate and grow in random directions in the nearly continuous matrix of metastable hexacelsian. The crystallization process of the glass phase can be taken almost to completion but a small proportion of residual glass phase is present atmore » the interface and grains-junction. Both whisker-like and equiaxed {beta}-Si{sub 3}N{sub 4} exist in this material.« less

Improvements in Electron-Probe Microanalysis: Applications to Terrestrial, Extraterrestrial, and Space-Grown Materials

NASA Technical Reports Server (NTRS)

Carpenter, Paul; Armstrong, John

2004-01-01

Improvement in the accuracy of electron-probe microanalysis (EPMA) has been accomplished by critical assessment of standards, correction algorithms, and mass absorption coefficient data sets. Experimental measurement of relative x-ray intensities at multiple accelerating potential highlights errors in the absorption coefficient. The factor method has been applied to the evaluation of systematic errors in the analysis of semiconductor and silicate minds. Accurate EPMA of Martian soil stimulant is necessary in studies that build on Martian rover data in anticipation of missions to Mars.

Analysis of Roman age wall paintings found in Pordenone, Trieste and Montegrotto.

PubMed

Mazzocchin, G A; Agnoli, F; Salvadori, M

2004-10-20

The aim of the present work is the study of many fragments of wall painting from archaeological excavations in three different Roman age sites dating back to the I Century before Common Era: Pordenone (località Torre); Trieste (Crosada) and Padova (Montegrotto). The techniques used were optical microscopy, scanning electron microscopy (SEM), equipped with a EDS microanalysis detector, X-rays powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Fourier transform Raman spectroscopy (FT-Raman) and electron paramagnetic resonance (EPR) spectroscopy. The identified pigments were: cinnabar, hematite, celadonite, glauconite, cuprorivaite (Egyptian blue), yellow and red ochre, calcite, limonite, coal black. In general, the mortar preparation did not correspond to the complex procedure suggested by Vitruvius (De Architectura), but generally showed a porous layer, with crushed grains under the pigment layer. In some cases, two superimposed pigment layers were found: yellow superimposed on both red and pink, black on pink, green on black. The slight differences we found in the use of the pigments in the three studied sites might show that the same technology, culture and taste spread all over the Roman Empire in North Eastern Italy (X(a) Regio Venetia et Histria).

Characterization of leaf-level particulate matter for an industrial city using electron microscopy and X-ray microanalysis.

PubMed

Sgrigna, G; Baldacchini, C; Esposito, R; Calandrelli, R; Tiwary, A; Calfapietra, C

2016-04-01

This study reports application of monitoring and characterization protocol for particulate matter (PM) deposited on tree leaves, using Quercus ilex as a case study species. The study area is located in the industrial city of Terni in central Italy, with high PM concentrations. Four trees were selected as representative of distinct pollution environments based on their proximity to a steel factory and a street. Wash off from leaves onto cellulose filters were characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy, inferring the associations between particle sizes, chemical composition, and sampling location. Modeling of particle size distributions showed a tri-modal fingerprint, with the three modes centered at 0.6 (factory related), 1.2 (urban background), and 2.6μm (traffic related). Chemical detection identified 23 elements abundant in the PM samples. Principal component analysis recognized iron and copper as source-specific PM markers, attributed mainly to industrial and heavy traffic pollution respectively. Upscaling these results on leaf area basis provided a useful indicator for strategic evaluation of harmful PM pollutants using tree leaves. Copyright © 2016. Published by Elsevier B.V.

Structural-Phase States of Fe-Cu and Fe-Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

NASA Astrophysics Data System (ADS)

Lerner, M. I.; Bakina, O. V.; Pervikov, A. V.; Glazkova, E. A.; Lozhkomoev, A. S.; Vorozhtsov, A. B.

2018-05-01

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe-Cu and Fe-Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

Nanocrystalline hydroxyapatite doped with selenium oxyanions: a new material for potential biomedical applications.

PubMed

Kolmas, Joanna; Oledzka, Ewa; Sobczak, Marcin; Nałęcz-Jawecki, Grzegorz

2014-06-01

Selenium-substituted hydroxyapatites containing selenate SeO4(2-) or selenite SeO3(2-) ions were synthesized using a wet precipitation method. The selenium content was determined by atomic absorbance spectrometry. The raw, unsintered powders were also characterized using powder X-ray diffraction, middle-range FT-IR spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopic microanalysis. The synthesized apatites were found to be pure and nanocrystalline with a crystal size similar to that in bone mineral. The incorporation of selenium oxyanions into the crystal lattice was confirmed. The toxicity of hydroxyapatites containing selenite or selenate ions was evaluated with a protozoan assay and bacterial luminescence test. Copyright © 2014 Elsevier B.V. All rights reserved.

Heterodoped nanotubes: theory, synthesis, and characterization of phosphorus-nitrogen doped multiwalled carbon nanotubes.

PubMed

Cruz-Silva, Eduardo; Cullen, David A; Gu, Lin; Romo-Herrera, Jose Manuel; Muñoz-Sandoval, Emilio; López-Urías, Florentino; Sumpter, Bobby G; Meunier, Vincent; Charlier, Jean-Christophe; Smith, David J; Terrones, Humberto; Terrones, Mauricio

2008-03-01

Arrays of multiwalled carbon nanotubes doped with phosphorus (P) and nitrogen (N) are synthesized using a solution of ferrocene, triphenyl-phosphine, and benzylamine in conjunction with spray pyrolysis. We demonstrate that iron phosphide (Fe(3)P) nanoparticles act as catalysts during nanotube growth, leading to the formation of novel PN-doped multiwalled carbon nanotubes. The samples were examined by high resolution electron microscopy and microanalysis techniques, and their chemical stability was explored by means of thermogravimetric analysis in the presence of oxygen. The PN-doped structures reveal important morphology and chemical changes when compared to N-doped nanotubes. These types of heterodoped nanotubes are predicted to offer many new opportunities in the fabrication of fast-response chemical sensors.

Structural-Phase States of Fe–Cu and Fe–Ag Bimetallic Particles Produced by Electric Explosion of Two Wires

NASA Astrophysics Data System (ADS)

Lerner, M. I.; Bakina, O. V.; Pervikov, A. V.; Glazkova, E. A.; Lozhkomoev, A. S.; Vorozhtsov, A. B.

2018-05-01

X-ray phase analysis, transmission electron microscopy, and X-ray microanalysis were used to examine the structural-phase states of Fe-Cu and Fe-Ag bimetallic nanoparticles. The nanoparticles were obtained by the electric explosion of two twisted metal wires in argon atmosphere. It was demonstrated that the nanoparticles have the structure of Janus particles. Presence of the Janus particle structure in the samples indicates formation of binary melt under conditions of combined electric explosion of two wires. Phases based on supersaturated solid solutions were not found in the examined samples. The data obtained allow arguing that it is possible to achieve uniform mixing of the two-wire explosion products under the described experiment conditions.

Tribological properties of TiC/a-C:H nanocomposite coatings prepared via HiPIMS

NASA Astrophysics Data System (ADS)

Sánchez-López, J. C.; Dominguez-Meister, S.; Rojas, T. C.; Colasuonno, M.; Bazzan, M.; Patelli, A.

2018-05-01

High power impulse magnetron sputtering (HiPIMS) technology has been employed to prepare TiC/a-C:H nanocomposite coatings from a titanium target in acetylene (C2H2) reactive atmospheres. Gas fluxes were varied from 1.3 to 4.4 sccm to obtain C/Ti ratios from 2 to 15 as measured by electron probe microanalysis (EPMA). X-ray diffraction and transmission electron microscopy demonstrate the presence of TiC nanocrystals embedded in an amorphous carbon-based matrix. The hardness properties decrease from 17 to 10 GPa as the carbon content increases. The tribological properties were measured using a pin-on-disk tribometer in ambient air (RH = 30-40%) at 10 cm/s with 5 N of applied load against 6-mm 100Cr6 balls. The friction coefficient and the film wear rates are gradually improved from 0.3 and 7 × 10-6 mm3/N m to 0.15 and 2 × 10-7 mm3/N m, respectively, by increasing the C2H2 flux. To understand the tribological processes appearing at the interface and to elucidate the wear mechanism, microstructural and chemical investigations of the coatings were performed before and after the friction test. EPMA, X-ray photoelectron and electron energy-loss spectroscopies were employed to obtain an estimation of the fraction of the a-C:H phase, which can be correlated with the tribological behavior. Examination of the friction counterfaces (ball and track) by Raman microanalysis reveals an increased ordering of the amorphous carbon phase concomitant with friction reduction. The tribological results were compared with similar TiC/a-C(:H) composites prepared by the conventional direct current process.

Analysis of the Henze precipitate from the blood cells of the ascidian Phallusia mammillata

NASA Astrophysics Data System (ADS)

Ciancio, Aurelio; Scippa, Silvia; Nette, Geoffrey; De Vincentiis, Mario

The Henze precipitate, a peculiar blue-green microparticulate obtained by lysis of the blood cells of the ascidian Phallusia mammillata (Protochordata), was investigated with atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray microanalysis. The precipitate was collected from the Henze solution, an unstable red-brown product obtained by treating blood with distilled water, whose degradation yields a characteristic blue-green product. The microparticulates measured 50-100 µm in diameter and appeared irregular in shape. SEM examination showed smooth, roughly round boundaries. The microparticulate surface examined with AFM appeared as an irregular matrix formed by 70-320-nm-wide mammillate composites, including and embedding small (500-800 nm wide) crystal-like multilayered formations. X- ray analysis showed that the elements present in these same precipitates were mainly C, Si, Al and O. The microparticulate composition appeared close to those of natural waxes or lacquers, embedding amorphous silicates and/or other Si-Al components. The unusual occurrence of Si in ascidian blood and its role are discussed.

Local viscoelastic response of direct and indirect dental restorative composites measured by AFM.

PubMed

Grattarola, Laura; Derchi, Giacomo; Diaspro, Alberto; Gambaro, Carla; Salerno, Marco

2018-06-08

We investigated the viscoelastic response of direct and indirect dental restorative composites by the novel technique of AM-FM atomic force microscopy. We selected four composites for direct restorations (Adonis, Optifil, EPH, CME) and three composites for indirect restorations (Gradia, Estenia, Signum). Scanning electron microscopy with micro-analysis was also used to support the results. The mean storage modulus of all composites was in the range of 10.2-15.2 GPa. EPH was the stiffest (p<0.05 vs. all other composites but Adonis and Estenia), while no significant difference was observed between direct and indirect group (p≥0.05). For the loss tangent, Gradia had the highest value (~0.3), different (p<0.05) from Optifil (~0.01) and EPH (~0.04) despite the large coefficient of variation (24%), and the direct composites showed higher loss tangent (p<0.01) than the indirect composites. All composites exhibited minor contrast at the edge of fillers, showing that these are pre-polymerized, as confirmed by EDS.

Spectroscopic, microchemical and petrographic analyses of plasters from ancient buildings in Lamezia Terme (Calabria, Southern Italy)

NASA Astrophysics Data System (ADS)

De Luca, Raffaella; Gigliotti, Valentina; Panarello, Mario; Bloise, Andrea; Crisci, Gino M.; Miriello, Domenico

2016-01-01

This work shows the results of the spectroscopic, microchemical and petrographic study carried out on six plasters coming from three important residential buildings of the 18th century, located in Lamezia Terme (Catanzaro, Southern Italy). To study the provenance of the raw materials used to make the plasters, one sample of limestone and two samples of sand were also collected from the quarries near Lamezia Terme and compared with the historical plasters. Samples were studied by polarized optical microscopy (OM), X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results of these analyses allowed to determine the mineralogical, petrographical and chemical characteristics of the plasters, identify the pigments used for their coloration and provide useful information about the building techniques, the raw materials employed and the production technology of plasters during the 18th century in Lamezia Terme. SEM-EDS microanalysis also revealed the presence of gold and silver on the surface of two samples.

Standardless quantification by parameter optimization in electron probe microanalysis

NASA Astrophysics Data System (ADS)

Limandri, Silvina P.; Bonetto, Rita D.; Josa, Víctor Galván; Carreras, Alejo C.; Trincavelli, Jorge C.

2012-11-01

A method for standardless quantification by parameter optimization in electron probe microanalysis is presented. The method consists in minimizing the quadratic differences between an experimental spectrum and an analytical function proposed to describe it, by optimizing the parameters involved in the analytical prediction. This algorithm, implemented in the software POEMA (Parameter Optimization in Electron Probe Microanalysis), allows the determination of the elemental concentrations, along with their uncertainties. The method was tested in a set of 159 elemental constituents corresponding to 36 spectra of standards (mostly minerals) that include trace elements. The results were compared with those obtained with the commercial software GENESIS Spectrum® for standardless quantification. The quantifications performed with the method proposed here are better in the 74% of the cases studied. In addition, the performance of the method proposed is compared with the first principles standardless analysis procedure DTSA for a different data set, which excludes trace elements. The relative deviations with respect to the nominal concentrations are lower than 0.04, 0.08 and 0.35 for the 66% of the cases for POEMA, GENESIS and DTSA, respectively.

Role of phi cells and the endodermis under salt stress in Brassica oleracea.

PubMed

Fernandez-Garcia, N; Lopez-Perez, L; Hernandez, M; Olmos, E

2009-01-01

Phi cell layers were discovered in the 19th century in a small number of species, including members of the Brassicaceae family. A mechanical role was first suggested for this structure; however, this has never been demonstrated. The main objective of the present work was to analyse the ultrastructure of phi cells, their influence on ion movement from the cortex to the stele, and their contribution to salt stress tolerance in Brassica oleracea. Transmission electron microscopy and X-ray microanalysis studies were used to analyse the subcellular structure and distribution of ions in phi cells and the endodermis under salt stress. Ion movement was analysed using lanthanum as an apoplastic tracer. The ultrastructural results confirm that phi cells are specialized cells showing cell wall ingrowths in the inner tangential cell walls. X-ray microanalysis confirmed a build-up of sodium. Phi thickenings were lignified and lanthanum moved periplasmically at this level. To the best of our knowledge, this is the first study reporting the possible role of the phi cells as a barrier controlling the movement of ions from the cortex to the stele. Therefore, the phi cell layer and endodermis seem to be regulating ion transport in Brassica oleracea under salt stress.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kenik, E.A.

X-ray microanalysis in an analytical electron microscope is a proven technique for the measurement of solute segregation in alloys. Solute segregation under equilibrium or nonequilibrium conditions can strongly influence material performance. X-ray microanalysis in an analytical electron microscope provides an alternative technique to measure grain boundary segregation, as well as segregation to other defects not accessible to Auger analysis. The utility of the technique is demonstrated by measurements of equilibrium segregation to boundaries in an antimony containing stainless steel, including the variation of segregation with boundary character and by measurements of nonequilibrium segregation to boundaries and dislocations in an ion-irradiatedmore » stainless steel.« less

Normal incidence x-ray mirror for chemical microanalysis

DOEpatents

Carr, M.J.; Romig, A.D. Jr.

1987-08-05

An x-ray mirror for both electron column instruments and micro x-ray fluorescence instruments for making chemical, microanalysis comprises a non-planar mirror having, for example, a spherical reflecting surface for x-rays comprised of a predetermined number of alternating layers of high atomic number material and low atomic number material contiguously formed on a substrate and whose layers have a thickness which is a multiple of the wavelength being reflected. For electron column instruments, the wavelengths of interest lie above 1.5nm, while for x-ray fluorescence instruments, the range of interest is below 0.2nm. 4 figs.

Quantitative determination of occupation sites of trace Co substituted for multiple Fe sites in M-type hexagonal ferrite using statistical beam-rocking TEM-EDXS analysis.

PubMed

Ohtsuka, Masahiro; Muto, Shunsuke; Tatsumi, Kazuyoshi; Kobayashi, Yoshinori; Kawata, Tsunehiro

2016-04-01

The occupation sites and the occupancies of trace dopants in La/Co co-doped Sr-M-type ferrite, SrFe12O19, were quantitatively and precisely determined by beam-rocking energy-dispersive X-ray spectroscopy (EDXS) on the basis of electron-channeling effects. Because the Co atoms, in particular, should be partially substituted for the five crystallographically inequivalent sites, which could be key parameters in improving the magneto-crystalline anisotropy, it is difficult yet intriguing to discover their occupation sites and occupancies without using the methods of large-scale facilities, such as neutron diffraction and synchrotron radiation. In the present study, we tackled this problem by applying an extended statistical atom location by channeling enhanced microanalysis method, using conventional transmission electron microscopy, EDXS and dynamical electron elastic/inelastic scattering theories. The results show that the key occupation sites of Co were the 2a, 4f1 and 12k sites. The quantified occupancies of Co were consistent with those of the previous study, which involved a combination of neutron diffraction and extended X-ray absorption fine structure analysis, as well as energetics considerations based on by first-principles calculations. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst.

PubMed

Tripathi, Pranav K; Durbach, Shane; Coville, Neil J

2017-09-22

The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman I D / I G ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst.

Synthesis of Multi-Walled Carbon Nanotubes from Plastic Waste Using a Stainless-Steel CVD Reactor as Catalyst

PubMed Central

Durbach, Shane

2017-01-01

The disposal of non-biodegradable plastic waste without further upgrading/downgrading is not environmentally acceptable and many methods to overcome the problem have been proposed. Herein we indicate a simple method to make high-value nanomaterials from plastic waste as a partial solution to the environmental problem. Laboratory-based waste centrifuge tubes made of polypropylene were chosen as a carbon source to show the process principle. In the process, multi-walled carbon nanotubes (MWCNTs) were synthesized from plastic waste in a two-stage stainless steel 316 (SS 316) metal tube that acted as both reactor vessel and catalyst. The steel reactor contains Fe (and Ni, and various alloys), which act as the catalyst for the carbon conversion process. The reaction and products were studied using electron probe microanalysis, thermogravimetric analysis, Raman spectroscopy and transmission electron microscopy and scanning electron microscopy. Optimization studies to determine the effect of different parameters on the process showed that the highest yield and most graphitized MWCNTs were formed at 900 °C under the reaction conditions used (yield 42%; Raman ID/IG ratio = 0.48). The high quality and high yield of the MWCNTs that were produced in a flow reactor from plastic waste using a two stage SS 316 chemical vapor deposition (CVD) furnace did not require the use of an added catalyst. PMID:28937596

Virgin olive oil blended polyurethane micro/nanofibers ornamented with copper oxide nanocrystals for biomedical applications.

PubMed

Amna, Touseef; Hassan, M Shamshi; Yang, Jieun; Khil, Myung-Seob; Song, Ki-Duk; Oh, Jae-Don; Hwang, Inho

2014-01-01

Recently, substantial interest has been generated in using electrospun biomimetic nanofibers of hybrids, particularly organic/inorganic, to engineer different tissues. The present work, for the first time, introduced a unique natural and synthetic hybrid micronanofiber wound dressing, composed of virgin olive oil/copper oxide nanocrystals and polyurethane (PU), developed via facile electrospinning. The as-spun organic/inorganic hybrid micronanofibers were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis, X-ray diffraction, electron probe microanalysis, and transmission electron microscopy. The interaction of cells with scaffold was studied by culturing NIH 3T3 fibroblasts on an as-spun hybrid micronanofibrous mat, and viability, proliferation, and growth were assessed. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay results and SEM observation showed that the hybrid micronanofibrous scaffold was noncytotoxic to fibroblast cell culture and was found to benefit cell attachment and proliferation. Hence our results suggest the potential utilization of as-spun micronanoscaffolds for tissue engineering. Copper oxide-olive oil/PU wound dressing may exert its positive beneficial effects at every stage during wound-healing progression, and these micronanofibers may serve diverse biomedical applications, such as tissue regeneration, damaged skin treatment, wound healing applications, etc. Conclusively, the fabricated olive oil-copper oxide/PU micronanofibers combine the benefits of virgin olive oil and copper oxide, and therefore hold great promise for biomedical applications in the near future.

Foliar manganese accumulation by Maytenus founieri (Celastraceae) in its native New Caledonian habitats: populational variation and localization by X-ray microanalysis.

PubMed

Fernando, D R; Woodrow, I E; Jaffré, T; Dumontet, V; Marshall, A T; Baker, A J M

2008-01-01

Hyperaccumulation by plants is a rare phenomenon that has potential practical benefits. The majority of manganese (Mn) hyperaccumulators discovered to date occur in New Caledonia, and little is known about their ecophysiology. This study reports on natural populations of one such species, the endemic shrub Maytenus founieri. Mean foliar Mn concentrations of two populations growing on ultramafic substrates with varying soil pHs were obtained. Leaf anatomies were examined by light microscopy, while the spatial distributions of foliar Mn in both populations were examined by qualitative scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Plants growing on two different substrates were found to have very different mean dry weight (DW) foliar Mn concentrations. Light microscopy showed that the leaves had very distinct thick dermal structures, consisting of multiple layers of large cells in the hypodermis. In vivo X-ray microprobe analyses revealed that, in both populations, Mn sequestration occurred primarily in these dermal tissues. The finding here that foliar Mn is most highly localized in the nonphotosynthetic tissues of M. founieri contrasts with results from similar studies on other woody species that accumulate high Mn concentrations in their shoots.

Implications of Polishing Techniques in Quantitative X-Ray Microanalysis

PubMed Central

Rémond, Guy; Nockolds, Clive; Phillips, Matthew; Roques-Carmes, Claude

2002-01-01

Specimen preparation using abrasives results in surface and subsurface mechanical (stresses, strains), geometrical (roughness), chemical (contaminants, reaction products) and physical modifications (structure, texture, lattice defects). The mechanisms involved in polishing with abrasives are presented to illustrate the effects of surface topography, surface and subsurface composition and induced lattice defects on the accuracy of quantitative x-ray microanalysis of mineral materials with the electron probe microanalyzer (EPMA). PMID:27446758

Is scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) quantitative?

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2013-01-01

Scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) is a widely applied elemental microanalysis method capable of identifying and quantifying all elements in the periodic table except H, He, and Li. By following the "k-ratio" (unknown/standard) measurement protocol development for electron-excited wavelength dispersive spectrometry (WDS), SEM/EDS can achieve accuracy and precision equivalent to WDS and at substantially lower electron dose, even when severe X-ray peak overlaps occur, provided sufficient counts are recorded. Achieving this level of performance is now much more practical with the advent of the high-throughput silicon drift detector energy dispersive X-ray spectrometer (SDD-EDS). However, three measurement issues continue to diminish the impact of SEM/EDS: (1) In the qualitative analysis (i.e., element identification) that must precede quantitative analysis, at least some current and many legacy software systems are vulnerable to occasional misidentification of major constituent peaks, with the frequency of misidentifications rising significantly for minor and trace constituents. (2) The use of standardless analysis, which is subject to much broader systematic errors, leads to quantitative results that, while useful, do not have sufficient accuracy to solve critical problems, e.g. determining the formula of a compound. (3) EDS spectrometers have such a large volume of acceptance that apparently credible spectra can be obtained from specimens with complex topography that introduce uncontrolled geometric factors that modify X-ray generation and propagation, resulting in very large systematic errors, often a factor of ten or more. © Wiley Periodicals, Inc.

Ultrastructure and chemical composition of the proboscis hooks of Acanthocephalus lucii (Müller, 1776) (Acanthocephala: Palaeacanthocephala) using X-ray elemental analysis.

PubMed

Brázová, Tímea; Poddubnaya, Larisa G; Miss, Noemí Ramírez; Hanzelová, Vladimíra

2014-12-01

The ultrastructure and chemical composition of the proboscis hooks and surrounding tegument of Acanthocephalus lucii (Müller, 1776), a parasite of European perch, Perca fluviatilis Linnaeus, were examined using scanning (SEM) and transmission (TEM) electron microscopy and X-ray microanalysis (EDXA). The blade of middle hooks consists of three layers: an outer homogeneous layer, an inner heterogeneous layer and a central core. TEM observation revealed the presence of hollow tubes, which spaced the central core; fibrous inner hook layer surrounded by an electron-dense margin and the basal tegumental layer filled with electron-dense bodies and outer layer. We found for the first time that the so-called 'epidermal covering' surrounding of the exposed hook blade (outer hook layer) is a modified striped portion of the tegumental layer and there are no special contact sites between these two morphologically different structures, i.e. striped layer of the syncytial tegument and following proper outer hook layer, which is a homogeneous, moderately electron-dense layer of -0.3 μm in thickness. The hook root is embedded into subtegumental fibrous layer. X-ray microanalysis of both the surface and internal parts of A. lucii hooks demonstrated the presence of calcium, magnesium, phosphorus and sulphur. The highest concentration of sulphur was recorded at the tip of hooks, whereas the middle part of the hooks was most rich in calcium, phosphorus and magnesium. The proximal part of the hooks contained lower concentrations of sulphur, calcium and phosphorus. In the proboscis tegument, only two elements, calcium and silicon, were found. The differences observed in the chemical composition of the hook 'epidermal covering' and the proboscis tegument support our ultrastructural findings that the hook tegumental covering is a modified structure compared with that of the general proboscis tegument.

Diagnosis of electrocution: The application of scanning electron microscope and energy-dispersive X-ray spectroscopy in five cases.

PubMed

Visonà, S D; Chen, Y; Bernardi, P; Andrello, L; Osculati, A

2018-03-01

Deaths from electricity, generally, do not have specific findings at the autopsy. The diagnosis is commonly based on the circumstances of the death and the morphologic findings, above all the current mark. Yet, the skin injury due to an electrocution and other kinds of thermal injuries often cannot be differentiated with certainty. Therefore, there is a great interest in finding specific markers of electrocution. The search for the metallization of the skin through Scanning Electron Microscope equipped with Energy Dispersive X-Ray Spectroscopy (EDS) probe is of special importance in order to achieve a definite diagnosis in case of suspected electrocution. We selected five cases in which the electrocution was extremely likely considering the circumstances of the death. In each case a forensic autopsy was performed. Then, the skin specimens were stained with Hematoxylin Eosin and Perls. On the other hand, the skin lesions were examined with a scanning electron microscope equipped with EDS probe in order to evaluate the morphological ultrastructural features and the presence of deposits on the surface of the skin. The typical skin injury of the electrocution (current mark) were macroscopically detected in all of the cases. The microscopic examination of the skin lesions revealed the typical spherical vacuoles in the horny layer and, in the epidermis, the elongation of the cell nuclei as well as necrosis. Perls staining was negative in 4 out 6 cases. Ultrastructural morphology revealed the evident vacuolization of the horny layer, elongation of epidermic cells, coagulation of the elastic fibers. In the specimens collected from the site of contact with the conductor of case 1 and 2, the presence of the Kα peaks of iron was detected. In the corresponding specimens taken from cases 2, 4, 5 the microanalysis showed the Kα peaks of titanium. In case 3, titanium and carbon were found. In the suspicion of electrocution, the integrated use of different tools is recommended, including macroscopic observation, H&E staining, iron-specific staining, scanning electron microscopy and EDS microanalysis. Only the careful interpretation of the results provided by all these methods can allow the pathologist to correctly identify the cause of the death. Particularly, the present study suggests that the microanalysis (SEM-EDS) represents a very useful tool for the diagnosis of electrocution, allowing the detection and the identification of the metals embedded in the skin and their evaluation in the context of the ultrastructural morphology. Copyright © 2018. Published by Elsevier B.V.

Surface characterization of stainless HP-40 steel using laser induced μ-breakdown spectroscopy (μ -LIBS)

NASA Astrophysics Data System (ADS)

Pinto, M.; Calderón, X.; Mejía Ospino, E.; Cabanzo, R.; Poveda, Juan C.

2016-02-01

In the present study, optical microscopy in stereoscopic mode coupled to laser- induced p-breakdown spectroscopy (μ-LIBS) was applied for analysing HP-40 steel samples. microLIBS (μ-LIBS) is a new growing area that employs low energy laser pulses for the generation of plasma emission, which allow the realization of localized microanalysis [1]. This new LIBS instrument was used for the surface characterization of the steel samples in the spectral range from 356 to 401nm. Elements such as Cr, Ni, Fe, Nb, Pb, Mo, C, Mn and Si in the steel samples were investigated. The results allowed the construction of elemental distribution profiles of the samples. Complementary the HP-40 steel samples were superficially characterized by Scanning Electron Microscope (SEM).

The concept of the phases ratio control during the formation of composite filamentary nanocrystals xInSe-(1-x)In2O3 on glass substrates

NASA Astrophysics Data System (ADS)

Gasanly, S. A.; Tomaev, V. V.; Stoyanova, T. V.

2017-11-01

The method of vacuum deposition on substrates of glass marks the C-29 series PbSe deposited film and the film In the area 3x3 mm2 and a thickness of ˜1 μm. Films are oxidized in dry air at a temperature of 550 °C. Based on studies by X-ray microanalysis and scanning electron microscopy shows the principal possibility of formation of nanowires xInSe-(1-x)In2O3 on the PbSe/In structure. The results allowed to formulate the concept of the control of phases ratio in the forming nanowires xInSe-(1-x)In2O3 on glass substrates.

PREFACE: EMAS 2013 Workshop: 13th European Workshop on Modern Developments and Applications in Microbeam Analysis

NASA Astrophysics Data System (ADS)

Llovet, Xavier, Dr; Matthews, Mr Michael B.; Brisset, François, Dr; Guimarães, Fernanda, Dr; Vieira, Professor Joaquim M., Dr

2014-03-01

This volume of the IOP Conference Series: Materials Science and Engineering contains papers from the 13th Workshop of the European Microbeam Analysis Society (EMAS) on Modern Developments and Applications in Microbeam Analysis which took place from the 12th to the 16th of May 2013 in the Centro de Congressos do Alfândega, Porto, Portugal. The primary aim of this series of workshops is to assess the state-of-the-art and reliability of microbeam analysis techniques. The workshops also provide a forum where students and young scientists starting out on a career in microbeam analysis can meet and discuss with the established experts. The workshops have a very specific format comprising invited plenary lectures by internationally recognized experts, poster presentations by the participants and round table discussions on the key topics led by specialists in the field. This workshop was organized in collaboration with LNEG - Laboratório Nacional de Energia e Geologia and SPMICROS - Sociedade Portuguesa de Microscopia. The technical programme included the following topics: electron probe microanalysis, future technologies, electron backscatter diffraction (EBSD), particle analysis, and applications. As at previous workshops there was also a special oral session for young scientists. The best presentation by a young scientist was awarded with an invitation to attend the 2014 Microscopy and Microanalysis meeting at Hartford, Connecticut. The prize went to Shirin Kaboli, of the Department of Metals and Materials Engineering of McGill University (Montréal, Canada), for her talk entitled ''Plastic deformation studies with electron channelling contrast imaging and electron backscattered diffraction''. The continuing relevance of the EMAS workshops and the high regard in which they are held internationally can be seen from the fact that 74 posters from 21 countries were on display at the meeting and that the participants came from as far away as Japan, Canada and the USA. A selection of participants with posters was invited to give a short oral presentation of their work in three dedicated sessions. The prize for the best poster was an invitation to participate in the 22nd Australian Conference on Microscopy and Microanalysis (ACMM 23) at Adelaide, South Australia. The prize was awarded to Pierre Burdet of the EM Group of the Department of Materials Science and Metallurgy of the University of Cambridge (UK), for the poster entitled: ''3D EDS microanalysis by FIB-SEM: advantages of a low take-off angle''. This proceedings volume contains the full texts of 8 of the invited plenary lectures and of 13 papers on related topics originating from the posters presented at the workshop. All the papers have been subjected to peer review by a least two referees. January 2014 Acknowledgements On behalf of the European Microbeam Analysis Society I would like to thank all the invited speakers, session chairs and members of the discussion panels for making the meeting such a great success. Special thanks go to Fernanda Guimarães and Luc Van't dack who directed the organisation of the workshop giving freely of their time and talents. As was the case for previous workshops, the EMAS board in corpore was responsible for the scientific programme. The Workshop also included a commercial exhibition where many leading instrument suppliers were represented. Several companies that exhibited provided financial support, either by sponsoring an event or by advertising. Below, in alphabetical order, is a list of exhibiting companies and sponsors of the workshop. - Ametek GmbH, Edax Business Unit- IZASA Group Werfen - Bruker Nano GmbH- Jeol (Europe) SAS - Cameca SA- Porto Gran Cruz - Câmara Municipal do Porto- Oxford Instruments NanoAnalysis Ltd. - European Institute for Transuranium Elements (Germany)- Probe Software, Inc. - FEI Company- Tescan, a.s. Michael B Matthews EMAS President

Microstructural characterisation of Al-Si cast alloys containing rare earth additions

NASA Astrophysics Data System (ADS)

Elgallad, E. M.; Ibrahim, M. F.; Doty, H. W.; Samuel, F. H.

2018-05-01

This paper presents a thorough study on the effect of rare earth elements, specifically La and Ce, on the microstructure characteristics of non-modified and Sr-modified A356 and A413 alloys. Several alloys were prepared by adding 1% La and 1% Ce either individually or in combination. Microstructural characterisation was carried out using optical microscopy, scanning electron microscopy and electron probe microanalysis as well as differential scanning calorimetry (DSC) analysis. The results showed that the individual and combined additions of La and Ce did not bring about any modification or even refinement in the eutectic Si structure. Moreover, these additions were found to negate the modification effect of Sr, particularly in the presence of La. The A356 and A413 alloys containing La and/or Ce displayed high phase volume fractions owing to the formation of Al-Si-La/Ce/(La,Ce) and Al-Ti-La/Ce intermetallic phases. DSC analysis revealed that the formation temperatures of these phases varied from 560 to 568 °C and 568 to 574 °C, respectively. This analysis also showed that the addition of La and Ce whether individually or in combination resulted in a depression in the eutectic temperature and a considerable increase in the solidification range, particularly for the A413 alloy.

Study of the specific features of single-crystal boron microstructure

NASA Astrophysics Data System (ADS)

Blagov, A. E.; Vasil'ev, A. L.; Dmitriev, V. P.; Ivanova, A. G.; Kulikov, A. G.; Marchenkov, N. V.; Popov, P. A.; Presnyakov, M. Yu.; Prosekov, P. A.; Pisarevskii, Yu. V.; Targonskii, A. V.; Chernaya, T. S.; Chernyshov, D. Yu.

2017-09-01

A complex study of the structure of β-boron single crystal grown by the floating-zone method, with sizes significantly exceeding the analogs known in the literature, has been performed. The study includes X-ray diffraction analysis and X-ray diffractometry (measurement of pole figures and rocking curves), performed on both laboratory and synchrotron sources; atomic-resolution scanning transmission electron microscopy with spherical aberration correction; and energy-dispersive microanalysis. X-ray diffraction analysis using synchrotron radiation has been used to refine the β-boron structure and find impurity Si atoms. The relative variations in the unit-cell parameters a and c for the crystal bulk are found to be δ a/ a ≈ 0.4 and δ c/ c ≈ 0.1%. X-ray diffractometry has revealed that the single-crystal growth axis coincides with the [2\\bar 2013] crystallographic axis and makes an angle of 21.12° with the [0001] threefold axis. Electron microscopy data have confirmed that the sample under study is a β-boron crystal, which may contain 0.3-0.4 at % Si as an impurity. Planar defects (stacking faults and dislocations) are found. The results of additional measurements of the temperature dependence of the thermal conductivity of the crystal in the range of 50-300 K are indicative of its high structural quality.

Experimental Investigation and Analytical Prediction of σ-Phase Precipitation in AISI 316L Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Sahlaoui, Habib; Sidhom, Habib

2013-07-01

The phase precipitation in industrial AISI 316L stainless steel during aging for up to 80,000 hours between 823 K and 1073 K (550 °C and 800 °C) has been studied using transmission electron microscopy, scanning transmission electron microscopy, and carbon replica energy-dispersive X-ray microanalysis. Three phases were identified: Chromium carbides (M23C6), Laves phase ( η), and σ-phase (Fe-Cr). M23C6 carbide precipitation occurred firstly and was followed by the η and σ-phases at grain boundaries when the aging temperature is higher than 873 K (600 °C). Precipitation and growth of M23C6 create chromium depletion zones at the grain boundaries and also retard the σ-phase formation. Thus, the σ-phase is controlled by the kinetic of chromium bulk diffusion and can appear only when the chromium reaches, at grain boundaries and at the M23C6/ γ and M23C6/ η/ γ interfaces, content higher than a critical value obtained by self-healing. An analytical model, based on equivalent chromium content, has been established in this study and successfully validated to predict the time-temperature-precipitation diagram of the σ-phase. The obtained diagram is in good agreement with the experimental results.

Laser Processing of Metals and Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singaravelu, Senthilraja

2012-05-01

A laser offers a unique set of opportunities for precise delivery of high quality coherent energy. This energy can be tailored to alter the properties of material allowing a very flexible adjustment of the interaction that can lead to melting, vaporization, or just surface modification. Nowadays laser systems can be found in nearly all branches of research and industry for numerous applications. Sufficient evidence exists in the literature to suggest that further advancements in the field of laser material processing will rely significantly on the development of new process schemes. As a result they can be applied in various applicationsmore » starting from fundamental research on systems, materials and processes performed on a scientific and technical basis for the industrial needs. The interaction of intense laser radiation with solid surfaces has extensively been studied for many years, in part, for development of possible applications. In this thesis, I present several applications of laser processing of metals and polymers including polishing niobium surface, producing a superconducting phase niobium nitride and depositing thin films of niobium nitride and organic material (cyclic olefin copolymer). The treated materials were examined by scanning electron microscopy (SEM), electron probe microanalysis (EPMA), atomic force microscopy (AFM), high resolution optical microscopy, surface profilometry, Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD). Power spectral density (PSD) spectra computed from AFM data gives further insight into the effect of laser melting on the topography of the treated niobium.« less

Probing Individual Ice Nucleation Events with Environmental Scanning Electron Microscopy

NASA Astrophysics Data System (ADS)

Wang, Bingbing; China, Swarup; Knopf, Daniel; Gilles, Mary; Laskin, Alexander

2016-04-01

Heterogeneous ice nucleation is one of the processes of critical relevance to a range of topics in the fundamental and the applied science and technologies. Heterogeneous ice nucleation initiated by particles proceeds where microscopic properties of particle surfaces essentially control nucleation mechanisms. Ice nucleation in the atmosphere on particles governs the formation of ice and mixed phase clouds, which in turn influence the Earth's radiative budget and climate. Heterogeneous ice nucleation is still insufficiently understood and poses significant challenges in predictive understanding of climate change. We present a novel microscopy platform allowing observation of individual ice nucleation events at temperature range of 193-273 K and relative humidity relevant for ice formation in the atmospheric clouds. The approach utilizes a home built novel ice nucleation cell interfaced with Environmental Scanning Electron Microscope (IN-ESEM system). The IN-ESEM system is applied for direct observation of individual ice formation events, determining ice nucleation mechanisms, freezing temperatures, and relative humidity onsets. Reported microanalysis of the ice nucleating particles (INP) include elemental composition detected by the energy dispersed analysis of X-rays (EDX), and advanced speciation of the organic content in particles using scanning transmission x-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). The performance of the IN-ESEM system is validated through a set of experiments with kaolinite particles with known ice nucleation propensity. We demonstrate an application of the IN-ESEM system to identify and characterize individual INP within a complex mixture of ambient particles.

Influence of microstructure on hardness of plasma sprayed Al2O3-TiO2-MgO coatings with interface diffusion by heat treatment

NASA Astrophysics Data System (ADS)

Chen, Kunlun; Song, Peng; Li, Chao; Lu, Jiansheng

2017-12-01

The effect of heat treatment on the microstructure and mechanical properties of Al2O3-TiO2 coatings doped with 5 wt% MgO was investigated in this paper. The composite coatings were prepared by atmospheric plasma spraying (APS) and heat treated at 1000 °C for 24 h in Ar. The coatings were analyzed using scanning electron microscopy with electron probe x-ray microanalysis and x-ray diffraction. The hardness was determined using a Vickers hardness test on the as-sprayed coatings and after heat treatment. The results showed that the interface diffusion between the Al-rich and Ti-rich layers resulted in mutual pinning within the coating during the heat treatment. The newly formed MgAl2O4 phase promoted cracking-healing behavior within the coating. We conclude that increase of the hardness of the coatings was mainly caused by the mutual pinning interface and crack healing.

Influence of lead ions on the macromorphology of electrodeposited zinc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsuda, Tetsuaki; Tobias, Charles W.

1981-09-01

The morphology of zinc as it is electrodeposited from acid solutions demonstrates a remarkable imprint of electrolyte flow conditions. The development of macromorphology of zinc deposits has been investigated under galvanostatic conditions on a rotating plantinum disk electrode by use of photomacrography, scanning electron microscopy, electron probe microanalysis and Auger microprobe analysis. Logarithmic spiral markings, which reflect the hydrodynamic flow on a rotating disk, appear in a certain region of current density well below the limiting current density. Morphological observations revealed the major influence of trace lead ions on the amplifications of surface roughness through coalescence and preferred growth ofmore » initial protrusions. Results obtained from ultra-pure electrolyte suggest preferred crystal growth towards well-mixed orientation in the concentration field caused by slight differences in crystallization overpotential. A qualitative model involving a coupling mechanism between the evolving surface roughness and instability phenomena in the boundary layer is advanced to explain the formation of spiral patterns.« less

The osteoplastic effectiveness of the implants made of mesh titanium nickelide constructs

PubMed Central

Irianov, Iurii Mikhailovich; Diuriagina, Olga Vladimirovna; Karaseva, Tatiana Iurevna; Karasev, Evgenii Anatolevich

2014-01-01

The purpose of the work was to study the features of reparative osteogenesis for filling the defect of tubular bone under implantation of mesh titanium nickelide constructs. Tibial fenestrated defect was modeled experimentally in 30 Wistar pubertal rats, followed by implant intramedullary insertion. The techniques of radiography, scanning electron microscopy and X-ray electron probe microanalysis were used. The mesh implant of titanium nickelide has been established to possess biocompatibility, osteoconductive and osteoinductive properties, the zone of osteogenesis and angiogenesis is created around it, bone cover is formed. Osteointegration of the implant occurs early, by 7 days after surgery, and by 30 days after surgery organotypical re-modelling of the regenerated bone takes place, as well as the defect is filled with lamellar bone tissue by the type of bone wound primary adhesion. By 30 days after surgery mineral content of the regenerated bone tissue approximates to the composition of intact cortex mineral phase. PMID:24579962

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Acidocalcisomes of Phytomonas françai possess distinct morphological characteristics and contain iron.

PubMed

Miranda, Kildare; Rodrigues, Claudia O; Hentchel, Joachim; Vercesi, Anibal; Plattner, Helmut; de Souza, Wanderley; Docampo, Roberto

2004-10-01

Acidocalcisomes are acidic calcium storage compartments described initially in trypanosomatid and apicomplexan parasites, and recently found in other unicellular eukaryotes. The aim of this study was to identify the presence of acidocalcisomes in the plant trypanosomatid Phytomonas françai. Electron-dense organelles of P. françai were shown to contain large amounts of oxygen, sodium, magnesium, phosphorus, potassium, calcium, iron, and zinc as determined by X-ray microanalysis, either in situ or when purified using iodixanol gradient centrifugation or by elemental mapping. The presence of iron is not common in other acidocalcisomes. In situ, but not when purified, these organelles showed an elongated shape differing from previously described acidocalcisomes. However, these organelles also possessed a vacuolar H+-pyrophosphatase (V-H+-PPase) as determined by biochemical methods and by immunofluorescence microscopy using antibodies against the enzyme. Together, these results suggest that the electron-dense organelles of P. françai are homologous to the acidocalcisomes described in other trypanosomatids, although with distinct morphology and elemental content.

Influence of heat treatment on microstructure and hot crack susceptibility of laser-drilled turbine blades made from Rene 80

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osterle, W.; Krause, S.; Moelders, T.

2008-11-15

Turbine components from conventionally cast nickel-base alloy Rene 80 show different hot cracking susceptibilities depending on their heat treatment conditions leading to slightly different microstructures. Electron probe micro-analysis, focused ion beam technique and analytical transmission electron microscopy were applied to reveal and identify grain boundary precipitates and the {gamma}-{gamma}'-microstructure. The distribution of borides along grain boundaries was evaluated statistically by quantitative metallography. The following features could be correlated with an increase of cracking susceptibility: i) Increasing grain size, ii) increasing fraction of grain boundaries with densely spaced borides, iii) lack of secondary {gamma}'-particles in matrix channels between the coarse cuboidalmore » {gamma}'-precipitates. The latter feature seems to be responsible for linking-up of cracked grain boundary precipitates which occurred as an additional cracking mechanism after one heat treatment, whereas decohesion at the boride-matrix-interface in the heat affected zone of laser-drilled holes was observed for both heat treatments.« less

High-strength bioresorbable Fe-Ag nanocomposite scaffolds: Processing and properties

NASA Astrophysics Data System (ADS)

Sharipova, Aliya; Psakhie, Sergey G.; Swain, Sanjaya K.; Gutmanas, Elazar Y.; Gotman, Irena

2015-10-01

High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na2SO4 and K2CO3 salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy's law. Scaffolds with 50% and 55% porosity exhibited high compressive strength (18-22 MPa), compressive strength of 8-12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6-6 cm2) is close to the range of trabecular bone.

Glass Formation, Phase Equilibria, and Thermodynamic Assessment of the Al-Ce-Co System Assisted by First-Principles Energy Calculations

NASA Astrophysics Data System (ADS)

Gao, Michael C.; Ünlü, Necip; Mihalkovic, Marek; Widom, Michael; Shiflet, G. J.

2007-10-01

This study investigates glass formation, phase equilibria, and thermodynamic descriptions of the Al-rich Al-Ce-Co ternary system using a novel approach that combines critical experiments, CALPHAD modeling, and first-principles (FP) calculations. The glass formation range (GFR) and a partial 500 °C isotherm are determined using a range of experimental techniques including melt spinning, transmission electron microscopy (TEM), electron probe microanalysis (EPMA), X-ray diffraction, and differential thermal analysis (DTA). Three stable ternary phases are confirmed, namely, Al8CeCo2, Al4CeCo, and AlCeCo, while a metastable phase, Al5CeCo2, was discovered. The equilibrium and metastable phases identified by the present and earlier reported experiments, together with many hypothetical ternary compounds, are further studied by FP calculations. Based on new experimental data and FP calculations, the thermodynamics of the Al-rich Al-Co-Ce system is optimized using the CALPHAD method. Application to glass formation is discussed in light of present studies.

Preparation of nanostructured and nanosheets of MoS2 oxide using oxidation method.

PubMed

Amini, Majed; Ramazani S A, Ahmad; Faghihi, Morteza; Fattahpour, Seyyedfaridoddin

2017-11-01

Molybdenum disulfide (MoS 2 ), a two-dimensional transition metal has a 2D layered structure and has recently attracted attention due to its novel catalytic properties. In this study, MoS 2 has been successfully intercalated using chemical and physical intercalation techniques, while enhancing its surface properties. The final intercalated MoS 2 is of many interests because of its low-dimensional and potential properties in in-situ catalysis. In this research, we report different methods to intercalate the layers of MoS 2 successfully using acid-treatment, ultrasonication, oxidation and thermal shocking. The other goal of this study is to form SO bonds mainly because of expected enhanced in-situ catalytic operations. The intercalated MoS 2 is further characterized using analyses such as Fourier Transform Infrared Spectroscopy (FTIR), Raman, Contact Angle, X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Microanalysis (EDAX), Transmission electron microscopy (TEM), and BET. Copyright © 2017. Published by Elsevier B.V.

Evolution of Akaganeite in Rust Layers Formed on Steel Submitted to Wet/Dry Cyclic Tests

PubMed Central

Ye, Wei; Song, Xiaoping; Ma, Yuantai; Li, Ying

2017-01-01

The evolution of akaganeite in rust layers strongly impacts the atmospheric corrosion behavior of steel during long-term exposure; however, the factors affecting the evolution of akaganeite and its mechanism of formation are vague. In this work, wet-dry cyclic corrosion tests were conducted to simulate long-term exposure. Quantitative X-ray diffraction analysis was employed to analyze variations in the relative amounts of akaganeite; scanning electron microscopy and electron probe microanalysis were used to study the migration of relevant elements in the rust layer, which could help elucidate the mechanism of akaganeite evolution. The results indicate that the fraction of akaganeite tends to decrease as the corrosion process proceeded, which is a result of the decrease in the amount of soluble chloride available and the ability of the thick rust layer to block the migration of relevant ions. This work also explores the location of akaganeite formation within the rust layer. PMID:29099061

Corrosion behavior of low alloy steels in a wet-dry acid humid environment

NASA Astrophysics Data System (ADS)

Zhao, Qing-he; Liu, Wei; Yang, Jian-wei; Zhu, Yi-chun; Zhang, Bin-li; Lu, Min-xu

2016-09-01

The corrosion behavior of corrosion resistant steel (CRS) in a simulated wet-dry acid humid environment was investigated and compared with carbon steel (CS) using corrosion loss, polarization curves, X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), N2 adsorption, and X-ray photoelectron spectroscopy (XPS). The results show that the corrosion kinetics of both steels were closely related to the composition and compactness of the rust, and the electrochemical properties of rusted steel. Small amounts of Cu, Cr, and Ni in CRS increased the amount of amorphous phases and decreased the content of γ-FeOOH in the rust, resulting in higher compactness and electrochemical stability of the CRS rust. The elements Cu, Cr, and Ni were uniformly distributed in the CRS rust and formed CuFeO2, Cu2O, CrOOH, NiFe2O4, and Ni2O3, which enhanced the corrosion resistance of CRS in the wet-dry acid humid environment.

Contribution of a new generation field-emission scanning electron microscope in the understanding of a 2099 Al-Li alloy.

PubMed

Brodusch, Nicolas; Trudeau, Michel; Michaud, Pierre; Rodrigue, Lisa; Boselli, Julien; Gauvin, Raynald

2012-12-01

Aluminum-lithium alloys are widespread in the aerospace industry. The new 2099 and 2199 alloys provide improved properties, but their microstructure and texture are not well known. This article describes how state-of-the-art field-emission scanning electron microscopy (FE-SEM) can contribute to the characterization of the 2099 aluminum-lithium alloy and metallic alloys in general. Investigations were carried out on bulk and thinned samples. Backscattered electron imaging at 3 kV and scanning transmission electron microscope imaging at 30 kV along with highly efficient microanalysis permitted correlation of experimental and expected structures. Although our results confirm previous studies, this work points out possible substitutions of Mg and Zn with Li, Al, and Cu in the T1 precipitates. Zinc and magnesium are also present in "rice grain"-shaped precipitates at the grain boundaries. The versatility of the FE-SEM is highlighted as it provides information in the macro- and microscales with relevant details. Its ability to probe the distribution of precipitates from nano- to microsizes throughout the matrix makes FE-SEM an essential technique for the characterization of metallic alloys.

Influence of microstructure on superconductivity in KxFe2−ySe2 and evidence for a new parent phase K2Fe7Se8

PubMed Central

Ding, Xiaxin; Fang, Delong; Wang, Zhenyu; Yang, Huan; Liu, Jianzhong; Deng, Qiang; Ma, Guobin; Meng, Chong; Hu, Yuhui; Wen, Hai-Hu

2013-01-01

The search for new superconducting materials has been spurred on by the discovery of iron-based superconductors whose structure and composition is qualitatively different from the cuprates. The study of one such material, KxFe2−ySe2 with a critical temperature of 32 K, is made more difficult by the fact that it separates into two phases—a dominant antiferromagnetic insulating phase K2Fe4Se5, and a minority superconducting phase whose precise structure is as yet unclear. Here we perform electrical and magnetization measurements, scanning electron microscopy and microanalysis, X-ray diffraction and scanning tunnelling microscopy on KxFe2−ySe2 crystals prepared under different quenching processes to better understand the relationship between its microstructure and its superconducting phase. We identify a three-dimensional network of superconducting filaments within this material and present evidence to suggest that the superconducting phase consists of a single Fe vacancy for every eight Fe-sites arranged in a √8 x √10 parallelogram structure. PMID:23695691

A Comparison of Experimental EPMA Data and Monte Carlo Simulations

NASA Technical Reports Server (NTRS)

Carpenter, P. K.

2004-01-01

Monte Carlo (MC) modeling shows excellent prospects for simulating electron scattering and x-ray emission from complex geometries, and can be compared to experimental measurements using electron-probe microanalysis (EPMA) and phi(rho z) correction algorithms. Experimental EPMA measurements made on NIST SRM 481 (AgAu) and 482 (CuAu) alloys, at a range of accelerating potential and instrument take-off angles, represent a formal microanalysis data set that has been used to develop phi(rho z) correction algorithms. The accuracy of MC calculations obtained using the NIST, WinCasino, WinXray, and Penelope MC packages will be evaluated relative to these experimental data. There is additional information contained in the extended abstract.

Scanning Electron Microscopy and Energy-Dispersive X-Ray Microanalysis of Set CEM Cement after Application of Different Bleaching Agents.

PubMed

Samiei, Mohammad; Janani, Maryam; Vahdati, Amin; Alemzadeh, Yalda; Bahari, Mahmoud

2017-01-01

The present study evaluated the element distribution in completely set calcium-enriched mixture (CEM) cement after application of 35% carbamide peroxide, 40% hydrogen peroxide and sodium perborate as commercial bleaching agents using an energy-dispersive x-ray microanalysis (EDX) system. The surface structure was also observed using the scanning electron microscope (SEM). Twenty completely set CEM cement samples, measuring 4×4 mm 2 , were prepared in the present in vitro study and randomly divided into 4 groups based on the preparation technique as follows: the control group; 35% carbamide peroxide group in contact for 30-60 min for 4 times; 40% hydrogen peroxide group with contact time of 15-20 min for 3 times; and sodium perborate group, where the powder and liquid were mixed and placed on CEM cement surface 4 times. Data were analyzed at a significance level of 0.05 through the one Way ANOVA and Tukey's post hoc tests. EDX showed similar element distribution of oxygen, sodium, calcium and carbon in CEM cement with the use of carbamide peroxide and hydroxide peroxide; however, the distribution of silicon was different ( P <0.05). In addition, these bleaching agents resulted in significantly higher levels of oxygen and carbon ( P <0.05) and a lower level of calcium ( P <0.05) compared to the control group. SEM of the control group showed plate-like and globular structure. Sodium perborate was similar to control group due to its weak oxidizing properties. Globular structures and numerous woodpecker holes were observed on the even surface on the carbamide peroxide group. The mean elemental distribution of completely set CEM cement was different when exposed to sodium perborate, carbamide peroxide and hydrogen peroxide.

MICRO/NANO-STRUCTURAL EXAMINATION AND FISSION PRODUCT IDENTIFICATION IN NEUTRON IRRADIATED AGR-1 TRISO FUEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

van Rooyen, I. J.; Lillo, T. M.; Wen, H. M.

Advanced microscopic and microanalysis techniques were developed and applied to study irradiation effects and fission product behavior in selected low-enriched uranium oxide/uranium carbide TRISO-coated particles from fuel compacts in six capsules irradiated to burnups of 11.2 to 19.6% FIMA. Although no TRISO coating failures were detected during the irradiation, the fraction of Ag-110m retained in individual particles often varied considerably within a single compact and at the capsule level. At the capsule level Ag-110m release fractions ranged from 1.2 to 38% and within a single compact, silver release from individual particles often spanned a range that extended from 100% retentionmore » to nearly 100% release. In this paper, selected irradiated particles from Baseline, Variant 1 and Variant 3 type fueled TRISO coated particles were examined using Scanning Electron Microscopy, Atom Probe Tomography; Electron Energy Loss Spectroscopy; Precession Electron Diffraction, Transmission Electron Microscopy, Scanning Transmission Electron Microscopy (STEM), High Resolution Electron Microscopy (HRTEM) examinations and Electron Probe Micro-Analyzer. Particle selection in this study allowed for comparison of the fission product distribution with Ag retention, fuel type and irradiation level. Nano sized Ag-containing features were predominantly identified in SiC grain boundaries and/or triple points in contrast with only two sitings of Ag inside a SiC grain in two different compacts (Baseline and Variant 3 fueled compacts). STEM and HRTEM analysis showed evidence of Ag and Pd co-existence in some cases and it was found that fission product precipitates can consist of multiple or single phases. STEM analysis also showed differences in precipitate compositions between Baseline and Variant 3 fuels. A higher density of fission product precipitate clusters were identified in the SiC layer in particles from the Variant 3 compact compared with the Variant 1 compact. Trend analysis shows precipitates were randomly distributed along the perimeter of the IPyC-SiC interlayer but only weakly associated with kernel protrusion and buffer fractures. There has been no evidence that the general release of silver is related to cracks or significant degradation of the microstructure. The results presented in this paper provide new insights to Ag transport mechanism(s) in intact SiC layer of TRISO coated particles.« less

Bladder stone in a human female: The case of an abnormally located intrauterine contraceptive device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, S.R.; Wilkinson, E.J.

A single 4.7 x 3.3 x 1.5 cm solid nodule was removed from the bladder of a 24 years old white female who had lost an intrauterine contraceptive device (IUD) installed approximately four years ago. The nodule showed no external evidence of an IUD or its string. An examination of the nodular surface by scanning electron microscopy (SEM) showed mostly amorphous material with some adherent filamentous structures. Its energy dispersive x-ray microanalysis revealed the presence of calcium and phosphorus suggesting that the nodule was actually a urolith. Fracturing the nodule exposed an embedded entity consistent with being a copper IUD.more » Apparently, the lost IUD had migrated from the uterus into the bladder where it became mineralized. Thus the solid nodule was actually a foreign body stone.« less

Structural investigation of cooperite (PtS) crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rozhdestvina, V. I., E-mail: veronika@ascnet.ru; Udovenko, A. A.; Rubanov, S. V.

2016-03-15

The single-crystal structure of cooperite, a natural platinum sulfide PtS, is studied by X-ray diffraction supported by high-resolution scanning transmission electron microscopy and X-ray spectrum microanalysis. It is found that, in addition to the main reflections corresponding to the known tetragonal cell (a = 3.47 and c = 6.11 Å; space group P4{sub 2}/mmc), many weak reflections with intensities I ≤ 60σ(I) are clearly observed. These reflections fit the tetragonal cell (space group I4/mmm) with doubled parameters. In structures with small (P4{sub 2}/mmc) and large (I4/mmm) cells, the S atoms occupy statistically two special positions. It is shown that themore » chemical composition of the cooperite crystals deviates from the stoichiometric composition: sulfur-deficient specimens predominate.« less

Synthesis, Characterization and Biological Studies of New Linear Thermally Stable Schiff Base Polymers with Flexible Spacers.

PubMed

Qureshi, Farah; Khuhawar, Muhammad Yar; Jahangir, Taj Muhammad; Channar, Abdul Hamid

2016-01-01

Five new linear Schiff base polymers having azomethine structures, ether linkages and extended aliphatic chain lengths with flexible spacers were synthesized by polycondensation of dialdehyde (monomer) with aliphatic and aromatic diamines. The formation yields of monomer and polymers were obtained within 75-92%. The polymers with flexible spacers of n-hexane were somewhat soluble in acetone, chloroform, THF, DMF and DMSO on heating. The monomer and polymers were characterized by melting point, elemental microanalysis, FT-IR, (1)HNMR, UV-Vis spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), fluorescence emission, scanning electron microscopy (SEM) and viscosities and thermodynamic parameters measurements of their dilute solutions. The studies supported formation of the monomer and polymers and on the basis of these studies their structures have been assigned. The synthesized polymers were tested for their antibacterial and antifungal activities.

Identification of corrosion and damage mechanisms by using scanning electron microscopy and energy-dispersive X-ray microanalysis: contribution to failure analysis case histories

NASA Astrophysics Data System (ADS)

Pantazopoulos, G.; Vazdirvanidis, A.

2014-03-01

Emphasis is placed on the evaluation of corrosion failures of copper and machineable brass alloys during service. Typical corrosion failures of the presented case histories mainly focussed on stress corrosion cracking and dezincification that acted as the major degradation mechanisms in components used in piping and water supply systems. SEM assessment, coupled with EDS spectroscopy, revealed the main cracking modes together with the root-source(s) that are responsible for the damage initiation and evolution. In addition, fracture surface observations contributed to the identification of the incurred fracture mechanisms and potential environmental issues that stimulated crack initiation and propagation. Very frequently, the detection of chlorides among the corrosion products served as a suggestive evidence of the influence of working environment on passive layer destabilisation and metal dissolution.

Process modifications for improved carbon fiber composites: Alleviation of the electrical hazards problem

NASA Technical Reports Server (NTRS)

Ramohalli, K.

1980-01-01

Attempts to alleviate carbon-fiber-composite electrical hazards during airplane crash fires through fiber gasification are described. Thermogravimetric and differential scanning calorimetric experiments found several catalysts that caused fibers to combust when composites were exposed to test fires. Composites were tested in the 'Burn-Bang' apparatus and in high voltage electrical detection grid apparatus. In a standard three minute burn test modified composites released no fibers, while state-of-the-art composites released several hundred fiber fragments. Expected service life with and without catalytic modification was studied and electron microscopy and X-ray microanalysis furnished physical appearance and chemical composition data. An acrylic acid polymer fiber coating was developed that wet the carbon fiber surface uniformly with the catalyst, providing a marked contrast with the uneven coats obtained by solution-dipping.

Ceramic debris in hip prosthesis: correlation between synovial fluid and joint capsule.

PubMed

De Pasquale, Dalila; Stea, Susanna; Beraudi, Alina; Montesi, Monica; Squarzoni, Stefano; Toni, Aldo

2013-05-01

Detection of ceramic particles in synovial fluids allows early diagnosis of ceramic damage, but there is no evidence of a relationship between ceramic debris in the articular space and in the joint capsule. The aim of the present study is to verify if the particles isolated in the synovial fluid are comparable with those stored in the capsular tissue. Twenty-one patients were enrolled. Both synovial fluid and capsular samples were collected during revision surgery and ceramic particles were isolated and analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis. It resulted a significant correlation between the samples couples (18 out of 21). This study confirms that the synovial fluid analysis can give a clear definition of the presence of particles in the joint capsule. Copyright © 2013 Elsevier Inc. All rights reserved.

Microstructure of In x Ga1-x N nanorods grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Webster, R. F.; Soundararajah, Q. Y.; Griffiths, I. J.; Cherns, D.; Novikov, S. V.; Foxon, C. T.

2015-11-01

Transmission electron microscopy is used to examine the structure and composition of In x Ga1-x N nanorods grown by plasma-assisted molecular beam epitaxy. The results confirm a core-shell structure with an In-rich core and In-poor shell resulting from axial and lateral growth sectors respectively. Atomic resolution mapping by energy-dispersive x-ray microanalysis and high angle annular dark field imaging show that both the core and the shell are decomposed into Ga-rich and In-rich platelets parallel to their respective growth surfaces. It is argued that platelet formation occurs at the surfaces, through the lateral expansion of surface steps. Studies of nanorods with graded composition show that decomposition ceases for x ≥ 0.8 and the ratio of growth rates, shell:core, decreases with increasing In concentration.

Investigation of Selective Laser Melting Surface Alloyed Aluminium Metal Matrix Dispersive Reinforced Layers

NASA Astrophysics Data System (ADS)

Kamburov, V. V.; Dimitrova, R. B.; Kandeva, M. K.; Sofronov, Y. P.

2018-01-01

The aim of the paper is to investigate the improvement of mechanical properties and in particular wear resistance of laser surface alloyed dispersive reinforced thin layers produced by selective laser melting (SLM) technology. The wear resistance investigation of aluminium matrix composite layers in the conditions of dry friction surface with abrasive particles and nanoindentation tests were carried out. The process parameters (as scan speed) and their impact on the wear resistant layers have been evaluated. The alloyed layers containing metalized SiC particles were studied by Optical and Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray microanalysis (EDX). The obtained experimental results of the laser alloyed thin layers show significant development of their wear resistance and nanohardness due to the incorporated reinforced phase of electroless nickel coated SiC particles.

Virgin olive oil blended polyurethane micro/nanofibers ornamented with copper oxide nanocrystals for biomedical applications

PubMed Central

Amna, Touseef; Hassan, M Shamshi; Yang, Jieun; Khil, Myung-Seob; Song, Ki-Duk; Oh, Jae-Don; Hwang, Inho

2014-01-01

Recently, substantial interest has been generated in using electrospun biomimetic nanofibers of hybrids, particularly organic/inorganic, to engineer different tissues. The present work, for the first time, introduced a unique natural and synthetic hybrid micronanofiber wound dressing, composed of virgin olive oil/copper oxide nanocrystals and polyurethane (PU), developed via facile electrospinning. The as-spun organic/inorganic hybrid micronanofibers were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis, X-ray diffraction, electron probe microanalysis, and transmission electron microscopy. The interaction of cells with scaffold was studied by culturing NIH 3T3 fibroblasts on an as-spun hybrid micronanofibrous mat, and viability, proliferation, and growth were assessed. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay results and SEM observation showed that the hybrid micronanofibrous scaffold was noncytotoxic to fibroblast cell culture and was found to benefit cell attachment and proliferation. Hence our results suggest the potential utilization of as-spun micronanoscaffolds for tissue engineering. Copper oxide–olive oil/PU wound dressing may exert its positive beneficial effects at every stage during wound-healing progression, and these micronanofibers may serve diverse biomedical applications, such as tissue regeneration, damaged skin treatment, wound healing applications, etc. Conclusively, the fabricated olive oil–copper oxide/PU micronanofibers combine the benefits of virgin olive oil and copper oxide, and therefore hold great promise for biomedical applications in the near future. PMID:24611006

Composition and microstructure of maiolica from the museum of ceramics in Ascoli Piceno (Italy): evidences by electron microscopy and microanalysis

NASA Astrophysics Data System (ADS)

Gulmini, M.; Scognamiglio, F.; Roselli, G.; Vaggelli, G.

2015-09-01

The present work focuses on majolica objects from the collection of the museum of ceramic in Ascoli Piceno (Italy). The scientific investigation was performed on fragments detached from seven maiolicas attributed to the Castelli production (Abruzzi region) and one majolica from the Ascoli Piceno production (Marche region). The Castelli artifacts (late sixteenth-early eighteenth century) belong to the decorated style known as " compendiario." The piece from Ascoli Piceno recalls the decoration style of the other considered objects and is attributable to the "Paci" manufacture (first half of the nineteenth century). The selected objects were investigated by fiber optics reflectance spectroscopy, micro-X-ray fluorescence spectroscopy and scanning electron microscopy coupled with electron-dispersive X-ray spectrometry. The ceramic bodies of all objects are calcareous, whereas the glazes are lead-alkali type opacified by tin dioxide. Blue and purplish-red decorations were obtained by cobalt and manganese compounds dissolved in the glaze, respectively. Yellow and orange decorations were obtained by particles of lead antimonate and hematite. Finally, black decorations were obtained using compounds rich in manganese and iron. The study contributes to knowledge on the production of Castelli ceramics and presents first archaeometric data on the maiolica production from Ascoli Piceno. The scientific examination highlights continuity with the Renaissance production, and the joint contribution of the three analytical techniques suggests distinctive features among different productions, thus integrating and refining the information obtained by the art-historical study.

A new basaltic glass microanalytical reference material for multiple techniques

USGS Publications Warehouse

Wilson, Steve; Koenig, Alan; Lowers, Heather

2012-01-01

The U.S. Geological Survey (USGS) has been producing reference materials since the 1950s. Over 50 materials have been developed to cover bulk rock, sediment, and soils for the geological community. These materials are used globally in geochemistry, environmental, and analytical laboratories that perform bulk chemistry and/or microanalysis for instrument calibration and quality assurance testing. To answer the growing demand for higher spatial resolution and sensitivity, there is a need to create a new generation of microanalytical reference materials suitable for a variety of techniques, such as scanning electron microscopy/X-ray spectrometry (SEM/EDS), electron probe microanalysis (EPMA), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and secondary ion mass spectrometry (SIMS). As such, the microanalytical reference material (MRM) needs to be stable under the beam, be homogeneous at scales of better than 10–25 micrometers for the major to ultra-trace element level, and contain all of the analytes (elements or isotopes) of interest. Previous development of basaltic glasses intended for LA-ICP-MS has resulted in a synthetic basaltic matrix series of glasses (USGS GS-series) and a natural basalt series of glasses (BCR-1G, BHVO-2G, and NKT-1G). These materials have been useful for the LA-ICP-MS community but were not originally intended for use by the electron or ion beam community. A material developed from start to finish with intended use in multiple microanalytical instruments would be useful for inter-laboratory and inter-instrument platform comparisons. This article summarizes the experiments undertaken to produce a basalt glass reference material suitable for distribution as a multiple-technique round robin material. The goal of the analytical work presented here is to demonstrate that the elemental homogeneity of the new glass is acceptable for its use as a reference material. Because the round robin exercise is still underway, only nominal compositional ranges for each element are given in the article.

The X-ray Fluorescence Microscopy Beamline at the Australian Synchrotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paterson, D.; Jonge, M. D. de; Howard, D. L.

2011-09-09

A hard x-ray micro-nanoprobe has commenced operation at the Australian Synchrotron providing versatile x-ray fluorescence microscopy across an incident energy range from 4 to 25 keV. Two x-ray probes are used to collect {mu}-XRF and {mu}-XANES for elemental and chemical microanalysis: a Kirkpatrick-Baez mirror microprobe for micron resolution studies and a Fresnel zone plate nanoprobe capable of 60-nm resolution. Some unique aspects of the beamline design and operation are discussed. An advanced energy dispersive x-ray fluorescence detection scheme named Maia has been developed for the beamline, which enables ultrafast x-ray fluorescence microscopy.

Influence of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel welding joints

NASA Astrophysics Data System (ADS)

Zhang, Zhiqiang; Jing, Hongyang; Xu, Lianyong; Han, Yongdian; Zhao, Lei; Zhang, Jianli

2017-02-01

The influences of microstructure and elemental partitioning on pitting corrosion resistance of duplex stainless steel joints welded by gas tungsten arc welding (GTAW) and flux-cored arc welding (FCAW) with different shielding gas compositions were studied by optical microscopy, electron backscatter diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, electron probe microanalysis, and potentiostatic and potentiodynamic polarization methods The adding 2% N2 in shielding gas facilitated primary austenite formation in GTAW weld metal (WM) and suppressed Cr2N precipitation in GTAW weld root. In the HAZ, the banded microstructure disappeared while the coarse ferrite grains maintained same orientation as the banded ferrite in the BM. In the WM, the ferrite had one single orientation throughout a grain, whereas several families of austenite appeared. The austenite both in BM and WM enriched in Ni and nitro`gen, while Cr and Mo were concentrated in the ferrite and thus no element showed clear dendritic distribution in the WM (ER2209 and E2209T1). In addition, the secondary austenite had higher Ni content but lower Cr and Mo content than the primary austenite. The N2-supplemented shielding gas promoted nitrogen solid-solution in the primary and secondary austenite. Furthermore, the secondary austenite had relatively lower pitting resistance equivalent number (PREN) than the ferrite and primary austenite, thereby resulting in its preferential corrosion. The Cr2N precipitation led to relatively poor resistance to pitting corrosion in three HAZs and pure Ar shielding GTAW weld root. The N2-supplemented shielding gas improved pitting corrosion resistance of GTAW joint by increasing PREN of secondary austenite and suppressing Cr2N precipitation. In addition, the FCAW WM had much poorer resistance to pitting corrosion than the GTAW WM due to many O-Ti-Si-Mn inclusions. In the BM, since the austenite with lower PREN compared to the ferrite, the pitting corrosion occurred at the ferrite and austenite interface or within the austenite.

Characterization of Si p-i-n diode for scanning transmission ion microanalysis of biological samples

NASA Astrophysics Data System (ADS)

Devès, G.; Matsuyama, S.; Barbotteau, Y.; Ishii, K.; Ortega, R.

2006-05-01

The performance of a silicon p-i-n diode (Hamamatsu S1223-01) for the detection of charged particles was investigated and compared with the response of a standard passivated implanted planar silicon (PIPS) detector. The photodiode was characterized by ion beam induced charge collection with a micrometer spatial resolution using proton and alpha particle beams in the 1-3MeV energy range. Results indicate that homogeneity, energy resolution, and reproducibility of detection of charged particles enable the use of the low cost silicon p-i-n device as a replacement of conventional PIPS detector during scanning transmission ion microanalysis experiments. The Si p-i-n diode detection setup was successfully applied to scanning transmission ion microscopy determination of subcellular compartments on human cancer cultured cells.

[Mechanism of renal elimination of 2 elements of group IIIA of the periodic table : aluminum and indium].

PubMed

Galle, P

1981-01-05

Aluminium and indium, two elements of group IIIA of the periodic table, are concentrated by the kidney inside lysosomes of proximal tubule cell. In these lysosomes, aluminium and indium are precipitated as non-soluble phosphate salts and these precipitates are then expelled in the tubular lumen and eliminated with the urinary flow. These data have been visualized by analytical microscopy (ion microscopy and X ray microanalysis). Local acid phosphatases are assumed to permit the concentration of aluminium and indium salts inside the lysosomes.

Potentially Reactive Forms of Silica in Volcanic Rocks Using Different Analytical Approaches

NASA Astrophysics Data System (ADS)

Esteves, Hugo; Fernandes, Isabel; Janeiro, Ana; Santos Silva, António; Pereira, Manuel; Medeiros, Sara; Nunes, João Carlos

2017-12-01

Several concrete structures show signs of deterioration resulting from internal chemical reactions, such as the alkali-silica reaction (ASR). It is well known that these swelling reactions occur in the presence of moisture, between some silica mineral phases present in the aggregates and the alkalis of the concrete, leading to the degradation of concrete structures and consequently compromising their safety. In most of the cases, rehabilitation, demolition or even rebuilding of such structures is needed and the effective costs can be very high. Volcanic rocks are commonly used as aggregates in concrete, and they are sometimes the only option due to the unavailability of other rock types. These rocks may contain different forms of silica that are deleterious to concrete, such as opal, chalcedony, cristobalite, tridymite and micro- to cryptocrystalline quartz, as well as Si-rich volcanic glass. Volcanic rocks are typically very finegrained and their constituting minerals are usually not distinguished under optical microscopy, thus leading to using complementary methods. The objective of this research is to find the more adequate analytical methods to identify silica phases that might be present in volcanic aggregates and cause ASR. The complementary methods used include X-Ray Diffraction (XRD), mineral acid digestion and Scanning Electron Microscopy with Energy Dispersive X-Ray Spectrometry (SEM/EDS), as well as Electron Probe Micro-Analysis (EPMA).

Evaluation of bioreactor-cultivated bone by magnetic resonance microscopy and FTIR microspectroscopy.

PubMed

Chesnick, Ingrid E; Avallone, Francis A; Leapman, Richard D; Landis, William J; Eidelman, Naomi; Potter, Kimberlee

2007-04-01

We present a three-dimensional mineralizing model based on a hollow fiber bioreactor (HFBR) inoculated with primary osteoblasts isolated from embryonic chick calvaria. Using non-invasive magnetic resonance microscopy (MRM), the growth and development of the mineralized tissue around the individual fibers were monitored over a period of 9 weeks. Spatial maps of the water proton MRM properties of the intact tissue, with 78 microm resolution, were used to determine changes in tissue composition with development. Unique changes in the mineral and collagen content of the tissue were detected with high specificity by proton density (PD) and magnetization transfer ratio (MTR) maps, respectively. At the end of the growth period, the presence of a bone-like tissue was verified by histology and the formation of poorly crystalline apatite was verified by selected area electron diffraction and electron probe X-ray microanalysis. FTIR microspectroscopy confirmed the heterogeneous nature of the bone-like tissue formed. FTIR-derived phosphate maps confirmed that those locations with the lowest PD values contained the most mineral, and FTIR-derived collagen maps confirmed that bright pixels on MTR maps corresponded to regions of high collagen content. In conclusion, the spatial mapping of tissue constituents by FTIR microspectroscopy corroborated the findings of non-invasive MRM measurements and supported the role of MRM in monitoring the bone formation process in vitro.

Evaluation of Bioreactor-Cultivated Bone by Magnetic Resonance Microscopy and FTIR Microspectroscopy

PubMed Central

Chesnick, Ingrid E.; Avallone, Frank; Leapman, Richard D.; Landis, William J.; Eidelman, Naomi; Potter, Kimberlee

2007-01-01

We present a three-dimensional mineralizing model based on a hollow fiber bioreactor (HFBR) inoculated with primary osteoblasts isolated from embryonic chick calvaria. Using non-invasive magnetic resonance microscopy (MRM), the growth and development of the mineralized tissue around the individual fibers were monitored over a period of nine weeks. Spatial maps of the water proton MRM properties of the intact tissue, with 78 μm resolution, were used to determine changes in tissue composition with development. Unique changes in the mineral and collagen content of the tissue were detected with high specificity by proton density (PD) and magnetization transfer ratio (MTR) maps, respectively. At the end of the growth period, the presence of a bone-like tissue was verified by histology and the formation of poorly crystalline apatite was verified by selected area electron diffraction and electron probe X-ray microanalysis. FTIR microspectroscopy confirmed the heterogeneous nature of the bone-like tissue formed. FTIR-derived phosphate maps confirmed that those locations with the lowest PD values contained the most mineral, and FTIR-derived collagen maps confirmed that bright pixels on MTR maps corresponded to regions of high collagen content. In conclusion, the spatial mapping of tissue constituents by FTIR microspectroscopy corroborated the findings of non-invasive MRM measurements and supported the role of MRM in monitoring the bone formation process in vitro. PMID:17174620

Case Report: Analytical Electron Microscopy of Lung Granulomas Associated with Exposure to Coating Materials Carried by Glass Wool Fibers

PubMed Central

Ferreira, Angela S.; Moreira, Valéria B.; Castro, Marcos César S.; Soares, Porfírio J.; Algranti, Eduardo; Andrade, Leonardo R.

2010-01-01

Context Man-made vitreous fibers (MMVFs) are noncrystalline inorganic fibrous material used for thermal and acoustical insulation (e.g., rock wool, glass wool, glass microfibers, and refractory ceramic fibers). Neither epidemiologic studies of human exposure nor animal studies have shown a noticeable hazardous effect of glass wools on health. However, MMVFs have been anecdotally associated with granulomatous lung disease in several case reports. Case presentation Here, we describe the case of a patient with multiple bilateral nodular opacities who was exposed to glass wool fibers and coating materials for 7 years. Bronchoalveolar lavage fluid revealed an increased total cell count (predominantly macrophages) with numerous cytoplasmic particles. Lung biopsy showed peribronchiolar infiltration of lymphoid cells and many foreign-body–type granulomas. Alveolar macrophages had numerous round and elongated platelike particles inside the cytoplasm. X-ray microanalysis of these particles detected mainly oxygen/aluminum/silicon and oxygen/magnesium/silicon, compatible with kaolinite and talc, respectively. No elemental evidence for glass fibers was found in lung biopsy. Discussion The contribution of analytical electron microscopy applied in the lung biopsy was imperative to confirm the diagnosis of pneumoconiosis associated with a complex occupational exposure that included both MMVFs and coating materials. Relevance to clinical or professional practice This case study points out the possible participation of other components (coating materials), beyond MMVFs, in the etiology of pneumoconiosis. PMID:20123612

Definition of the Spatial Resolution of X-Ray Microanalysis in Thin Foils

NASA Technical Reports Server (NTRS)

Williams, D. B.; Michael, J. R.; Goldstein, J. I.; Romig, A. D., Jr.

1992-01-01

The spatial resolution of X-ray microanalysis in thin foils is defined in terms of the incident electron beam diameter and the average beam broadening. The beam diameter is defined as the full width tenth maximum of a Gaussian intensity distribution. The spatial resolution is calculated by a convolution of the beam diameter and the average beam broadening. This definition of the spatial resolution can be related simply to experimental measurements of composition profiles across interphase interfaces. Monte Carlo calculations using a high-speed parallel supercomputer show good agreement with this definition of the spatial resolution and calculations based on this definition. The agreement is good over a range of specimen thicknesses and atomic number, but is poor when excessive beam tailing distorts the assumed Gaussian electron intensity distributions. Beam tailing occurs in low-Z materials because of fast secondary electrons and in high-Z materials because of plural scattering.

Electron backscatter diffraction applied to lithium sheets prepared by broad ion beam milling.

PubMed

Brodusch, Nicolas; Zaghib, Karim; Gauvin, Raynald

2015-01-01

Due to its very low hardness and atomic number, pure lithium cannot be prepared by conventional methods prior to scanning electron microscopy analysis. Here, we report on the characterization of pure lithium metallic sheets used as base electrodes in the lithium-ion battery technology using electron backscatter diffraction (EBSD) and X-ray microanalysis using energy dispersive spectroscopy (EDS) after the sheet surface was polished by broad argon ion milling (IM). No grinding and polishing were necessary to achieve the sufficiently damage free necessary for surface analysis. Based on EDS results the impurities could be characterized and EBSD revealed the microsctructure and microtexture of this material with accuracy. The beam damage and oxidation/hydration resulting from the intensive use of IM and the transfer of the sample into the microscope chamber was estimated to be <50 nm. Despite the fact that the IM process generates an increase of temperature at the specimen surface, it was assumed that the milling parameters were sufficient to minimize the heating effect on the surface temperature. However, a cryo-stage should be used if available during milling to guaranty a heating artefact free surface after the milling process. © 2014 Wiley Periodicals, Inc.

Thermoelectric properties and thermal stability of Bi-doped PbTe single crystal

NASA Astrophysics Data System (ADS)

Chen, Zhong; Li, Decong; Deng, Shuping; Tang, Yu; Sun, Luqi; Liu, Wenting; Shen, Lanxian; Yang, Peizhi; Deng, Shukang

2018-06-01

In this study, n-type Bi-doped single-crystal PbTe thermoelectric materials were prepared by melting and slow cooling method according to the stoichiometric ratio of Pb:Bi:Te = 1-x:x:1 (x = 0, 0.1, 0.15, 0.2, 0.25). The X-ray diffraction patterns of Pb1-xBixTe samples show that all main diffraction peaks are well matched with the PbTe matrix, which has a face-centered cubic structure with the space group Fm 3 bar m . Electron probe microanalysis reveals that Pb content decreases gradually, and Te content remains invariant basically with the increase of Bi content, indicating that Bi atoms are more likely to replace Pb atoms. Thermal analysis shows that the prepared samples possess relatively high thermal stability. Simultaneously, transmission electron microscopy and selected area electron diffraction pattern indicate that the prepared samples have typical single-crystal structures with good mechanical properties. Moreover, the electrical conductivity of the prepared samples improved significantly compared with that of the pure sample, and the maximum ZT value of 0.84 was obtained at 600 K by the sample with x = 0.2.

Recycling-oriented characterization of plastic frames and printed circuit boards from mobile phones by electronic and chemical imaging.

PubMed

Palmieri, Roberta; Bonifazi, Giuseppe; Serranti, Silvia

2014-11-01

This study characterizes the composition of plastic frames and printed circuit boards from end-of-life mobile phones. This knowledge may help define an optimal processing strategy for using these items as potential raw materials. Correct handling of such a waste is essential for its further "sustainable" recovery, especially to maximize the extraction of base, rare and precious metals, minimizing the environmental impact of the entire process chain. A combination of electronic and chemical imaging techniques was thus examined, applied and critically evaluated in order to optimize the processing, through the identification and the topological assessment of the materials of interest and their quantitative distribution. To reach this goal, end-of-life mobile phone derived wastes have been systematically characterized adopting both "traditional" (e.g. scanning electronic microscopy combined with microanalysis and Raman spectroscopy) and innovative (e.g. hyperspectral imaging in short wave infrared field) techniques, with reference to frames and printed circuit boards. Results showed as the combination of both the approaches (i.e. traditional and classical) could dramatically improve recycling strategies set up, as well as final products recovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

New insights on the Dronino iron meteorite by double-pulse micro-Laser-Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Tempesta, Gioacchino; Senesi, Giorgio S.; Manzari, Paola; Agrosì, Giovanna

2018-06-01

Two fragments of an iron meteorite shower named Dronino were characterized by a novel technique, i.e. Double-Pulse micro-Laser Induced Breakdown Spectroscopy (DP-μLIBS) combined with optical microscope. This technique allowed to perform a fast and detailed analysis of the chemical composition of the fragments and permitted to determine their composition, the alteration state differences and the cooling rate of the meteorite. Qualitative analysis indicated the presence of Fe, Ni and Co in both fragments, whereas the elements Al, Ca, Mg, Si and, for the first time Li, were detected only in one fragment and were related to its post-falling alteration and contamination by weathering processes. Quantitative analysis data obtained using the calibration-free (CF) - LIBS method showed a good agreement with those obtained by traditional methods generally applied to meteorite analysis, i.e. Electron Dispersion Spectroscopy - Scanning Electron Microscopy (EDS-SEM), also performed in this study, and Electron Probe Microanalysis (EMPA) (literature data). The local and coupled variability of Ni and Co (increase of Ni and decrease of Co) determined for the unaltered portions exhibiting plessite texture, suggested the occurrence of solid state diffusion processes under a slow cooling rate for the Dronino meteorite.

Structural similarities between hematoidin crystals and asteroid bodies: evidence of lipid composition.

PubMed

Brenner, D S; Drachenberg, C B; Papadimitriou, J C

2001-02-01

Hematoidin crystals (HC) are found in tissues where extravasated erythrocytes undergo degradation. Previous studies have determined that hematoidin is composed, in part, of a bilirubin-like pigment. In a previous study (Papadimitriou and Drachenberg, Ultrastruct. Pathol. 16, 413-421, 1992), we demonstrated that giant cell asteroid bodies (AB) are formed by membrane lipid bilayers. We evaluated three cases in which HC developed within splenic infarcts. The crystals were analyzed by light microscopy (LM), electron microscopy (EM), and X-ray microanalysis. A case of sarcoidosis with multiple epithelioid granulomas containing AB was studied for comparison. By LM the HC demonstrated intense, golden-color, fine threads, both intracellularly and extracellularly, in small and large clusters, and in radiating, star-shape patterns ranging in size from 2 to 200 microm. By EM the HC were composed of a core of empty clefts, consistent with dissolved lipids, suggestive of cholesterol crystals, and were surrounded by myelinoid membrane aggregates. The AB showed by LM significant morphological similarities with the intracellular HC. By EM, the AB were composed of a core of dense phospholipid bilayer tubes surrounded by a halo of myelinoid membranes. No accumulation of specific elements was found in either HC or AB by X-ray microanalysis. HC and AB show a similar star-shape morphology by both LM and EM. We postulate that this shape is due to the physicochemical properties of the accumulated lipids which originate from superfluous cell membranes created during cell fusion in the case of AB and after cellular (predominantly red cell) breakdown in the case of HC. The golden color of the HC likely results from adsorption of hydrophobic bilirubin-like pigments left over from erythrocyte breakdown into the accumulated lipids. Thus, this study shows two different (patho)physiological processes that lead to a markedly similar morphological end-product and provides further support to our proposed mechanism for AB formation.

Fabrication of luminescent SrWO{sub 4} thin films by a novel electrochemical method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen Lianping; Gao Yuanhong

2007-10-02

Highly crystallized SrWO{sub 4} thin films with single scheelite structure were prepared within 60 min by a cell electrochemical method. X-ray diffraction analysis shows that SrWO{sub 4} thin films have a tetragonal structure. Scanning electron microscopy examinations reveal that SrWO{sub 4} grains grow well in tetragonal tapers and grains like flowers or bunches, which can usually form by using the electrolysis electrochemical method, have disappeared under cell electrochemical conditions. X-ray photoelectron spectra and energy dispersive X-ray microanalysis examinations demonstrate that the composition of the film is consistent with its stoichiometry. These SrWO{sub 4} films show a single blue emission peakmore » (located at 460 nm) using an excitation wave of 230 nm. The speed of cell electrochemical method can be controlled by changing temperature. The optimum treatment temperature is about 50-60 deg. C.« less

Cyanobacterial mats: Microanalysis of community metabolism

NASA Technical Reports Server (NTRS)

Cohen, Y.; Bermudes, D.; Fischer, U.; Haddad, R.; Prufert, L.; Scheulderman-Suylen, T.; Shaw, T.

1985-01-01

The microbial communities in two sites were studied using several approaches: (1) light microscopy; (2) the measurement of microprofiles of oxygen and sulfide at the surface of the microbial mat; (3) the study of diurnal variation of oxygen and sulfides; (4) in situ measurement of photosynthesis and sulfate reduction and study of the coupling of these two processes; (5) measurement of glutathione in the upper layers of the microbial mat as a possible oxygen quencher; (6) measurement of reduced iron as a possible intermediate electron donor along the established redoxcline in the mats; (7) measurement of dissolved phosphate as an indicator of processes of break down of organic matter in these systems; and (8) measurement of carbon dioxide in the interstitial water and its delta C-13 in an attempt to understand the flow of CO2 through the systems. Microbial processes of primary production and initial degradation at the most active zone of the microbial mat were analyzed.

The Effect of Multiple Surface Treatments on Biological Properties of Ti-6Al-4V Alloy

NASA Astrophysics Data System (ADS)

Parsikia, Farhang; Amini, Pupak; Asgari, Sirous

2014-09-01

In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface conditions. Based on the data obtained in this study, low-energy laser processing generally yields a better biological response. The maximum bioactivity was attained in those samples exposed to a three step treatment including low-energy laser treatment followed by grit blasting and anodizing.

Surface characterization of ZnO/ZnMn2O4 and Cu/Mn3O4 powders obtained by thermal degradation of heterobimetallic complexes

NASA Astrophysics Data System (ADS)

Barrault, Joël; Makhankova, Valeriya G.; Khavryuchenko, Oleksiy V.; Kokozay, Vladimir N.; Ayrault, Philippe

2012-03-01

From the selective transformation of the heterometallic (Zn-Mn or Cu-Mn) carboxylate complexes with 2,2'-bipyridyl by thermal degradation at relatively low (350 °C) temperature, it was possible to get either well defined spinel ZnMn2O4 over zinc oxide or well dispersed copper particles surrounded by a manganese oxide (Mn3O4) in a core-shell like structure. Morphology of the powder surface was examined by scanning electron microscopy with energy dispersive X-ray microanalysis (SEM/EDX). Surface composition was determined by X-ray photoelectron spectroscopy (XPS). Specific surface of the powders by nitrogen adsorption was found to be 33±0.2 and 9±0.06 m2 g-1 for Zn-Mn and Cu-Mn samples, respectively, which is comparable to those of commercial products.

IDM release behavior and surface characteristics of the novel Cu/IDM/LDPE nanocomposite for intrauterine device.

PubMed

Yang, Zhihong; Xie, Changsheng; Xiang, Hua; Feng, Jinqing; Xia, Xianping; Cai, Shuizhou

2009-03-01

Copper/indomethacin/low-density polyethylene (Cu/IDM/LDPE) nanocomposite was prepared as a novel material for intra-uterine device (IUD). IDM release profile of the nanocomposite was investigated by using spectrophotometer. The results show that IDM release rate of Cu/IDM/LDPE nanocomposite is higher in simulated uterine solution than that in methanol, confirming that the release process of IDM is dominated mainly by pore diffusion. The decrease in copper particle size and the increase in copper mass content all accelerate IDM release, indicating that IDM release rate can be adjusted by changing copper loading or copper particle size. The surface of the incubated nanocomposite was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray microanalysis. A few deposits composed of P, Cl, Ca, Cu and O were observed on the nanocomposite surface, which may be related to the presence of IDM particles with large particle size.

Effect of nitric acid treatment on activated carbon derived from oil palm shell

NASA Astrophysics Data System (ADS)

Allwar, Allwar; Hartati, Retno; Fatimah, Is

2017-03-01

The primary object of this work is to study the effect of nitric acid on the porous and morphology structure of activated carbon. Production of activated carbon from oil palm shell was prepared with pyrolysis process at temperature 900°C and by introduction of 10 M nitric acid. Determination of surface area, pore volume and pore size distribution of activated carbon was conducted by the N2 adsorption-desorption isotherm at 77 K. Morphology structure and elemental micro-analysis of activated carbon were estimated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray (EDX), respectively. The result shows that activated carbon after treating with nitric acid proved an increasing porous characteristics involving surface area, pore volume and pore size distribution. It also could remove the contaminants including metals and exhibit an increasing of pores and crevices all over the surface.

Oxalate production by wood-rotting fungi growing in toxic metal-amended medium.

PubMed

Jarosz-Wilkolazka, Anna; Gadd, Geoffrey M

2003-07-01

In this report, we have identified oxalic acid as an important metabolite elaborated in the response of wood-rotting fungi to toxic metal stress. The formation of oxalate crystals by white rot fungi (Bjerkandera fumosa, Phlebia radiata and Trametes versicolor) and the brown rot fungus Fomitopsis pinicola, grown on media containing high levels of toxic metal ions has been visualized using scanning electron microscopy (SEM) with energy-dispersive X-ray micro-analysis (EDXA) and HPLC. There were no significant differences between the growth of controls (metal-free) and on the 0.5% CaCO(3), Co(3)(PO(4))(2) or Zn(3)(PO(4))(2)-amended plates. ZnO inhibited the growth of all strains. Crystals were not detected in Zn(3)(PO(4))(2)-amended plates. The four examined strains displayed the formation of crystals on ZnO, Co(3)(PO(4))(2) and CaCO(3)-amended plates.

Modification of carbon composites by nanoceramic compounds

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzebski, W.; Długoń, E.; Stoch, G. J.; Błażewicz, S.; Adamczyk, A.; Tatarzyńska, K.

2005-06-01

Carbon-carbon composites (C/C) exhibit excellent high-temperature mechanical properties but their air oxidation limits their use at temperatures above 500 °C to inert atmosphere. Variety of coatings has been used to protect C/C composites from oxidation. In this work C/C composite substrates were covered with ceramic multilayer coats by electrophoretic deposition from ceramic sols such as silica sol, alumina sol and silica-lumina sol. Sol particles were of nano-sized dimensions. Deposited coats were annealed at 900-1500 °C. Oxidation tests at 600 °C reveal that the best protection of C/C composite against oxidation gives the multilayer coat formed by three or four electrophoretic depositions. The phase composition in the final annealed layers was analyzed by Infrared spectroscopy (FTIR) and by X-ray diffraction analysis (XRD). Morphology and chemical composition was observed using Scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis (EDS).

Microstructural Changes Due to Alkali-Silica Reaction during Standard Mortar Test

PubMed Central

Shin, Jun-Ho; Struble, Leslie J.; Kirkpatrick, R. James

2015-01-01

The microstructural development of mortar bars with silica glass aggregate undergoing alkali-silica reaction (ASR) under the conditions of American Society for Testing and Materials (ASTM) Standard Test C1260 was analyzed using scanning electron microscopy and qualitative X-ray microanalysis. Cracking in the aggregate, the hydrated paste, and the paste-aggregate interface was important in the development of the microstructure. Cracks were characterized according to their location, their relationship to other cracks, and whether they are filled with ASR gel. Expansion of the bars was approximately 1% at 12 days and 2% at 53 days. They fell apart by 63 days. The bars contained two zones, an inner region that was undergoing ASR and an outer and much more highly damaged zone that extended further inward over time. Evidence of ASR was present even during the period when specimens were immersed in water, prior to immersion in NaOH solution. PMID:28793711

Identification of Nanocrystalline Inclusions in Bismuth-Doped Silica Fibers and Preforms.

PubMed

Iskhakova, Liudmila D; Milovich, Filipp O; Mashinsky, Valery M; Zlenko, Alexander S; Borisovsky, Sergey E; Dianov, Evgeny M

2016-10-01

The nature of nanocrystalline inclusions and dopant distribution in bismuth-doped silicate fibers and preforms are studied by scanning and transmission electron microscopy, and energy and wavelength-dispersive X-ray microanalysis. The core compositions are Bi:SiO2, Bi:Al2O3-SiO2, Bi:GeO2-SiO2, Bi:Al2O3-GeO2-SiO2, and Bi:P2O5-Al2O3-GeO2-SiO2. Nanocrystals of metallic Bi, Bi2O3, SiO2, GeO2, and Bi4(GeO4)3 are observed in these glasses. These inclusions can be the reason for the background optical loss in bismuth-doped optical fibers. The bismuth concentration of 0.0048±0.0006 at% is directly measured in aluminosilicate optical fibers with effective laser generation (slope efficiency of 27% at room temperature).

Silica Deposition on the Leaves of Mir- and Earth-Grown Super Dwarf Wheat

NASA Technical Reports Server (NTRS)

Campbell, William F.; Bubenheim, David L.; Salisbury, Frank B.; Bingham, Gail E.; McManus, William R.; Biesinger, H. D.; Strickland, D. T.; Levinskikh, Maragarita; Sytchev, Vladimir N.; Podolsky, Igor

2000-01-01

Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) microanalysis were used to investigate the nature of crystals deposited on leaves of Mir- and Earth-grown Super Dwarf wheat (Triticum aestivum L.) plants. Leaves from these plants exhibited dense and uniformly distributed crystals on leaf abaxial surfaces when viewed by SEM. Young leaves showed that crystals initially accumulated around the stomata on the adaxial surface, but became more dense and uniformly distributed as the leaves aged. EDX microanalyses of the Balkanine (a nutrient charged clinoptilolite zeolite) medium in which the wheat plants were grown showed an elemental pattern similar to that observed on the wheat leaves. The absence of N and P in the Balkanine suggests that they were completely utilized by the plants. Only Si and O were evident in the drying agent, Sorb-it-Silica (trademark), and perhaps could have accounted for some of the Si observed on the plant tissue.

DOE Office of Scientific and Technical Information (OSTI.GOV)

John N. DuPont; Jeffrey D. Farren; Andrew W. Stockdale

It is commonly believed that high alloy steel castings have inferior corrosion resistance to their wrought counterparts as a result of the increased amount of microsegregation remaining in the as-cast structure. Homogenization and dissolution heat treatments are often utilized to reduce or eliminate the residual microsegregation and dissolve the secondary phases. Detailed electron probe microanalysis (EPMA) and light optical microscopy (LOM) were utilized to correlate the amount of homogenization and dissolution present after various thermal treatments with calculated values and with the resultant corrosion resistance of the alloys.The influence of heat treatment time and temperature on the homogenization and dissolutionmore » kinetics were investigated using stainless steel alloys CN3MN and CK3MCuN. The influence of heat treatment time and temperature on the impact toughness and corrosion reistance of cast stainless steel alloys CF-3, CF-3M, CF-8, and CF-8M was also investigated.« less

Microstructural Changes Due to Alkali-Silica Reaction during Standard Mortar Test

DOE PAGES

Shin, Jun-Ho; Struble, Leslie; Kirkpatrick, R.

2015-12-01

The microstructural development of mortar bars with silica glass aggregate undergoing alkali-silica reaction (ASR) under the conditions of American Society for Testing and Materials (ASTM) Standard Test C1260 was analyzed using scanning electron microscopy and qualitative X-ray microanalysis. Cracking in the aggregate, the hydrated paste, and the paste-aggregate interface was important in the development of the microstructure. Cracks were characterized according to their location, their relationship to other cracks, and whether they are filled with ASR gel. Expansion of the bars was approximately 1% at 12 days and 2% at 53 days. They fell apart by 63 days. The barsmore » contained two zones, an inner region that was undergoing ASR and an outer and much more highly damaged zone that extended further inward over time. Evidence of ASR was present even during the period when specimens were immersed in water, prior to immersion in NaOH solution.« less

Microstructural Changes Due to Alkali-Silica Reaction during Standard Mortar Test.

PubMed

Shin, Jun-Ho; Struble, Leslie J; Kirkpatrick, R James

2015-12-02

The microstructural development of mortar bars with silica glass aggregate undergoing alkali-silica reaction (ASR) under the conditions of American Society for Testing and Materials (ASTM) Standard Test C1260 was analyzed using scanning electron microscopy and qualitative X-ray microanalysis. Cracking in the aggregate, the hydrated paste, and the paste-aggregate interface was important in the development of the microstructure. Cracks were characterized according to their location, their relationship to other cracks, and whether they are filled with ASR gel. Expansion of the bars was approximately 1% at 12 days and 2% at 53 days. They fell apart by 63 days. The bars contained two zones, an inner region that was undergoing ASR and an outer and much more highly damaged zone that extended further inward over time. Evidence of ASR was present even during the period when specimens were immersed in water, prior to immersion in NaOH solution.

Chemometric classification of gunshot residues based on energy dispersive X-ray microanalysis and inductively coupled plasma analysis with mass-spectrometric detection

NASA Astrophysics Data System (ADS)

Steffen, S.; Otto, M.; Niewoehner, L.; Barth, M.; Bro¿żek-Mucha, Z.; Biegstraaten, J.; Horváth, R.

2007-09-01

A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: 'gunshot residue characteristic', 'consistent with gunshot residue' and environmental particles, respectively. Potential gunshot residue particles are manually checked and - if necessary - confirmed by the operating forensic scientist. As there are continuing developments on the ammunition market worldwide, it becomes more and more difficult to assign a detected particle to a particular ammunition brand. As well, the differentiation towards environmental particles similar to gunshot residue is getting more complex. To keep external conditions unchanged, gunshot residue particles were collected using a specially designed shooting device for the test shots revealing defined shooting distances between the weapon's muzzle and the target. The data obtained as X-ray spectra of a number of particles (3000 per ammunition brand) were reduced by Fast Fourier Transformation and subjected to a chemometric evaluation by means of regularized discriminant analysis. In addition to the scanning electron microscopy in combination with energy dispersive X-ray microanalysis results, isotope ratio measurements based on inductively coupled plasma analysis with mass-spectrometric detection were carried out to provide a supplementary feature for an even lower risk of misclassification.

Photovoltaic devices based on quantum dot functionalized nanowire arrays embedded in an organic matrix

NASA Astrophysics Data System (ADS)

Kung, Patrick; Harris, Nicholas; Shen, Gang; Wilbert, David S.; Baughman, William; Balci, Soner; Dawahre, Nabil; Butler, Lee; Rivera, Elmer; Nikles, David; Kim, Seongsin M.

2012-01-01

Quantum dot (QD) functionalized nanowire arrays are attractive structures for low cost high efficiency solar cells. QDs have the potential for higher quantum efficiency, increased stability and lifetime compared to traditional dyes, as well as the potential for multiple electron generation per photon. Nanowire array scaffolds constitute efficient, low resistance electron transport pathways which minimize the hopping mechanism in the charge transport process of quantum dot solar cells. However, the use of liquid electrolytes as a hole transport medium within such scaffold device structures have led to significant degradation of the QDs. In this work, we first present the synthesis uniform single crystalline ZnO nanowire arrays and their functionalization with InP/ZnS core-shell quantum dots. The structures are characterized using electron microscopy, optical absorption, photoluminescence and Raman spectroscopy. Complementing photoluminescence, transmission electron microanalysis is used to reveal the successful QD attachment process and the atomistic interface between the ZnO and the QD. Energy dispersive spectroscopy reveals the co-localized presence of indium, phosphorus, and sulphur, suggestive of the core-shell nature of the QDs. The functionalized nanowire arrays are subsequently embedded in a poly-3(hexylthiophene) hole transport matrix with a high degree of polymer infiltration to complete the device structure prior to measurement.

An ultrastructural and immunogold localization study of proteoglycans associated with the osteocytes of fetal bone in osteogenesis imperfecta.

PubMed

Sarathchandra, P; Pope, F M; Ali, S Y

1996-06-01

Osteogenesis imperfecta (OI) is a rare, heterogeneous, inherited connective tissue disorder frequently caused by abnormalities of type I collagen. It is characterized by bone fragility, osteopenia, and progressive skeletal deformities. Electron microscopy of three OI type II fetal bone samples revealed numerous large osteocyte lacunae. In addition, there was a perilacunar osteoid-like band of collagen surrounding the osteocytes, which was unmineralized and morphologically unusual. Furthermore, large osteocyte lacunae contained fine particles and filamentous material similar to the expected ultrastructural appearance of proteoglycans. More detailed examination was carried out using histochemical and immunogold localization of proteoglycans at light and ultrastructural levels. These tests and the use of electron probe X-ray microanalysis confirmed that the material in the osteocyte lacunae was proteoglycan. In contrast, in the age- and site-matched normal fetal bone, all the osteocyte lacunae appeared negative for proteoglycan. Proteoglycans are regarded as inhibitors of calcification. Our observation of substantial amounts of proteoglycan in abnormally enlarged osteocytic lacunae of some OI fetal bone suggests association with the abnormal bone of this particular subtype of OI type II.

Effects of sol-gel processing parameters on the phases and microstructures of HA films.

PubMed

Wang, Diangang; Chen, Chuanzhong; Liu, Xiuna; Lei, Tingquan

2007-06-15

Bioactive hydroxyapatite (HA) films were fabricated by a sol-gel method and triethylphosphate and calcium nitrate were used as the phosphorus and calcium precursors, respectively. The effects of the heat treatment temperature, pH level and substrate materials on the phases and microstructures of HA films were studied by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and electronic probe microanalysis (EPMA) and so on. The results show that all the sol-gel films are composed of the phases of HA, CaO, TiO(2) and CaTiO(3). With increasing the calcining temperature, the crystallinity of the films increases, the structure becomes more compact and changes from granular and lamellar to cellular structure, and the Ca/P ratio increases slightly because of the loss of P in the films. The addition of ammonia (adjusting the pH level to be about 7.5) can increase the HA content in the films, and the difference of substrate materials only has a little influence on the microstructure of the sol-gel films.

Spin and valence dependence of iron partitioning in Earth’s deep mantle

PubMed Central

Piet, Hélène; Badro, James; Nabiei, Farhang; Dennenwaldt, Teresa; Shim, Sang-Heon; Cantoni, Marco; Hébert, Cécile; Gillet, Philippe

2016-01-01

We performed laser-heated diamond anvil cell experiments combined with state-of-the-art electron microanalysis (focused ion beam and aberration-corrected transmission electron microscopy) to study the distribution and valence of iron in Earth’s lower mantle as a function of depth and composition. Our data reconcile the apparently discrepant existing dataset, by clarifying the effects of spin (high/low) and valence (ferrous/ferric) states on iron partitioning in the deep mantle. In aluminum-bearing compositions relevant to Earth’s mantle, iron concentration in silicates drops above 70 GPa before increasing up to 110 GPa with a minimum at 85 GPa; it then dramatically drops in the postperovskite stability field above 116 GPa. This compositional variation should strengthen the lowermost mantle between 1,800 km depth and 2,000 km depth, and weaken it between 2,000 km depth and the D” layer. The succession of layers could dynamically decouple the mantle above 2,000 km from the lowermost mantle, and provide a rheological basis for the stabilization and nonentrainment of large low-shear-velocity provinces below that depth. PMID:27647917

Nano-chemo-mechanical signature of conventional oil-well cement systems: Effects of elevated temperature and curing time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krakowiak, Konrad J., E-mail: kjkrak@mit.edu; Thomas, Jeffrey J., E-mail: JThomas39@slb.com; Musso, Simone, E-mail: SMusso@slb.com

2015-01-15

With ever more challenging (T,p) environments for cementing applications in oil and gas wells, there is a need to identify the fundamental mechanisms of fracture resistant oil well cements. We report results from a multi-technique investigation of behavior and properties of API class G cement and silica-enriched cement systems subjected to hydrothermal curing from 30 °C to 200 °C; including electron probe microanalysis, X-ray diffraction, thermogravimetry analysis, electron microscopy, neutron scattering (SANS), and fracture scratch testing. The results provide a new insight into the link between system chemistry, micro-texture and micro-fracture toughness. We suggest that the strong correlation found betweenmore » chemically modulated specific surface and fracture resistance can explain the drop in fracture properties of neat oil-well cements at elevated temperatures; the fracture property enhancement in silica-rich cement systems, between 110° and 175 °C; and the drop in fracture properties of such systems through prolonged curing over 1 year at 200 °C.« less

Diffusion bonding of titanium to 304 stainless steel

NASA Astrophysics Data System (ADS)

Ghosh, M.; Bhanumurthy, K.; Kale, G. B.; Krishnan, J.; Chatterjee, S.

2003-11-01

Diffusion bonding between commercially pure titanium and an austenitic stainless steel (AISI 304) has been carried out in the temperature range of 850-950 °C for 2 h at uniaxial pressure of 3 MPa in vacuum. The microstructure of the diffusion zone has been analysed by optical and scanning electron microscopy (SEM). The interdiffusion of the diffusing species across the interface has been evaluated by electron probe microanalysis (EPMA). The reaction products formed at the interface have been identified by X-ray diffraction technique. It has been observed that the diffusion zone is dominated by the presence of the σ phase close to the stainless steel side and the solid solution of β-Ti (solutes are Fe, Cr and Ni) close to the titanium. The presence of Fe 2Ti and FeTi has been found in the reaction zone. It has been observed that the bond strength (˜222 MPa) is highest for the couple processed at 850 °C and this value decreases with rise in joining temperature. The variation of strength of the transition joints is co-related with the microstructural characteristics of the diffusion zone.

Evaluation of enamel by scanning electron microscopy green LED associated to hydrogen peroxide 35% for dental bleaching

NASA Astrophysics Data System (ADS)

Monteiro, Juliana S. C.; de Oliveira, Susana C. P. S.; Zanin, Fátima A. A.; Santos, Gustavo M. P.; Sampaio, Fernando J. P.; Gomes Júnior, Rafael Araújo; Gesteira, Maria F. M.; Vannier-Santos, Marcos A.; Pinheiro, Antônio Luiz B.

2014-02-01

Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.

The electron microscope appearance of the subchondral bone plate in the human femoral head in osteoarthritis and osteoporosis

PubMed Central

LI, BAOHUA; MARSHALL, DEBORAH; ROE, MARTIN; ASPDEN, RICHARD M.

1999-01-01

The subchondral bone plate supports the articular cartilage in diarthrodial joints. It has a significant mechanical function in transmitting loads from the cartilage into the underlying cancellous bone and has been implicated in the destruction of cartilage in osteoarthritis (OA) and its sparing in osteoporosis (OP), but little is known of its composition, structure or material properties. This study investigated the microscopic appearance and mineral composition of the subchondral bone plate in femoral heads from patients with OA or OP to determine how these correspond to changes in composition and stiffness found in other studies. Freeze-fractured full-depth samples of the subchondral bone plate from the femoral heads of patients with osteoarthritis, osteoporosis or a matched control group were examined using back scattered and secondary emission scanning electron microscopy. Other samples were embedded and polished and examined using back-scattered electron microscopy and electron probe microanalysis. The appearances of the samples from the normal and osteoporotic patients were very similar, with the subchondral bone plate overlayed by a layer of calcified cartilage. Osteoporotic samples presented a more uniform fracture surface and the relative thicknesses of the layers appeared to be different. In contrast, the OA bone plate appeared to be porous and have a much more textured surface. There were occasional sites of microtrabecular bone formation between the trabeculae of the underlying cancellous bone, which were not seen in the other groups, and more numerous osteoclast resorption pits. The calcified cartilage layer was almost absent and the bone plate was apparently thickened. The appearance of the osteoarthritic subchondral bone plate was, therefore, considerably different from both the normal and the osteoporotic, strongly indicative of abnormal cellular activity. PMID:10473297

Subgrain boundary analyses in deformed orthopyroxene by TEM/STEM with EBSD-FIB sample preparation technique

NASA Astrophysics Data System (ADS)

Kogure, Toshihiro; Raimbourg, Hugues; Kumamoto, Akihito; Fujii, Eiko; Ikuhara, Yuichi

2014-12-01

High-resolution structure analyses using electron beam techniques have been performed for the investigation of subgrain boundaries (SGBs) in deformed orthopyroxene (Opx) in mylonite from Hidaka Metamorphic Belt, Hokkaido, Japan, to understand ductile deformation mechanism of silicate minerals in shear zones. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis of Opx porphyroclasts in the mylonitic rock indicated that the crystal orientation inside the Opx crystals gradually changes by rotation about the b-axis by SGBs and crystal folding. In order to observe the SGBs along the b-axis by transmission electron microscopy (TEM) or scanning TEM (STEM), the following sample preparation protocol was adopted. First, petrographic thin sections were slightly etched with hydrofluoric acid to identify SGBs in SEM. The Opx crystals whose b-axes were oriented close to the normal of the surface were identified by EBSD, and the areas containing SGBs were picked and thinned for (S) TEM analysis with a focused ion beam instrument with micro-sampling system. High-resolution TEM imaging of the SGBs in Opx revealed various boundary structures from a periodic array of dissociated (100) [001] edge dislocations to partially or completely incoherent crystals, depending on the misorientation angle. Atomic-resolution STEM imaging clearly confirmed the formation of clinopyroxene (Cpx) structure between the dissociated partial dislocations. Moreover, X-ray microanalysis in STEM revealed that the Cpx contains a considerable amount of calcium replacing iron. Such chemical inhomogeneity may limit glide motion of the dislocation and eventually the plastic deformation of the Opx porphyroclasts at a low temperature. Chemical profiles across the high-angle incoherent SGB also showed an enrichment of the latter in calcium at the boundary, suggesting that SGBs are an efficient diffusion pathway of calcium out of host Opx grain during cooling.

Antibacterial activity and interaction mechanism of electrospun zinc-doped titania nanofibers.

PubMed

Amna, Touseef; Hassan, M Shamshi; Barakat, Nasser A M; Pandeya, Dipendra Raj; Hong, Seong Tshool; Khil, Myung-Seob; Kim, Hak Yong

2012-01-01

In this study, a biological evaluation of the antimicrobial activity of Zn-doped titania nanofibers was carried out using Escherichia coli ATCC 52922 (Gram negative) and Staphylococcus aureus ATCC 29231 (Gram positive) as model organisms. The utilized Zn-doped titania nanofibers were prepared by the electrospinning of a sol-gel composed of zinc nitrate, titanium isopropoxide, and polyvinyl acetate; the obtained electrospun nanofibers were vacuum dried at 80°C and then calcined at 600°C. The physicochemical properties of the synthesized nanofibers were determined by X-ray diffraction pattern, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe microanalysis, thermogravimetry, and transmission electron microscopy (TEM). The antibacterial activity and the acting mechanism of Zn-doped titania nanofibers against bacteria were investigated by calculation of minimum inhibitory concentration and analyzing the morphology of the bacterial cells following the treatment with nanofibers solution. Our investigations reveal that the lowest concentration of Zn-doped titania nanofibers solution inhibiting the growth of S. aureus ATCC 29231 and E. coli ATCC 52922 strains is found to be 0.4 and 1.6 μg/ml, respectively. Furthermore, Bio-TEM analysis demonstrated that the exposure of the selected microbial strains to the nanofibers led to disruption of the cell membranes and leakage of the cytoplasm. In conclusion, the combined results suggested doping promotes antimicrobial effect; synthesized nanofibers possess a very large surface-to-volume ratio and may damage the structure of the bacterial cell membrane, as well as depress the activity of the membranous enzymes which cause bacteria to die in due course.

The influence of A-site rare-earth for barium substitution on the chemical structure and ferroelectric properties of BZT thin films

NASA Astrophysics Data System (ADS)

Ostos, C.; Martínez-Sarrión, M. L.; Mestres, L.; Delgado, E.; Prieto, P.

2009-10-01

Rare-earth ( RE) doped Ba(Zr,Ti)O 3 (BZT) thin films were prepared by rf-magnetron sputtering from a Ba 0.90Ln0.067Zr 0.09Ti 0.91O 3 ( Ln=La, Nd) target. The films were deposited at a substrate temperature of 600 °C in a high oxygen pressure atmosphere. X-ray diffraction (XRD) patterns of RE-BZT films revealed a <001> epitaxial crystal growth on Nb-doped SrTiO 3, <001> and <011> growth on single-crystal Si, and a <111>-preferred orientation on Pt-coated Si substrates. Scanning electron microscopy (SEM) showed uniform growth of the films deposited, along with the presence of crystals of about half-micron size on the film's surface. Transmission electron microscopy (TEM) evidenced high crystalline films with thicknesses of about 100 nm for 30 min of sputtering. Electron-probe microanalysis (EPMA) corroborated the growth rate (3.0-3.5 nm/min) of films deposited on Pt-coated Si substrates. X-ray photoelectron spectroscopy (XPS), in depth profile mode, showed variations in photoelectron Ti 2 p doublet positions at lower energies with spin-orbital distances characteristic of BaTiO 3-based compounds. The XPS analysis revealed that lanthanide ions positioned onto the A-site of the BZT-perovskite structure increasing the MO 6-octahedra distortion ( M=Ti, Zr) and, thereby, modifying the Ti-O binding length. Polarization-electric field hysteresis loops on Ag/ RE-doped BZT/Pt capacitor showed good ferroelectric behavior and higher remanent polarization values than corresponding non-doped system.

Loose nanofiltration membrane for dye/salt separation through interfacial polymerization with in-situ generated TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Qi; Fan, Lin; Yang, Zhen; Zhang, Runnan; Liu, Ya-nan; He, Mingrui; Su, Yanlei; Jiang, Zhongyi

2017-07-01

In this study, a high flux nanofiltration (NF) membrane with hybrid polymer-nanoparticle active layer was fabricated by chemical crosslinking of piperazine (PIP) and 1, 3, 5-benzene tricarbonyl trichloride (TMC). An in-situ generated method was applied to deposit titanium dioxide (TiO2) nanoparticles uniformly on the membrane surface, leading to the enhancement of the surface hydrophilicity, roughness and relative surface area of the polyamide (PA) layer. The morphology of the modified membrane was investigated by scanning electron microscopy (SEM) and Atomic force microscopy (AFM), also energy dispersive X-ray microanalysis (EDX) was used to analyze the distribution of Ti element. Chemical structure was observed by Fourier transmission infrared attenuated total reflectance (FTIR-ATR) spectroscopy. Remarkably, the optimal water flux of the loose NF membrane was 65.0 Lm-2 h-1 bar-1 nearly 5 times as much as the pure PA membrane flux. The rejections of the loose NF membranes for dyes were almost all greater than 95.0%, while the rejection for sodium sulfate (Na2SO4) was only about 17.0%, which indicated that the modified membrane had an impressive potential application for dye desalination and purification.

Determination of 200 °C Isothermal Section of Al-Ag-Ga Phase Diagram by Microanalysis, X-ray Diffraction, Hardness and Electrical Conductivity Measurements

NASA Astrophysics Data System (ADS)

Premović, Milena; Tomović, Milica; Minić, Duško; Manasijević, Dragan; Živković, Dragana; Ćosović, Vladan; Grković, Vladan; Đorđević, Aleksandar

2017-04-01

Ternary Al-Ag-Ga system at 200 °C was experimentally and thermodynamically assessed. Isothermal section was extrapolated using optimized thermodynamic parameters for constitutive binary systems. Microstructure and phase composition of the selected alloy samples were analyzed using light microscopy, scanning electron microscopy combined with energy-dispersive spectrometry and x-ray powder diffraction technique. The obtained experimental results were found to be in a close agreement with the predicted phase equilibria. Hardness and electrical conductivity of the alloy samples from four vertical sections Al-Ag80Ga20, Al-Ag60Ga40, Ag-Al80Ga20 and Ag-Al60Ga40 of the ternary Al-Ag-Ga system at 200 °C were experimentally determined using Brinell method and eddy current measurements. Additionally, hardness of the individual phases present in the microstructure of the studied alloy samples was determined using Vickers microhardness test. Based on experimentally obtained results, isolines of Brinell hardness and electrical conductivity were calculated for the alloys from isothermal section of the ternary Al-Ag-Ga system at 200 °C.

A deterministic model of electron transport for electron probe microanalysis

NASA Astrophysics Data System (ADS)

Bünger, J.; Richter, S.; Torrilhon, M.

2018-01-01

Within the last decades significant improvements in the spatial resolution of electron probe microanalysis (EPMA) were obtained by instrumental enhancements. In contrast, the quantification procedures essentially remained unchanged. As the classical procedures assume either homogeneity or a multi-layered structure of the material, they limit the spatial resolution of EPMA. The possibilities of improving the spatial resolution through more sophisticated quantification procedures are therefore almost untouched. We investigate a new analytical model (M 1-model) for the quantification procedure based on fast and accurate modelling of electron-X-ray-matter interactions in complex materials using a deterministic approach to solve the electron transport equations. We outline the derivation of the model from the Boltzmann equation for electron transport using the method of moments with a minimum entropy closure and present first numerical results for three different test cases (homogeneous, thin film and interface). Taking Monte Carlo as a reference, the results for the three test cases show that the M 1-model is able to reproduce the electron dynamics in EPMA applications very well. Compared to classical analytical models like XPP and PAP, the M 1-model is more accurate and far more flexible, which indicates the potential of deterministic models of electron transport to further increase the spatial resolution of EPMA.

Selection of bioindicators to detect lead pollution in Ebro delta microbial mats, using high-resolution microscopic techniques.

PubMed

Maldonado, J; Solé, A; Puyen, Z M; Esteve, I

2011-07-01

Lead (Pb) is a metal that is non-essential to any metabolic process and, moreover, highly deleterious to life. In microbial mats - benthic stratified ecosystems - located in coastal areas, phototrophic microorganisms (algae and oxygenic phototrophic bacteria) are the primary producers and they are exposed to pollution by metals. In this paper we describe the search for bioindicators among phototrophic populations of Ebro delta microbial mats, using high-resolution microscopic techniques that we have optimized in previous studies. Confocal laser scanning microscopy coupled to a spectrofluorometric detector (CLSM-λscan) to determine in vivo sensitivity of different cyanobacteria to lead, and scanning electron microscopy (SEM) and transmission electron microscopy (TEM), both coupled to energy dispersive X-ray microanalysis (EDX), to determine the extra- and intracellular sequestration of this metal in cells, were the techniques used for this purpose. Oscillatoria sp. PCC 7515, Chroococcus sp. PCC 9106 and Spirulina sp. PCC 6313 tested in this paper could be considered bioindicators for lead pollution, because all of these microorganisms are indigenous, have high tolerance to high concentrations of lead and are able to accumulate this metal externally in extracellular polymeric substances (EPS) and intracellularly in polyphosphate (PP) inclusions. Experiments made with microcosms demonstrated that Phormidium-like and Lyngbya-like organisms selected themselves at the highest concentrations of lead assayed. In the present study it is shown that all cyanobacteria studied (both in culture and in microcosms) present PP inclusions in their cytoplasm and that these increase in number in lead polluted cultures and microcosms. We believe that the application of these microscopic techniques open up broad prospects for future studies of metal ecotoxicity. Copyright © 2011 Elsevier B.V. All rights reserved.

Electron Probe Microanalysis | Materials Science | NREL

Science.gov Websites

surveys of the area of interest before performing a more accurate quantitative analysis with WDS. WDS - Four spectrometers with ten diffracting crystals. The use of a single-channel analyzer allows much

Chemical State Mapping of Degraded B4C Control Rod Investigated with Soft X-ray Emission Spectrometer in Electron Probe Micro-analysis.

PubMed

Kasada, R; Ha, Y; Higuchi, T; Sakamoto, K

2016-05-10

B4C is widely used as control rods in light water reactors, such as the Fukushima Daiichi nuclear power plant, because it shows excellent neutron absorption and has a high melting point. However, B4C can melt at lower temperatures owing to eutectic interactions with stainless steel and can even evaporate by reacting with high-temperature steam under severe accident conditions. To reduce the risk of recriticality, a precise understanding of the location and chemical state of B in the melt core is necessary. Here we show that a novel soft X-ray emission spectrometer in electron probe microanalysis can help to obtain a chemical state map of B in a modeled control rod after a high-temperature steam oxidation test.

X-ray microanalysis in the scanning electron microscope.

PubMed

Roomans, Godfried M; Dragomir, Anca

2014-01-01

X-ray microanalysis conducted using the scanning electron microscope is a technique that allows the determination of chemical elements in bulk or semi-thick specimens. The lowest concentration of an element that can be detected is in the order of a few mmol/kg or a few hundred parts per million, and the smallest amount is in the order of 10(-18) g. The spatial resolution of the analysis depends on the thickness of the specimen. For biological specimen analysis, care must be taken to prevent displacement/loss of the element of interest (usually ions). Protocols are presented for the processing of frozen-hydrated and freeze-dried specimens, as well as for the analysis of small volumes of fluid, cell cultures, and other specimens. Aspects of qualitative and quantitative analysis are covered, including limitations of the technique.

X-ray microanalysis in the scanning electron microscope.

PubMed

Roomans, Godfried M; Dragomir, Anca

2007-01-01

X-ray microanalysis conducted using the scanning electron microscope is a technique that allows the determination of chemical elements in bulk or semithick specimens. The lowest concentration of an element that can be detected is in the order of a few mmol/kg or a few hundred parts per million, and the smallest amount is in the order of 10(-18) g. The spatial resolution of the analysis depends on the thickness of the specimen. For biological specimen analysis, care must be taken to prevent displacement/loss of the element of interest (usually ions). Protocols are presented for the processing of frozen-hydrated and freeze-dried specimens, as well as for the analysis of small volumes of fluid, cell cultures and other specimens. Aspects of qualitative and quantitative analysis are covered, including limitations of the technique.

Calcium transport mechanism in molting crayfish revealed by microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mizuhira, V.; Ueno, M.

1983-01-01

Crayfish provide a good model in which to study the transport mechanism of Ca ions. During the molting stage, decalcified Ca ions are transferred into the blood and accumulate in the gastrolith epithelium, after which a gastrolith is formed on the surface of the epithelium. The gastrolith is dissolved in the stomach after molting, and the Ca is reabsorbed and redistributed throughout the newly formed exoskeleton. We studied the mechanism of Ca transport by cytochemical precipitation of Ca ions and by electron microanalysis, including X-ray microanalysis (EDX) and electron energy-loss spectroscopy (EELS), with a computer. In EDX analysis, the finemore » precipitates of K-antimonate in the gastrolith mitochondria clearly defined Ca with antimony; we also observed a large amount of Ca-oxalate in the mitochondria, and Ca-K X-ray pulses were clearly defined. Ca-K X-rays were also detected from fresh freeze-substituted mitochondria. Finally, we succeeded in taking a Ca-L EELS image from the mitochondria of fresh freeze-substituted thin sections. Only a very small amount of Ca was detected from the cell membrane and other organelles. Ca-adenosine triphosphatase (ATPase) and Mg-ATPase activity was also very clearly demonstrated in the mitochondria. These enzymes may play an important role in Ca metabolism.« less

Comparison of Cliff-Lorimer-Based Methods of Scanning Transmission Electron Microscopy (STEM) Quantitative X-Ray Microanalysis for Application to Silicon Oxycarbides Thin Films.

PubMed

Parisini, Andrea; Frabboni, Stefano; Gazzadi, Gian Carlo; Rosa, Rodolfo; Armigliato, Aldo

2018-06-01

In this work, we compare the results of different Cliff-Lorimer (Cliff & Lorimer 1975) based methods in the case of a quantitative energy dispersive spectrometry investigation of light elements in ternary C-O-Si thin films. To determine the Cliff-Lorimer (C-L) k-factors, we fabricated, by focused ion beam, a standard consisting of a wedge lamella with a truncated tip, composed of two parallel SiO2 and 4H-SiC stripes. In 4H-SiC, it was not possible to obtain reliable k-factors from standard extrapolation methods owing to the strong CK-photon absorption. To overcome this problem, an extrapolation method exploiting the shape of the truncated tip of the lamella is proposed herein. The k-factors thus determined, were then used in an application of the C-L quantification procedure to a defect found at the SiO2/4H-SiC interface in the channel region of a metal-oxide field-effect-transistor device. As in this procedure, the sample thickness is required, a method to determine this quantity from the averaged and normalized scanning transmission electron microscopy intensity is also detailed. Monte Carlo simulations were used to investigate the discrepancy between experimental and theoretical k-factors and to bridge the gap between the k-factor and the Watanabe and Williams ζ-factor methods (Watanabe & Williams, 2006).

Synthesis, characterization and effect of calcination temperature on phase transformation and photocatalytic activity of Cu,S-codoped TiO 2 nanoparticles

NASA Astrophysics Data System (ADS)

Hamadanian, M.; Reisi-Vanani, A.; Majedi, A.

2010-01-01

A novel copper and sulfur codoped TiO 2 photocatalyst was synthesized by modified sol-gel method using titanium(IV) isopropoxide, CuCl 2·2H 2O and thiourea as precursors. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray micro-analysis (SEM-EDX), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) analysis. The XRD results showed undoped and Cu,S-codoped TiO 2 nanoparticles only include anatase phase. Effect of calcination temperature showed rutile phase appears in 650 and 700 °C for undoped and 0.1% Cu,S-codoped TiO 2, respectively. The SEM analysis revealed the doping of Cu and S does not leave any change in morphology of the catalyst surface. The increase of copper doping enhanced "red-shift" in the UV-vis absorption spectra. The TEM images confirmed the dopants suppressed the growth of TiO 2 grains. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. The results showed photocatalytic activity of the catalysts with 0.05% Cu,0.05% S and 0.1% Cu,0.05% S were higher than that of other catalysts under ultraviolet (UV) and visible irradiation, respectively. Because of synergetic effect of S and Cu, the Cu,S-codoped TiO 2 catalyst has higher activity than undoped and Cu or S doped TiO 2 catalysts.

Source identification of individual soot agglomerates in Arctic air by transmission electron microscopy

NASA Astrophysics Data System (ADS)

Weinbruch, S.; Benker, N.; Kandler, K.; Schütze, K.; Kling, K.; Berlinger, B.; Thomassen, Y.; Drotikova, T.; Kallenborn, R.

2018-01-01

Individual soot agglomerates collected at four different locations on the Arctic archipelago Svalbard (Norway) were characterised by transmission electron microscopy and energy-dispersive X-ray microanalysis. For source identification of the ambient soot agglomerates, samples from different local sources (coal burning power plants in Longyearbyen and Barentsburg, diesel and oil burning for power generation in Sveagruva and Ny Ålesund, cruise ship) as well as from other sources which may contribute to Arctic soot concentrations (biomass burning, aircraft emissions, diesel engines) were investigated. Diameter and graphene sheet separation distance of soot primary particles were found to be highly variable within each source and are not suited for source identification. In contrast, concentrations of the minor elements Si, P, K, Ca and Fe showed significant differences which can be used for source attribution. The presence/absence of externally mixed particle groups (fly ashes, tar balls, mercury particles) gives additional hints about the soot sources. Biomass/wood burning, ship emissions and coal burning in Barentsburg can be excluded as major source for ambient soot at Svalbard. The coal power plant in Longyearbyen is most likely a major source of soot in the settlement of Longyearbyen but does not contribute significantly to soot collected at the Global Atmosphere Watch station Zeppelin Mountain near Ny Ålesund. The most probable soot sources at Svalbard are aircraft emissions and diesel exhaust as well as long range transport of coal burning emissions.

Elemental imaging at the nanoscale: NanoSIMS and complementary techniques for element localisation in plants.

PubMed

Moore, Katie L; Lombi, Enzo; Zhao, Fang-Jie; Grovenor, Chris R M

2012-04-01

The ability to locate and quantify elemental distributions in plants is crucial to understanding plant metabolisms, the mechanisms of uptake and transport of minerals and how plants cope with toxic elements or elemental deficiencies. High-resolution secondary ion mass spectrometry (SIMS) is emerging as an important technique for the analysis of biological material at the subcellular scale. This article reviews recent work using the CAMECA NanoSIMS to determine elemental distributions in plants. The NanoSIMS is able to map elemental distributions at high resolution, down to 50 nm, and can detect very low concentrations (milligrams per kilogram) for some elements. It is also capable of mapping almost all elements in the periodic table (from hydrogen to uranium) and can distinguish between stable isotopes, which allows the design of tracer experiments. In this review, particular focus is placed upon studying the same or similar specimens with both the NanoSIMS and a wide range of complementary techniques, showing how the advantages of each technique can be combined to provide a fuller data set to address complex scientific questions. Techniques covered include optical microscopy, synchrotron techniques, including X-ray fluorescence and X-ray absorption spectroscopy, transmission electron microscopy, electron probe microanalysis, particle-induced X-ray emission and inductively coupled plasma mass spectrometry. Some of the challenges associated with sample preparation of plant material for SIMS analysis, the artefacts and limitations of the technique and future trends are also discussed.

Quantitative determination of low-Z elements in single atmospheric particles on boron substrates by automated scanning electron microscopy-energy-dispersive X-ray spectrometry.

PubMed

Choël, Marie; Deboudt, Karine; Osán, János; Flament, Pascal; Van Grieken, René

2005-09-01

Atmospheric aerosols consist of a complex heterogeneous mixture of particles. Single-particle analysis techniques are known to provide unique information on the size-resolved chemical composition of aerosols. A scanning electron microscope (SEM) combined with a thin-window energy-dispersive X-ray (EDX) detector enables the morphological and elemental analysis of single particles down to 0.1 microm with a detection limit of 1-10 wt %, low-Z elements included. To obtain data statistically representative of the air masses sampled, a computer-controlled procedure can be implemented in order to run hundreds of single-particle analyses (typically 1000-2000) automatically in a relatively short period of time (generally 4-8 h, depending on the setup and on the particle loading). However, automated particle analysis by SEM-EDX raises two practical challenges: the accuracy of the particle recognition and the reliability of the quantitative analysis, especially for micrometer-sized particles with low atomic number contents. Since low-Z analysis is hampered by the use of traditional polycarbonate membranes, an alternate choice of substrate is a prerequisite. In this work, boron is being studied as a promising material for particle microanalysis. As EDX is generally said to probe a volume of approximately 1 microm3, geometry effects arise from the finite size of microparticles. These particle geometry effects must be corrected by means of a robust concentration calculation procedure. Conventional quantitative methods developed for bulk samples generate elemental concentrations considerably in error when applied to microparticles. A new methodology for particle microanalysis, combining the use of boron as the substrate material and a reverse Monte Carlo quantitative program, was tested on standard particles ranging from 0.25 to 10 microm. We demonstrate that the quantitative determination of low-Z elements in microparticles is achievable and that highly accurate results can be obtained using the automatic data processing described here compared to conventional methods.

Type 1 diabetes mellitus effects on dental enamel formation revealed by microscopy and microanalysis.

PubMed

Silva, Bruna Larissa Lago; Medeiros, Danila Lima; Soares, Ana Prates; Line, Sérgio Roberto Peres; Pinto, Maria das Graças Farias; Soares, Telma de Jesus; do Espírito Santo, Alexandre Ribeiro

2018-03-01

Type 1 diabetes mellitus (T1DM) largely affects children, occurring therefore at the same period of deciduous and permanent teeth development. The aim of this work was to investigate birefringence and morphology of the secretory stage enamel organic extracellular matrix (EOECM), and structural and mechanical features of mature enamel from T1DM rats. Adult Wistar rats were maintained alive for a period of 56 days after the induction of experimental T1DM with a single dose of streptozotocin (60 mg/kg). After proper euthanasia of the animals, fixed upper incisors were accurately processed, and secretory stage EOECM and mature enamel were analyzed by transmitted polarizing and bright field light microscopies (TPLM and BFLM), energy-dispersive x-ray (EDX) analysis, scanning electron microscopy (SEM), and microhardness testing. Bright field light microscopies and transmitted polarizing light microscopies showed slight morphological changes in the secretory stage EOECM from diabetic rats, which also did not exhibit statistically significant alterations in birefringence brightness when compared to control animals (P > .05). EDX analysis showed that T1DM induced statistically significant little increases in the amount of calcium and phosphorus in outer mature enamel (P < .01) with preservation of calcium/phosphorus ratio in that structure (P > .05). T1DM also caused important ultrastructural alterations in mature enamel as revealed by SEM and induced a statistically significant reduction of about 13.67% in its microhardness at 80 μm from dentin-enamel junction (P < .01). This study shows that T1DM may disturb enamel development, leading to alterations in mature enamel ultrastructure and in its mechanical features. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study

PubMed Central

Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

2016-01-01

Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca2+ after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca2+, and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca2+ was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca2+ homeostasis in mesophyll cells. PMID:26957564

Three-dimensional characterization of ODS ferritic steel using by FIB-SEM serial sectioning method.

PubMed

Endo, T; Sugino, Y; Ohono, N; Ukai, S; Miyazaki, N; Wang, Y; Ohnuki, S

2014-11-01

Considerable attention has been paid to the research of the electron tomography due to determine the three-dimensional (3D) structure of materials [1]. One of the electron tomography techniques, focused ion beam/scanning electron microscopy (FIB-SEM) imaging has advantages of high resolutions (10 nm), large area observation (μm order) and simultaneous energy dispersive x- ray microanalysis (EDS)/ electron backscatter diffraction (EBSD) analysis. The purpose of this study, three-dimensional EBSD analysis of ODS ferritic steel which carried out cold work using FIB-SEM equipment was conducted, and it aimed at analyzing the microstructure obtained there. The zone annealing tests were conducted for ferritic steel [2,3], which were produced through mechanical alloying and hot-extrusion. After zone annealing, specimens were mechanically polished with #400∼4000 emery paper, 1 µm diamond paste and alumina colloidal silica. The serial sectioning and the 3D-electron backscattering diffraction (3D-EBSD) analysis were carried out. We made the micro pillar (30 x 30 x 15 µm). The EBSD measurements were carried out in each layer after serial sectioning at a step size and milling depth was 80 nm with 30 slices. After EBSD analysis, the series of cross-sectional images were aligned according to arbitrarily specified areas and then stacked up to form a volume. Consequently, we obtained the 3D-IPF maps for ODS ferritic steel. In this specimen, the {111} and {001} grains are layered by turns. In addition, the volume fraction value of both plane are similar. The aspect ratio increases with specimen depth. The 3D-EBSD mapping is useful to analysis of the bulk material since this method obtain many microstructure information, such a shape, volume and orientation of the crystal, grain boundary. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Electron probe microanalysis of calcium release and magnesium uptake by endoplasmic reticulum in bee photoreceptors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baumann, O.; Walz, B.; Somlyo, A.V.

Honey bee photoreceptors contain large sacs of endoplasmic reticulum (ER) that can be located unequivocally in freeze-dried cryosections. The elemental compositon of the ER was determined by electron probe x-ray microanalysis and was visualized in high-resolution x-ray maps. In the ER of dark-adapted photoreceptors, the Ca concentration was 47.5 {plus minus} 1.1 mmol/kg (dry weight). During a 3-sec nonsaturating light stimulus, {approximately}50% of the Ca content was released from the ER. Light stimulation also caused a highly significant increase in the Mg content of the ER; the ratio of Mg uptake to Ca released was {approximately}0.7. Our results show unambiguouslymore » that the ER is the source of Ca{sup 2+} release during cell stimulation and suggest the Mg{sup 2+} can nearly balance the charge movement of Ca{sup 2+}.« less

Microbeam X-ray analysis in Poland - past and future

NASA Astrophysics Data System (ADS)

Kusinski, J.

2010-02-01

The article provides an overview of the development of electron beam X-ray microanalysis (EPMA) in Poland. Since the introduction by Prof. Bojarski of EMPA over 45 years ago, tremendous advances in methodologies and in instrumentation have been made in order to improve the precision of quantitative compositional analysis, spatial resolution and analytical sensitivity. This was possible due to the activity of Applied Crystallography Committee at the Polish Academy of Sciences, as well as the groups of researches working in the Institute for Ferrous Metallurgy (Gliwice), the Technical University of Warsaw, the Silesian Technical University (Katowice), the AGH-University of Sciences and Technology (Krakow), and the Institute of Materials Science and Metallurgy Polish Academy of Sciences (Krakow). Based on the research examples realized by these teams, conferences, seminars and congresses organized, as well as books and academic textbooks issued, the evolution of electron beam X-ray microanalysis in Poland is demonstrated.

Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9

NASA Technical Reports Server (NTRS)

Morris, R. V.; Golden, D. C.; Lauer, H. V. Jr; Adams, J. B.

1993-01-01

We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

Spatially-Resolved Analyses of Aerodynamic Fallout from a Uranium-Fueled Nuclear Test

DOE PAGES

Lewis, L. A.; Knight, K. B.; Matzel, J. E.; ...

2015-07-28

The fiive silicate fallout glass spherules produced in a uranium-fueled, near-surface nuclear test were characterized by secondary ion mass spectrometry, electron probe microanalysis, autoradiography, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Several samples display compositional heterogeneity suggestive of incomplete mixing between major elements and natural U ( 238U/ 235U = 0.00725) and enriched U. Samples exhibit extreme spatial heterogeneity in U isotopic composition with 0.02 < 235U/ 238U < 11.84 among all five spherules and 0.02 < 235U/ 238U < 7.41 within a single spherule. Moreover, in two spherules, the 235U/ 238U ratio is correlated with changes in major elementmore » composition, suggesting the agglomeration of chemically and isotopically distinct molten precursors. Two samples are nearly homogenous with respect to major element and uranium isotopic composition, suggesting extensive mixing possibly due to experiencing higher temperatures or residing longer in the fireball. Linear correlations between 234U/ 238U, 235U/ 238U, and 236U/ 238U ratios are consistent with a two-component mixing model, which is used to illustrate the extent of mixing between natural and enriched U end members.« less

Structural, morphological and interfacial characterization of Al-Mg/TiC composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Contreras, A.; Angeles-Chavez, C.; Flores, O.

2007-08-15

Morphological and structural characterization of Al-Mg/TiC composites obtained by infiltration process and wetting by the sessile drop technique were studied. Focusing at the interface, wetting of TiC substrates by molten Al-Mg-alloys at 900 deg. C was investigated. Electron probe microanalysis (EPMA) indicated that aluminum carbide (Al{sub 4}C{sub 3}) is formed at the interface and traces of TiAl{sub 3} in the wetting assemblies were detected. Scanning Electron Microscopy (SEM) observations show that TiC particles do not appear to be uniformly attacked to produce a continuous layer of Al{sub 4}C{sub 3} at the interface. Molten Al-Mg-alloys were infiltrated into TiC preforms withmore » flowing argon at a temperature of 900 deg. C. In the composites no reaction phase was observed by SEM. Quantification of the Al phase in the composite was carried out by X-ray diffraction (XRD) and Rietveld analysis. Chemical mapping analyzed by SEM shows that the Al-Mg alloy surrounds TiC particles. In the composites with 20 wt.% of Mg the Al-Mg-{beta} phase was detected through XRD.« less

Synthesis and characterization of nanocrystalline apatites from solution modeling human blood

NASA Astrophysics Data System (ADS)

Solodyankina, Anna; Nikolaev, Anton; Frank-Kamenetskaya, Olga; Golovanova, Olga

2016-09-01

Present paper is devoted to the research of the calcification processes in the blood plasma of human body. Spontaneous crystallization from the solution modeling the inorganic part of the blood plasma has been carried out. Obtained precipitates were studied by the various instrumental methods (X-ray powder diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, electron probe microanalysis and gas-volumetric method). All gathered data allow to summarize that nonstoichiometric carbonated hydroxyapatite with low crystallinity (CSD lengths 18-28 nm), high water content and small amount of chlorine ion was obtained throughout the syntheses. Part of vacancies at the Ca sites varies from 0.17 to 0.87; the value of the Cat/(P + C) ratio-from 1.52 to 1.64 (where Cat = Ca2+ + Na+ + K+ + Mg2+). The poor crystallized synthetic apatites with high carbonate ion content (from 4.34 to 5.54 wt%) and c parameter (6.888-6.894 Å) are analogues of the apatites of the pathological cardiovascular deposits. They can be obtained from the solution modeling human blood plasma by the inorganic components with calcium phosphate supersaturation 25 and 50 and with 10 and 12 weeks experiment time.

Electrochemical Characteristics of a Diamond-Like-Carbon-Coated LiV3O8 Cathode When Used in a Li-Metal Battery with a Li-Powder Anode

NASA Astrophysics Data System (ADS)

Lee, Jae Ha; Lee, Jun Kyu; Yoon, Woo Young

2013-10-01

A diamond-like-carbon (DLC)-coated LiV3O8 cathode was synthesized for use in a rechargeable 2032-coin-type cell with a Li-powder electrode (LPE) as the anode. The LPE anode was produced using the droplet emulsion technique and was compacted by pressing. The initial discharge capacity of the LPE/DLC-coated LiV3O8 (LVO) cell was 238 mAh g-1 at a C-rate of 0.5, while that of a LPE/bare-LVO cell was 236 mAh g-1. After 50 cycles, the capacity retention rate of the DLC-coated-electrode-containing cell (92%) was higher than that of the uncoated-electrode-containing cell (77%). Results of electron probe microanalysis and Raman spectroscopy confirmed that the electrode had been coated with DLC. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to determine the sequence of formation of byproducts on the electrode after charging/discharging and to determine its surface composition. The voltage profile and impedance of the DLC-coated-electrode-containing cell were analyzed to determine the electrochemical characteristics of the DLC-coated cathode.

The effect of organic ligands on the crystallinity of calcium phosphate

NASA Astrophysics Data System (ADS)

van der Houwen, Jacqueline A. M.; Cressey, Gordon; Cressey, Barbara A.; Valsami-Jones, Eugenia

2003-03-01

Calcium phosphate phases precipitated under critical supersaturation were identified and studied in detail using X-ray powder diffraction, electron probe microanalysis, infrared spectroscopy (IR) and transmission electron microscopy. These synthetic calcium phosphates formed by spontaneous precipitation at pH 7, 25°C and 0.1 M ionic strength (NaCl as the background electrolyte). The combination of several methods allowed detailed characterisation of the calcium phosphates. The purpose of the work was to assess the influence of carboxylate ligands, specifically acetate and citrate, on the quality of the calcium phosphate precipitate. All precipitates were identified as non-stoichiometric, calcium-deficient hydroxylapatites (HAPs), containing carbonate, HPO 42-, sodium and chloride impurities. No other phases were found to be present in any of the precipitates. The presence of citrate resulted in a decrease in crystal size and a higher degree of apatite lattice imperfection in the precipitated HAP. Furthermore, IR spectroscopy showed a higher amount of carbonate present in that HAP, compared with the ones formed in the control and acetate experiments. An additional absorption band, in the infrared spectrum of the HAP formed in the presence of citrate, was observed at 1570 cm -1; this is interpreted as carboxyl groups bound to HAP.

Effects of Tungsten Addition on the Microstructure and Corrosion Resistance of Fe-3.5B Alloy in Liquid Zinc

PubMed Central

Liu, Xin; Wang, Mengmeng; Yin, Fucheng; Ouyang, Xuemei; Li, Zhi

2017-01-01

The effects of tungsten addition on the microstructure and corrosion resistance of Fe-3.5B alloys in a liquid zinc bath at 520 °C were investigated by means of scanning electron microscopy, X-ray diffraction and electron probe micro-analysis. The microstructure evolution in different alloys is analyzed and discussed using an extrapolated Fe-B-W ternary phase diagram. Experimental results show that there are three kinds of borides, the reticular (Fe, W)2B, the rod-like (Fe, W)3B and flower-like FeWB. The addition of tungsten can refine the microstructure and improve the stability of the reticular borides. Besides, it is beneficial to the formation of the metastable (Fe, W)3B phase. The resultant Fe-3.5B-11W (wt %) alloy possesses excellent corrosion resistance to liquid zinc. When tungsten content exceeds 11 wt %, the formed flower-like FeWB phase destroys the integrity of the reticular borides and results in the deterioration of the corrosion resistance. Also, the corrosion failure resulting from the spalling of borides due to the initiation of micro-cracks in the grain boundary of borides is discussed in this paper. PMID:28772759

High-strength bioresorbable Fe–Ag nanocomposite scaffolds: Processing and properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharipova, Aliya; Skolkovo Institute of Science and Technology, Skolkovo, 143025; Psakhie, Sergey G.

2015-10-27

High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na{sub 2}SO{sub 4} and K{sub 2}CO{sub 3} salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy’s law. Scaffolds with 50%more » and 55% porosity exhibited high compressive strength (18–22 MPa), compressive strength of 8–12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6{sup −6} cm{sup 2}) is close to the range of trabecular bone.« less

Examination of Libby, Montana, Fill Material for Background Levels of Amphibole from the Rainy Creek Complex Using Scanning Electron Microscopy and X-Ray Microanalysis

USGS Publications Warehouse

Adams, David T.; Langer, William H.; Hoefen, Todd M.; Van Gosen, Bradley S.; Meeker, Gregory P.

2010-01-01

Natural background levels of Libby-type amphibole in the sediment of the Libby valley in Montana have not, up to this point, been determined. The purpose of this report is to provide the preliminary findings of a study designed by both the U.S. Geological Survey and the U.S. Environmental Protection Agency and performed by the U.S. Geological Survey. The study worked to constrain the natural background levels of fibrous amphiboles potentially derived from the nearby Rainy Creek Complex. The material selected for this study was sampled from three localities, two of which are active open-pit sand and gravel mines. Seventy samples were collected in total and examined using a scanning electron microscope equipped with an energy dispersive x-ray spectrometer. All samples contained varying amounts of feldspars, ilmenite, magnetite, quartz, clay minerals, pyroxene minerals, and non-fibrous amphiboles such as tremolite, actinolite, and magnesiohornblende. Of the 70 samples collected, only three had detectable levels of fibrous amphiboles compatible with those found in the rainy creek complex. The maximum concentration, identified here, of the amphiboles potentially from the Rainy Creek Complex is 0.083 percent by weight.

Interfacial microanalysis of rubber tyre-cord adhesion and the influence of cobalt

NASA Astrophysics Data System (ADS)

Fulton, W. Stephen; Smith, Graham C.; Titchener, Keith J.

2004-01-01

The effect of cobalt-containing adhesion promoters on the structure and morphology of rubber-brass and rubber-tyre-cord interfaces before and after ageing has been investigated by X-ray photoelectron spectroscopy (XPS) depth profiling, glancing incidence X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect the cobalt adhesion promoters had upon the interface morphology as they suppressed the growth of crystalline dendrites normally associated with the ageing process was imaged in TEM using samples prepared by the focused ion beam (FIB) milling technique. XPS depth profiling through the interfaces revealed that different types of adhesion promoter influenced the amount and distribution of cobalt ions in the bonding layer. XRD demonstrated the influence that cobalt had upon the structure of the interface and subsequent crystallinity, with a lesser degree of crystallinity being associated with better adhesion performance. From the results a model for the effect of the Co chemistry of the adhesion promotor has been developed.

Histopathologic and Ultrastructural Features of Gold Thread Implanted in the Skin for Facial Rejuvenation.

PubMed

Moulonguet, Isabelle; Arnaud, Eric; Plantier, Françoise; da Costa, Patrick; Zaleski, Stéphane

2015-10-01

The authors report the histopathologic and ultrastructural features of gold threads, which were implanted in the cheek subcutis of a 77-year-old woman 10 years ago. These particles did not give rise to any adverse reactions and were fortuitously discovered by the surgeon during a facelift. Histopathology showed a nonpolarizing exogenous material consisting of black oval structures surrounded by a capsule of fibrosis and by a discrete inflammatory reaction with a few giant cells. In some cases, only a long fibrous tract surrounded by a moderate mononucleate infiltrate was observed. The wires were characterized with scanning electron microscopy, and X-ray microanalysis revealed a specific peak at 2.2 keV representative of gold that was absent in the control skin sample. As this value is specific for gold, it confirms the presence of the metal in the patient's skin. The histopathologic appearance of gold threads is particularly distinctive and easily recognizable by dermatopathologists.

Internal structure of cesium-bearing radioactive microparticles released from Fukushima nuclear power plant

PubMed Central

Yamaguchi, Noriko; Mitome, Masanori; Kotone, Akiyama-Hasegawa; Asano, Maki; Adachi, Kouji; Kogure, Toshihiro

2016-01-01

Microparticles containing substantial amounts of radiocesium collected from the ground in Fukushima were investigated mainly by transmission electron microscopy (TEM) and X-ray microanalysis with scanning TEM (STEM). Particles of around 2 μm in diameter are basically silicate glass containing Fe and Zn as transition metals, Cs, Rb and K as alkali ions, and Sn as substantial elements. These elements are homogeneously distributed in the glass except Cs which has a concentration gradient, increasing from center to surface. Nano-sized crystallites such as copper- zinc- and molybdenum sulfide, and silver telluride were found inside the microparticles, which probably resulted from the segregation of the silicate and sulfide (telluride) during molten-stage. An alkali-depleted layer of ca. 0.2 μm thick exists at the outer side of the particle collected from cedar leaves 8 months after the nuclear accident, suggesting gradual leaching of radiocesium from the microparticles in the natural environment. PMID:26838055

Crystal structure of (Mo,W){sub 9}O{sub 25}, homologue of the Mo{sub 4}O{sub 11} (Orthorhombic)-type structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

D`Yachenko, O.G.; Tabachenko, V.V.; Sundberg, M.

The structure of Mo{sub 7.6}W{sub 1.4}O{sup 25} has been determined from single crystal X-ray data. The symmetry is monoclinic with lattice parameters a = 5.448(1), b = 27.639(8), c = 6.739 (1) {angstrom}, {beta} = 90.180(9){degrees}, and space group P2{sub 1}/n. The refinement led to R = 0.046 for 2060 observed unique reflections. The Mo:W ratio was confirmed by microanalysis. The (Mo, W){sub 9}O{sub 25} structure is built up of cornersharing distorted MO{sub 6} octahedra in slabs of ReO{sub 3}-type, cut parallel to (211) and seven octahedra wide along two subcell axes. The slabs appear alternatively in mirrored orientations. Themore » slabs are mutually linked by corner sharing of fairly regular MoO{sub 4} tetrahedra so that five-sided tunnels are formed. High-resolution electron microscopy images showed well-ordered crystal fragments.« less

Characterization of morphology and composition of inorganic fillers in dental alginates.

PubMed

Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

2014-01-01

Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450(°)C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C-81.59%, H-79.89%, O-78.87%, H5-77.95%, JP-66.88%, wt). The filler fractions in volume (vt) were as follows: H5-84.85%, JP-74.76%, H-70.03%, O-68.31%, and C-56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology.

Characterization of Impact Damage in Ultra-High Performance Concrete Using Spatially Correlated Nanoindentation/SEM/EDX

NASA Astrophysics Data System (ADS)

Moser, R. D.; Allison, P. G.; Chandler, M. Q.

2013-12-01

Little work has been done to study the fundamental material behaviors and failure mechanisms of cement-based materials including ordinary Portland cement concrete and ultra-high performance concretes (UHPCs) under high strain impact and penetration loads at lower length scales. These high strain rate loadings have many possible effects on UHPCs at the microscale and nanoscale, including alterations in the hydration state and bonding present in phases such as calcium silicate hydrate, in addition to fracture and debonding. In this work, the possible chemical and physical changes in UHPCs subjected to high strain rate impact and penetration loads were investigated using a novel technique wherein nanoindentation measurements were spatially correlated with images using scanning electron microscopy and chemical composition using energy dispersive x-ray microanalysis. Results indicate that impact degrades both the elastic modulus and indentation hardness of UHPCs, and in particular hydrated phases, with damage likely occurring due to microfracturing and debonding.

Controversial Suicide Case Using a Submachine Gun with a Sound Suppressor-The Need of Team Work of Forensic Chemistry and Firearm Examiners.

PubMed

Brożek-Mucha, Zuzanna; Zdeb, Krzysztof

2018-05-01

Evidence materials in a presumed suicide case were studied by a firearm examiner and a forensic chemist. The victim's body with double gunshot wounding in his forehead, a machine gun in the sustained fire mode with a silencer, and four cartridge cases were found. Examinations of the evidence, the case file studies, and experiments dedicated to the case were carried out. Relationships between the placement of cartridge cases and the gun were established using a fast camera. The distributions of gunshot residues on the evidence materials and within the comparative gunshot patterns were studied by means of optical and electron microscopy, X-ray microanalysis, and infrared spectroscopy. The shooting distance was assessed to be 30 cm or more, whereas the greatest distance that could have been achieved by the victim himself was about 11-13 cm. The obtained results supported the version of homicide rather than suicide. © 2017 American Academy of Forensic Sciences.

Identification of phases in the interaction layer between U-Mo-Zr/Al and U-Mo-Zr/Al-Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varela, C.L. Komar; Arico, S.F.; Mirandou, M.

Out-of-pile diffusion experiments were performed between U-7wt.% Mo-1wt.% Zr and Al or Al A356 (7,1wt.% Si) at 550 deg. C. In this work morphological characterization and phase identification on both interaction layer are presented. They were carried out by the use of different techniques: optical and scanning electron microscopy, X-Ray diffraction and WDS microanalysis. In the interaction layer U-7wt.% Mo-1wt.% Zr/Al, the phases UAl{sub 3}, UAl{sub 4}, Al{sub 20}Mo{sub 2}U and Al{sub 43}Mo{sub 4}U{sub 6} were identified. In the interaction layer U-7wt.% Mo-1wt.% Zr/Al A356, the phases U(Al, Si) with 25at.% Si and Si{sub 5}U{sub 3} were identified. This lastmore » phase, with a higher Si concentration, was identified with XRD Synchrotron radiation performed at the National Synchrotron Light Laboratory (LNLS), Campinas, Brasil. (author)« less

Influence of Sm2O3 microalloying and Yb contamination on Y211 particles coarsening and superconducting properties of IG YBCO bulk superconductors

NASA Astrophysics Data System (ADS)

Vojtkova, L.; Diko, P.; Kovac, J.; Vojtko, M.

2018-06-01

Single grain YBa2Cu3O7‑x (YBCO or Y123) bulk superconductors were produced by an infiltration growth process. The solid phase precursor was prepared by solid state synthesis from Y2O3 + BaCuO2 powders. The influence of the addition of Sm2O3 and YB contamination from the substrate on the microstructure and superconducting properties was analyzed. The dependences of Yb concentration on the distance from the bottom of the samples measured by energy dispersive spectroscopy microanalysis used in conjunction with scanning electron microscopy confirmed the contamination of the samples during the melting stage of the sample preparation. It is shown that the addition of Sm in low concentration and its combination with Yb from the substrate modify the coarsening of the Y211 particles as well as lead to the appearance of a secondary peak effect in the field dependences of the critical current density.

Application of electron probe X-ray microanalysis to calcification studies of bone and cartilage.

PubMed

Landis, W J

1979-01-01

The use of electron probe x-ray microanalysis in previous studies of bone and cartilage has been reviewed with emphasis on the results which have contributed to some of the current concepts of the mechanism of mineralization in these tissues. A number of investigations continuing in the author's laboratory utilizing high spatial resolution x-ray microanalysis and anhydrous methods of specimen preparation are described, including aspects concerning the derivation of calibration curves from synthetic calcium phosphate solids, qualitative and quantitative analyses of calcium and phosphorus in bone from embryonic chicks and in growth plate cartilage from rats, and the role of organically-bound phosphorus in mineralizing tissues. The data obtained have helped identify brushite, CaHPO4-2H2O, as the major crystalline solid phase of calcium phosphate in the earliest mineral deposits of bone tissue, brushite and poorly crystalline hydroxyapatite in bone mineral of increasing age, and poorly crystalline hydroxyapatite in the most mature mineral portions of the tissue. Growth plate cartilage examination has revealed calcium and phosphorus in single mitochondrial granules within chondrocytes and in certain extracellular particles distinct from matrix vesicles. These results have provided important information about the possible roles of cells, extracellular components, and the organic matrix in the regulation of mineralization and about the composition, structure, and organization of the mineral phase as a function of progressively increasing age and maturation of the tissues studied.

Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides

NASA Astrophysics Data System (ADS)

Salerno, Marco

2010-09-01

Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K3[Fe(CN)6] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO3 form.

Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides.

PubMed

Salerno, Marco

2010-09-01

Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K(3)[Fe(CN)(6)] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO(3) form.

Focussed ion beam thin sample microanalysis using a field emission gun electron probe microanalyser

NASA Astrophysics Data System (ADS)

Kubo, Y.

2018-01-01

Field emission gun electron probe microanalysis (FEG-EPMA) in conjunction with wavelength-dispersive X-ray spectrometry using a low acceleration voltage (V acc) allows elemental analysis with sub-micrometre lateral spatial resolution (SR). However, this degree of SR does not necessarily meet the requirements associated with increasingly miniaturised devices. Another challenge related to performing FEG-EPMA with a low V acc is that the accuracy of quantitative analyses is adversely affected, primarily because low energy X-ray lines such as the L- and M-lines must be employed and due to the potential of line interference. One promising means of obtaining high SR with FEG-EPMA is to use thin samples together with high V acc values. This mini-review covers the basic principles of thin-sample FEG-EPMA and describes an application of this technique to the analysis of optical fibres. Outstanding issues related to this technique that must be addressed are also discussed, which include the potential for electron beam damage during analysis of insulating materials and the development of methods to use thin samples for quantitative analysis.

Procurement of novel microanalysis equipment for construction materials.

DOT National Transportation Integrated Search

2012-02-01

The equipment procured (i.e. an Orbis micro X-ray Fluorescence (MXRF) and an APSEX personal Scanning Electron Microscope (PSEM)) is part of the next generation of micro analytical equipment. These tools have the ability to make large volumes of...

Synthesis and characterisation of PuPO4 - a potential analytical standard for EPMA actinide quantification

NASA Astrophysics Data System (ADS)

Wright, K. E.; Popa, K.; Pöml, P.

2018-01-01

Transmutation nuclear fuels contain weight percentage quantities of actinide elements, including Pu, Am and Np. Because of the complex spectra presented by actinide elements using electron probe microanalysis (EPMA), it is necessary to have relatively pure actinide element standards to facilitate overlap correction and accurate quantitation. Synthesis of actinide oxide standards is complicated by their multiple oxidation states, which can result in inhomogeneous standards or standards that are not stable at atmospheric conditions. Synthesis of PuP4 results in a specimen that exhibits stable oxidation-reduction chemistry and is sufficiently homogenous to serve as an EPMA standard. This approach shows promise as a method for producing viable actinide standards for microanalysis.

Enhanced ionic conductivity in planar sodium-β"-alumina electrolyte for electrochemical energy storage applications.

PubMed

La Rosa, Daniela; Monforte, Giuseppe; D'Urso, Claudia; Baglio, Vincenzo; Antonucci, Vincenzo; Aricò, Antonino S

2010-12-17

Solid Na-β"-Al₂O₃ electrolyte is prepared by a simple chemical route involving a pseudo-boehmite precursor and thermal treatment. Boehmite powder is used for manufacturing the planar electrolyte with appropriate bulk density after firing at 1500 °C. The structure, morphology, and surface properties of precursor powders and sintered electrolytes are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). As shown by XRD and TEM analyses, nanometer-sized particles are obtained for the boehmite precursor and a pure crystallographic phase is achieved for the sintered electrolyte. SEM analysis of the cross-section indicates good sintering characteristics. XPS shows a higher Na/Al atomic ratio on the surface for the planar electrolyte compared to a commercial tubular electrolyte (0.57 vs. 0.46). Energy-dispersive X-ray microanalysis (EDX) shows an Na/Al ratio in the bulk of 0.16, similar in the two samples. The ionic conductivity of the planar electrolyte is larger than that measured on a commercial tube of sodium-β"-alumina in a wide temperature range. At 350 °C, conductivity values of 0.5 S cm⁻¹ and 0.26 S cm⁻¹ are obtained for the planar electrolyte and the commercial tube, respectively. AC-impedance spectra show smaller grain boundary effects in the planar electrolyte than in the tubular electrolyte. These favorable properties may increase the perspectives for applying planar Na-β"-Al₂O₃ electrolytes in high-temperature batteries.

Characterization of As-polluted soils by laboratory X-ray-based techniques coupled with sequential extractions and electron microscopy: the case of Crocette gold mine in the Monte Rosa mining district (Italy).

PubMed

Allegretta, Ignazio; Porfido, Carlo; Martin, Maria; Barberis, Elisabetta; Terzano, Roberto; Spagnuolo, Matteo

2018-06-24

Arsenic concentration and distribution were studied by combining laboratory X-ray-based techniques (wavelength dispersive X-ray fluorescence (WDXRF), micro X-ray fluorescence (μXRF), and X-ray powder diffraction (XRPD)), field emission scanning electron microscopy equipped with microanalysis (FE-SEM-EDX), and sequential extraction procedure (SEP) coupled to total reflection X-ray fluorescence (TXRF) analysis. This approach was applied to three contaminated soils and one mine tailing collected near the gold extraction plant at the Crocette gold mine (Macugnaga, VB) in the Monte Rosa mining district (Piedmont, Italy). Arsenic (As) concentration, measured with WDXRF, ranged from 145 to 40,200 mg/kg. XRPD analysis evidenced the presence of jarosite and the absence of any As-bearing mineral, suggesting a high weathering grade and strong oxidative conditions. However, small domains of Fe arsenate were identified by combining μXRF with FE-SEM-EDX. SEP results revealed that As was mainly associated to amorphous Fe oxides/hydroxides or hydroxysulfates (50-80%) and the combination of XRPD and FE-SEM-EDX suggested that this phase could be attributed to schwertmannite. On the basis of the reported results, As is scarcely mobile, even if a consistent As fraction (1-3 g As/kg of soil) is still potentially mobilizable. In general, the proposed combination of laboratory X-ray techniques could be successfully employed to unravel environmental issues related to metal(loid) pollution in soil and sediments.

In situ identification and X-ray imaging of microorganisms distribution on the Tatahouine meteorite

NASA Astrophysics Data System (ADS)

Lemelle, L.; Salomé, M.; Fialin, M.; Simionovici, A.; Gillet, Ph.

2004-10-01

Microorganisms were searched for among the complex microstructures observed on the surface of a fragment of the Tatahouine meteorite inherited from the Tunisian soil in which they were buried. In this view, the chemical compositions, particularly the nitrogen, phosphorus, and sulphur compositions, including the sulphur speciation, were investigated using scanning electron microscopy (SEM), electron probe microanalysis (EPMA) mapping, and scanning X-ray microscopy (SXM). A few 2-μm-thick filaments, partly covered by patches of calcite ensuring they were not deposited by a laboratory contamination, were observed by SEM. The EPMA maps show that the portions free of calcite of the filaments have low but constant contents of nitrogen, sulphur, and phosphorus. The SXM maps were recorded at 2473.5, 2478, and 2482.2 eV, which are respectively characteristic for amino acid linked sulphur, sulphite (SO32-), and sulphate (SO42-). The portions of the filaments detected by EPMA are also those that are enriched in amino acid linked sulphur. The calculated (N/S) elemental ratio is consistent with the one of the dehydrated Escherichia coli matter, contrary to the much lower (P/S) elemental ratio. In living cells, the bulk N and S elements are mainly located in large polymers by covalent bonds, whereas a significant amount of P belongs to small and reactive molecules. We thus can propose that the observed microstructures are dehydrated microorganisms, in which most of the elements that were composing the polymers were retained, whereas the small electrolytes and molecules were removed.

Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study.

PubMed

Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

2016-06-01

Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca(2+) after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca(2+), and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca(2+) was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca(2+) homeostasis in mesophyll cells. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

A Cover of Glass: First Report of Biomineralized Silicon in a Ciliate, Maryna umbrellata (Ciliophora: Colpodea)

PubMed Central

FOISSNER, WILHELM; WEISSENBACHER, BIRGIT; KRAUTGARTNER, WOLF-DIETRICH; LÜTZ-MEINDL, URSULA

2010-01-01

Using hydrofluoric acid, scanning electron microscope-assisted X-ray microanalysis, and energy-filtered transmission electron microscopy, we present the first definite proof of biomineralized silicon [(SiO2)]n in a ciliophoran protist, Maryna umbrellata, a common inhabitant of ephemeral pools. In the trophic specimen, the amorphic silicon (glass) granules are accumulated in the anterior half of the body. When entering the dormant stage, most glass granules are excreted to form the surface cover of the globular resting cyst. Most likely, the silicon granules are synthesized in vesicles of the Golgi apparatus. First, nanospheres with a size of 20–40 nm are formed in a fibrous matrix; they grow to be spongious complexes, eventually becoming amorphous glass granules with an average size of 819 nm × 630 nm. In the transmission electron microscope, the silicon granules show the characteristic fracture pattern of glass known from many other silicon-bearing organisms. A literature survey suggests that silicon is very rare in ciliates. The fine structure and genesis of silicon granules in M. umbrellata are very similar to those of other organisms, including vascular plants and animals, indicating a common mechanism. Light perception and protection against mechanical stress and predators might be functions of the silicon granules in M. umbrellata. The palaeontological significance of glass cysts in ciliates is also discussed. PMID:19883440

First detection of lead in black paper from intraoral film: an environmental concern.

PubMed

Guedes, Débora F C; Silva, Reginaldo S; da Veiga, Márcia A M S; Pecora, Jesus D

2009-10-30

Lead (Pb) contamination in the black paper that recovers intraoral films (BKP) has been investigated. BKP samples were collected from the Radiology Clinics of the Dental School of Ribeirão Preto, University of São Paulo, Brazil. For sake of comparison, four different methods were used. The results revealed the presence of high lead levels, well above the maximum limit allowed by the legislation. Pb contamination levels achieved after the following treatments: paper digestion in nitric acid, microwave treatment, DIN38414-54 method and TCLP method were 997 microg g(-1), 189 microg g(-1), 20.8 microg g(-1), and 54.0 microg g(-1), respectively. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma mass spectrometry (ICP-MS) were employed for lead determination according to the protocols of the applied methods. Lead contamination in used BKP was confirmed by scanning electron microscopy coupled with energy dispersive X-ray microanalysis (SEM-EDS). All the SEM imaging was carried out in the secondary electron mode (SE) and backscattered-electron mode (QBSD) following punctual X-ray fluorescence spectra. Soil contamination derived from this product revealed the urgent need of addressing this problem. These elevated Pb levels, show that a preliminary treatment of BKP is mandatory before it is disposed into the common trash. The high lead content of this material makes its direct dumping into the environment unwise.

Quantitative Electron-Excited X-Ray Microanalysis of Borides, Carbides, Nitrides, Oxides, and Fluorides with Scanning Electron Microscopy/Silicon Drift Detector Energy-Dispersive Spectrometry (SEM/SDD-EDS) and NIST DTSA-II.

PubMed

Newbury, Dale E; Ritchie, Nicholas W M

2015-10-01

A scanning electron microscope with a silicon drift detector energy-dispersive X-ray spectrometer (SEM/SDD-EDS) was used to analyze materials containing the low atomic number elements B, C, N, O, and F achieving a high degree of accuracy. Nearly all results fell well within an uncertainty envelope of ±5% relative (where relative uncertainty (%)=[(measured-ideal)/ideal]×100%). Quantification was performed with the standards-based "k-ratio" method with matrix corrections calculated based on the Pouchou and Pichoir expression for the ionization depth distribution function, as implemented in the NIST DTSA-II EDS software platform. The analytical strategy that was followed involved collection of high count (>2.5 million counts from 100 eV to the incident beam energy) spectra measured with a conservative input count rate that restricted the deadtime to ~10% to minimize coincidence effects. Standards employed included pure elements and simple compounds. A 10 keV beam was employed to excite the K- and L-shell X-rays of intermediate and high atomic number elements with excitation energies above 3 keV, e.g., the Fe K-family, while a 5 keV beam was used for analyses of elements with excitation energies below 3 keV, e.g., the Mo L-family.

Effect of Gold on the Microstructural Evolution and Integrity of a Sintered Silver Joint

DOE PAGES

Muralidharan, Govindarajan; Leonard, Donovan N.; Meyer, Harry M.

2017-01-05

There is a need for next-generation, high-performance power electronic packages and systems employing wide band gap devices to operate at high temperatures in automotive and electric grid applications. Sintered silver joints are currently being evaluated as an alternative to Pb-free solder joints. Of particular interest is the development of joints based on silver paste consisting of nanoscale or micron scale particles that can be processed without the application of an external pressure. Microstructural evolution at the interface of a pressureless sintered silver joint formed between a SiC die with a Ti/Ni/Au metallization and an Active Metal Brazed substrate with Agmore » metallization at 250 °C was evaluated using Scanning Electron Microscopy, X-ray microanalysis, and X-ray Photo Electron Spectroscopy. Results from Focused Ion Beam cross-sections show that during sintering, the pores in the sintered region close to the Au layer tend to be smaller and are oriented predominantly with their longer dimension oriented parallel to the interface. With further densification, this results in the alignment of small pores parallel to the interface, creating a path for easy crack propagation. Lastly, X-ray microchemical analyses results confirm interdiffusion between Au and Ag and that a region with poor mechanical strength is formed at the edge of this region of interdiffusion.« less

Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Microanalysis and Recognition of Micrometeoroid Compositions

NASA Technical Reports Server (NTRS)

Kearsley, A. T.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.; Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V. V.; Colaux, J. L.;

The Nanocrystalline State of Narrow Gap Semiconducting Chalcogenides

DTIC Science & Technology

2010-08-23

using a 1 nm scanning probe and the EDS microanalysis . For Annealing studies nanocrystal powder samples were placed in ceramic crucibles and annealed...nanocrystals are homogenous single phase EDS spectral images were collected in scanning transmission electron microcopy using a 1 nm electron probe...explorations with alio-valent elements (e.g. Sb3+, Ag+ doping in PbTe). • Perform chemical and physical characterization to demonstrate that nanocrystals are

Identification of sigma and chi phases in duplex stainless steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Llorca-Isern, Núria, E-mail: nullorca@ub.edu; López-Luque, Héctor, E-mail: hlopezlu7@alumnes.ub.edu; López-Jiménez, Isabel, E-mail: ilopezji9@alumnes.ub.edu

The aim of this work is to find out the most suitable method for detecting and analyzing accurately the formation conditions of secondary phases, particularly Sigma-phase (σ-phase) and Chi-phase (χ-phase) in duplex stainless steels (UNS S32205 and UNS S32750). The microstructure was characterized after a solution annealing at 1080 °C followed by an isothermal heating at 830 °C for different time ranges, ranging from 1 min to 9 h, in order to enlighten the controversial point concerning the mechanism of χ-phase nucleation in relation with the σ-phase. Etched samples were observed using optical microscopy (MO), and scanning electron microscopy (FESEM)more » with a backscattered electron detector (BSE) was used on unetched samples. Compositional microanalysis (EDS) was carried out for identifying the different phases present in the steels. Sigma phase was easily observed using different etching procedures, whereas χ-phase was only clearly detected with FESEM–BSE on unetched samples. The compositional analyses showed that the molybdenum content in χ-phase almost doubles the content of this element in σ-phase, and as a result the kinetics of nucleation and growth were also found to be remarkably faster when the alloy content in the steel is higher. In addition, chromium nitrides and carbides were also observed to precipitate as a result of the heat treatments and, in the case of the chromium nitrides, they act as a favorable site for the nucleation of σ-phase and χ-phase. - Highlights: • Microscopy was used on heat treated duplex steels for microstructure identification. • FESEM–BSE observation on unetched samples provided the best contrast between phases. • Analyses of carbides, nitrides, chi and sigma phases were possible by EDS and WDS. • Chromium nitrides act as favorable site for the nucleation of chi and sigma phases. • Secondary phases nucleation kinetics are faster in superduplex than in duplex steels.« less

X-ray microanalysis of porous materials using Monte Carlo simulations.

PubMed

Poirier, Dominique; Gauvin, Raynald

2011-01-01

Quantitative X-ray microanalysis models, such as ZAF or φ(ρz) methods, are normally based on solid, flat-polished specimens. This limits their use in various domains where porous materials are studied, such as powder metallurgy, catalysts, foams, etc. Previous experimental studies have shown that an increase in porosity leads to a deficit in X-ray emission for various materials, such as graphite, Cr(2) O(3) , CuO, ZnS (Ichinokawa et al., '69), Al(2) O(3) , and Ag (Lakis et al., '92). However, the mechanisms responsible for this decrease are unclear. The porosity by itself does not explain the loss in intensity, other mechanisms have therefore been proposed, such as extra energy loss by the diffusion of electrons by surface plasmons generated at the pores-solid interfaces, surface roughness, extra charging at the pores-solid interface, or carbon diffusion in the pores. However, the exact mechanism is still unclear. In order to better understand the effects of porosity on quantitative microanalysis, a new approach using Monte Carlo simulations was developed by Gauvin (2005) using a constant pore size. In this new study, the X-ray emissions model was modified to include a random log normal distribution of pores size in the simulated materials. This article presents, after a literature review of the previous works performed about X-ray microanalysis of porous materials, some of the results obtained with Gauvin's modified model. They are then compared with experimental results. Copyright © 2011 Wiley Periodicals, Inc.

Electrical characteristics for Sn-Ag-Cu solder bump with Ti/Ni/Cu under-bump metallization after temperature cycling tests

NASA Astrophysics Data System (ADS)

Shih, T. I.; Lin, Y. C.; Duh, J. G.; Hsu, Tom

2006-10-01

Lead-free solder bumps have been widely used in current flip-chip technology (FCT) due to environmental issues. Solder joints after temperature cycling tests were employed to investigate the interfacial reaction between the Ti/Ni/Cu under-bump metallization and Sn-Ag-Cu solders. The interfacial morphology and quantitative analysis of the intermetallic compounds (IMCs) were obtained by electron probe microanalysis (EPMA) and field emission electron probe microanalysis (FE-EPMA). Various types of IMCs such as (Cu1-x,Agx)6Sn5, (Cu1-y,Agy)3Sn, and (Ag1-z,Cuz)3Sn were observed. In addition to conventional I-V measurements by a special sample preparation technique, a scanning electron microscope (SEM) internal probing system was introduced to evaluate the electrical characteristics in the IMCs after various test conditions. The electrical data would be correlated to microstructural evolution due to the interfacial reaction between the solder and under-bump metallurgy (UBM). This study demonstrated the successful employment of an internal nanoprobing approach, which would help further understanding of the electrical behavior within an IMC layer in the solder/UBM assembly.

Microstructural Evolution and Phase Formation in 2nd-Generation Refractory-Based High Entropy Alloys

PubMed Central

Eshed, Eyal; Larianovsky, Natalya; Kovalevsky, Alexey; Popov, Vladimir; Gorbachev, Igor; Popov, Vladimir; Katz-Demyanetz, Alexander

2018-01-01

Refractory-based high entropy alloys (HEAs) of the 2nd-generation type are new intensively-studied materials with a high potential for structural high-temperature applications. This paper presents investigation results on microstructural evolution and phase formation in as-cast and subsequently heat-treated HEAs at various temperature-time regimes. Microstructural examination was performed by means of scanning electron microscopy (SEM) combined with the energy dispersive spectroscopy (EDS) mode of electron probe microanalysis (EPMA) and qualitative X-ray diffraction (XRD). The primary evolutionary trend observed was the tendency of Zr to gradually segregate as the temperature rises, while all the other elements eventually dissolve in the BCC solid solution phase once the onset of Laves phase complex decomposition is reached. The performed thermodynamic modelling was based on the Calculation of Phase Diagrams method (CALPHAD). The BCC A2 solid solution phase is predicted by the model to contain increasing amounts of Cr as the temperature rises, which is in perfect agreement with the actual results obtained by SEM. However, the model was not able to predict the existence of the Zr-rich phase or the tendency of Zr to segregate and form its own solid solution—most likely as a result of the Zr segregation trend not being an equilibrium phenomenon. PMID:29360763

Influence of Ni Interlayer on Microstructure and Mechanical Properties of Mg/Al Bimetallic Castings

NASA Astrophysics Data System (ADS)

Liu, Ning; Liu, Canchun; Liang, Chunyong; Zhang, Yongguang

2018-05-01

Dissimilar joining of magnesium and aluminum using a compound casting process was investigated in the present work. For the first time, a Ni interlayer prepared by plasma spraying was inserted between the two base metals to improve the interfacial characteristics. Examination of the interfacial regions using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe microanalysis, and X-ray diffraction revealed the formation of a three-layered interface between Mg and Al without the interlayer. The thickness of the interface was approximately 600 μm when the casting was performed at 700 °C and increased with increasing casting temperature. However, with the addition of the Ni interlayer, the Al-Mg reaction was successfully prevented, and metallurgical bonding between the Ni interlayer and two base metals was achieved at a casting temperature of 700 °C. Upon increasing this temperature, Mg-Ni and Al-Ni intermetallics were generated at the separate interfaces. The shear strength of the Mg/Al bimetallic castings with the Ni interlayer was substantially improved compared with that of the direct Mg/Al joint, with a maximum value of 25.4 MPa achieved at 700 °C. Fracture occurred mainly along the Mg/Ni interface for the Mg/Ni/Al multilayer structure castings.

Scanning and transmission electron microscope of suspended lead-rich particles in the air of San Luis Potosi, Mexico

NASA Astrophysics Data System (ADS)

Piña, A. Aragón; Villaseñor, G. Torres; Jacinto, P. Santiago; Fernández, M. Monroy

In the city of San Luis Potosi exists an important metallurgical plant and is known that in the adjacent urban zone, there is a high concentration of lead in the air, it is also supposed that most of the particles with lead have an anthropogenic origin because these particles show morphological characteristics and chemical composition very different in comparison with common lead minerals. In this work it was proved that most of the airborne particles with lead present in this urban zone, effectively came from the copper smelter. The airborne particles with lead were compared with particles with lead obtained starting from samples of slag and lead calcine of the copper smelter. To perform the comparative study, these particles were studied with energy dispersive X-ray microanalysis (EDS) in conjunction with scanning electron microscope to obtain chemical composition and associated morphological characteristics. Results suggest that these particles, composed of only one phase, are chemically distinct from any crustal lead mineral. Because of the complexity of the chemical composition of these particles (Pb, S, Cu, As, Fe, Zn, Cd, Sb, O), some of the airborne particles were analyzed by transmission microscopy in order to associate crystalline structure with any particular chemical phase.

Manganese-enhanced magnetic resonance microscopy of mineralization

USGS Publications Warehouse

Chesnick, I.E.; Todorov, T.I.; Centeno, J.A.; Newbury, D.E.; Small, J.A.; Potter, K.

2007-01-01

Paramagnetic manganese (II) can be employed as a calcium surrogate to sensitize magnetic resonance microscopy (MRM) to the processing of calcium during bone formation. At high doses, osteoblasts can take up sufficient quantities of manganese, resulting in marked changes in water proton T1, T2 and magnetization transfer ratio values compared to those for untreated cells. Accordingly, inductively coupled plasma mass spectrometry (ICP-MS) results confirm that the manganese content of treated cell pellets was 10-fold higher than that for untreated cell pellets. To establish that manganese is processed like calcium and deposited as bone, calvaria from the skull of embryonic chicks were grown in culture medium supplemented with 1 mM MnCl2 and 3 mM CaCl2. A banding pattern of high and low T2 values, consistent with mineral deposits with high and low levels of manganese, was observed radiating from the calvarial ridge. The results of ICP-MS studies confirm that manganese-treated calvaria take up increasing amounts of manganese with time in culture. Finally, elemental mapping studies with electron probe microanalysis confirmed local variations in the manganese content of bone newly deposited on the calvarial surface. This is the first reported use of manganese-enhanced MRM to study the process whereby calcium is taken up by osteoblasts cells and deposited as bone. ?? 2007 Elsevier Inc. All rights reserved.

Presence of a plant-like proton-pumping pyrophosphatase in acidocalcisomes of Trypanosoma cruzi.

PubMed

Scott, D A; de Souza, W; Benchimol, M; Zhong, L; Lu, H G; Moreno, S N; Docampo, R

1998-08-21

The vacuolar-type proton-translocating pyrophosphatase (V-H+-PPase) is an enzyme previously described in detail only in plants. This paper demonstrates its presence in the trypanosomatid Trypanosoma cruzi. Pyrophosphate promoted organellar acidification in permeabilized amastigotes, epimastigotes, and trypomastigotes of T. cruzi. This activity was stimulated by K+ ions and was inhibited by Na+ ions and pyrophosphate analogs, as is the plant activity. Separation of epimastigote extracts on Percoll gradients yielded a dense fraction that contained H+-PPase activity measured both by proton uptake and phosphate release but lacked markers for mitochondria, lysosomes, glycosomes, cytosol, and plasma membrane. Antiserum raised against specific sequences of the plant V-H+-PPase cross-reacted with a T. cruzi protein, which was also detectable in the dense Percoll fraction. The organelles in this fraction appeared by electron microscopy to consist mainly of acidocalcisomes (acidic calcium storage organelles). This identification was confirmed by x-ray microanalysis. Immunofluorescence and immunoelectron microscopy indicated that the V-H+-PPase was located in the plasma membrane and acidocalcisomes of the three different forms of the parasite. Pyrophosphate was able to drive calcium uptake in permeabilized T. cruzi. This uptake depended upon a proton gradient and was reversed by a specific V-H+-PPase inhibitor. Our results imply that the phylogenetic distribution of V-H+-PPases is much wider than previously perceived but that the enzyme has a unique subcellular location in trypanosomes.

Composition, Preservation and Production Technology of Augusta Emerita Roman Glasses from the First to the Sixth Century a.d.

NASA Astrophysics Data System (ADS)

Palomar, Teresa; Garcia-Heras, Manuel; Sabio, Rafael; Rincon, Jesus-Maria; Villegas, Maria-Angeles

This paper presents the results derived from an archaeometric study undertaken on glass samples from the Roman town of Augusta Emerita (Mérida, Spain). The main goal of the research was to provide for the first time some compositional and technological insights into the glass finds unearthed in this town. Glass samples from different sites and chronology, either from inside or from outside the perimeter of the ancient town and from the first to the sixth century AD, were analyzed and characterized through optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDS), X-ray fluorescence (XRF) spectrometry and VIS spectrophotometry. Resulting data indicated that all the samples studied were natron-based soda lime silicate glasses, even though two chronological and compositionally distinct groups were distinguished. One composed of Early Empire glasses and a second one composed of glasses from the fourth century AD onward, which was characterized by the presence of the so-called HIMT (high iron, manganese, and titanium) glasses. Comparison with coeval glasses suggested that Augusta Emerita shared the same trade glass circles than other contemporary Roman towns, within the frame of a secondary production scale. Finally, some outstanding differences connected to composition and chronology were found, since Late Roman glasses presented a higher and distinct degree of alteration than Early Empire ones.

Types and analysis of defects in welding junctions of the header to steam generator shells on power-generating units with VVER-1000

NASA Astrophysics Data System (ADS)

Ozhigov, L. S.; Voevodin, V. N.; Mitrofanov, A. S.; Vasilenko, R. L.

2016-10-01

Investigation objects were metal templates, which were cut during the repair of welding junction no. 111 (header to the steam generator shell) on a power-generating unit with VVER-1000 of the South-Ukraine NPP, and substances of mud depositions collected from walls of this junction. Investigations were carried out using metallography, optical microscopy, and scanning electron microscopy with energy dispersion microanalysis by an MMO-1600-AT metallurgical microscope and a JEOL JSM-7001F scanning electron microscope with the Shottky cathode. As a result of investigations in corrosion pits and mud depositions in the area of welding junction no. 111, iron and copper-enriched particles were revealed. It is shown that, when contacting with the steel header surface, these particles can form microgalvanic cells causing reactions of iron dissolution and the pit corrosion of metal. Nearby corrosion pits in metal are microcracks, which can be effect of the stress state of metal under corrosion pits along with revealed effects of twinning. The hypothesis is expressed that pitting corrosion of metal occurred during the first operation period of the power-generating unit in the ammonia water chemistry conditions (WCC). The formation of corrosion pits and nucleating cracks from them was stopped with the further operation under morpholine WCC. The absence of macrocracks in metal of templates verifies that, during operation, welding junction no. 111 operated under load conditions not exceeding the permissible ones by design requirements. The durability of the welding junction of the header to the steam generator shell significantly depends on the technological schedule of chemical cleaning and steam generator shut-down cooling.

X-ray elemental mapping techniques for elucidating the ecophysiology of hyperaccumulator plants.

PubMed

van der Ent, Antony; Przybyłowicz, Wojciech J; de Jonge, Martin D; Harris, Hugh H; Ryan, Chris G; Tylko, Grzegorz; Paterson, David J; Barnabas, Alban D; Kopittke, Peter M; Mesjasz-Przybyłowicz, Jolanta

2018-04-01

Contents Summary 432 I. Introduction 433 II. Preparation of plant samples for X-ray micro-analysis 433 III. X-ray elemental mapping techniques 438 IV. X-ray data analysis 442 V. Case studies 443 VI. Conclusions 446 Acknowledgements 449 Author contributions 449 References 449 SUMMARY: Hyperaccumulators are attractive models for studying metal(loid) homeostasis, and probing the spatial distribution and coordination chemistry of metal(loid)s in their tissues is important for advancing our understanding of their ecophysiology. X-ray elemental mapping techniques are unique in providing in situ information, and with appropriate sample preparation offer results true to biological conditions of the living plant. The common platform of these techniques is a reliance on characteristic X-rays of elements present in a sample, excited either by electrons (scanning/transmission electron microscopy), protons (proton-induced X-ray emission) or X-rays (X-ray fluorescence microscopy). Elucidating the cellular and tissue-level distribution of metal(loid)s is inherently challenging and accurate X-ray analysis places strict demands on sample collection, preparation and analytical conditions, to avoid elemental redistribution, chemical modification or ultrastructural alterations. We compare the merits and limitations of the individual techniques, and focus on the optimal field of applications for inferring ecophysiological processes in hyperaccumulator plants. X-ray elemental mapping techniques can play a key role in answering questions at every level of metal(loid) homeostasis in plants, from the rhizosphere interface, to uptake pathways in the roots and shoots. Further improvements in technological capabilities offer exciting perspectives for the study of hyperaccumulator plants into the future. © 2017 University of Queensland. New Phytologist © 2017 New Phytologist Trust.

Extraction of Ni (II) from Spent Hydrodesulfurization HDS Catalyst Through Leaching and Electroless Precipitation of Ni(OH)2

NASA Astrophysics Data System (ADS)

Pradhan, Sangita R.; Dash, Barsha; Sanjay, Kali; Subbaiah, T.

2013-04-01

The extraction of nickel (II) from a spent hydro-desulfurization catalyst containing 11.6 pct Ni was carried out through sulfuric acid leaching. Variations of parameters such as the concentration of acid, temperature, and time, were studied and optimized. Nickel hydroxide was precipitated from the leach liquor via neutralization with 1 M sodium hydroxide up to pH 12 in three different methods: normal neutralization precipitation, and then neutralization precipitation followed by aging at 353 K (80 °C) for 4 hours and neutralization of the leach liquor with 10 pct (v/v) of 0.1 N sodium lauryl sulfate. X-ray diffraction (XRD) and transmission electron microscopy (TEM) microanalysis shows a difference in crystallinity with the method of precipitation. The nickel hydroxide contains Cu(II), Co(II), Zn(II), and Mn(II) as trace impurities. The discharge capacities of the precipitated nickel hydroxides were 120 mAhg-1, 140.72 mAhg-1, and 145.2 mAhg-1 for aged sample, sample without surfactant, and with surfactant respectively.

Chemically prepared La2Se3 nanocubes thin film for supercapacitor application.

PubMed

Patil, S J; Lokhande, V C; Chodankar, N R; Lokhande, C D

2016-05-01

Lanthanum selenide (La2Se3) nanocubes thin film is prepared via successive ionic layer adsorption and reaction (SILAR) method and utilized for energy storage application. The prepared La2Se3 thin film is characterized by X-ray diffraction, field emission scanning electron microscopy and contact angle measurement techniques for structural, surface morphological and wettability studies, respectively. Energy dispersive X-ray microanalysis (EDAX) is performed in order to obtain the elemental composition of the thin film. The La2Se3 film electrode shows a maximum specific capacitance of 363 F g(-1) in a 0.8 M LiClO4/PC electrolyte at a scan rate of 5 mV s(-1) within 1.3 V/SCE potential range. The specific capacitive retention of 83 % of La2Se3 film electrode is obtained over 1000 cyclic voltammetry cycles. The predominant performance, such as high energy (80 Wh kg(-1)) and power density (2.5 kW kg(-1)), indicates that La2Se3 film electrode facilitates fast ion diffusion during redox processes. Copyright © 2016 Elsevier Inc. All rights reserved.

Composition, morphology and surface recombination rate of HCl-isopropanol treated and vacuum annealed InAs(1 1 1)A surfaces

NASA Astrophysics Data System (ADS)

Kesler, V. G.; Seleznev, V. A.; Kovchavtsev, A. P.; Guzev, A. A.

2010-05-01

X-ray photoelectron spectroscopy and atomic force microscopy were used to examine the chemical composition and surface morphology of InAs(1 1 1)A surface chemically etched in isopropanol-hydrochloric acid solution (HCl-iPA) and subsequently annealed in vacuum in the temperature range 200-500 °C. Etching for 2-30 min resulted in the formation of "pits" and "hillocks" on the sample surface, respectively 1-2 nm deep and high, with lateral dimensions 50-100 nm. The observed local formations, whose density was up to 3 × 10 8 cm -2, entirely vanished from the surface after the samples were vacuum-annealed at temperatures above 300 °C. Using a direct method, electron beam microanalysis, we have determined that the defects of the hillock type includes oxygen and excessive As, while the "pits" proved to be identical in their chemical composition to InAs. Vacuum anneals were found to cause a decrease in As surface concentration relative to In on InAs surface, with a concomitant rise of surface recombination rate.

Characterization of Morphology and Composition of Inorganic Fillers in Dental Alginates

PubMed Central

Guiraldo, Ricardo Danil; Berger, Sandrine Bittencourt; Consani, Rafael Leonardo Xediek; Consani, Simonides; de Carvalho, Rodrigo Varella; Lopes, Murilo Baena; Meneghel, Luciana Lira; da Silva, Fabiane Borges; Sinhoreti, Mário Alexandre Coelho

2014-01-01

Energy dispersive X-ray spectroscopy microanalysis (EDX), scanning electron microscopy (SEM), and Archimedes' Principle were used to determine the characteristics of inorganic filler particles in five dental alginates, including Cavex ColorChange (C), Hydrogum 5 (H5), Hydrogum (H), Orthoprint (O), and Jeltrate Plus (JP). The different alginate powders (0.5 mg) were fixed on plastic stubs (n = 5) and sputter coated with carbon for EDX analysis, then coated with gold, and observed using SEM. Volume fractions were determined by weighing a sample of each material in water before and after calcining at 450°C for 3 h. The alginate materials were mainly composed of silicon (Si) by weight (C—81.59%, H—79.89%, O—78.87%, H5—77.95%, JP—66.88%, wt). The filler fractions in volume (vt) were as follows: H5—84.85%, JP—74.76%, H—70.03%, O—68.31%, and C—56.10%. The tested materials demonstrated important differences in the inorganic elemental composition, filler fraction, and particle morphology. PMID:25165690

RADIOACTIVITY DOSAGE OF ORNAMENTAL GRANITIC ROCKS BASED ON CHEMICAL, MINERALOGICAL AND LITHOLOGICAL DATA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salas, H.T.; Nalini, H.A. Jr.; Mendes, J.C.

2004-10-03

One hundred samples of granitic rock were collected from granite traders in Belo Horizonte. Autoradiography, optical microscopy, diffractometry, and chemical analysis (X-ray spectrometry, X-ray fluorescence, neutron activation, gravimetry and electron probe microanalysis) were used to determine the mineral assemblages and lithotypes. Autoradiographic results for several samples showed the presence of monazite, allanite and zircon. Chemical analysis revealed concentrations of uranium of {le} 30ppm, and thorium {le} 130ppm. Higher concentrations generally correlated with high concentrations of light rare earths in silica-rich rocks of granitic composition. Calculations were made of radioactive doses for floor tiles in a standard room for samples withmore » total concentration of uranium and thorium greater than 60ppm. On the basis of calculations of {sup 232}Th, {sup 40}K and {sup 226}Ra from Th, K and U analysis, the doses calculated were between 0.11 and 0.34 mSv/year, which are much lower than the acceptable international exposure standard of 1.0 mSv/year.« less

[Health impact of indoor mineral particle pollution].

PubMed

Vincent, M; Chemarin, C

2011-04-01

Mineral particle air pollution consists of both atmospheric pollution and indoor pollution. Indoor pollution comes from household products, cosmetics, combustion used to heat homes or cook food, smoking, hobbies or odd jobs. There is strong evidence that acute respiratory infections in children and chronic obstructive pulmonary disease in women are associated with indoor biomass smoke. Detailed questioning is essential to identify at risk activities and sampling of airborne particles may help with the identification of pollution risks. Particle elimination depends on the standard of ventilation of the indoor environment. Five per cent of French homes have levels of pollution greater than 180 μg/m³ for PM 10 and 2% for PM 2.5. The principal mineral particle air pollutants are probably silica, talc, asbestos and carbon, whereas tobacco smoke leads to exposure to various ultrafine particles. The toxicity of these particles could be more related to surface exchange than to density. Tissue measurements by electron microscopy and microanalysis of particle samples may identify an uptake of particles similar to those in the environmental sample. Copyright © 2011. Published by Elsevier Masson SAS.

Internal iron biomineralization in Imperata cylindrica, a perennial grass: chemical composition, speciation and plant localization.

PubMed

Rodríguez, N; Menéndez, N; Tornero, J; Amils, R; de la Fuente, V

2005-03-01

* The analysis of metal distribution in Imperata cylindrica, a perennial grass isolated from the banks of Tinto River (Iberian Pyritic Belt), an extreme acidic environment with high content in metals, has shown a remarkable accumulation of iron. This property has been used to study iron speciation and its distribution among different tissues and structures of the plant. * Mossbauer (MS) and X-ray diffraction (XRD) were used to determine the iron species, scanning electron microscopy (SEM) to locate iron biominerals among plant tissue structures, and energy-dispersive X-ray microanalysis (EDAX), X-ray fluorescence (TXRF) and inductively coupled plasma emission spectroscopy (ICP-MS) to confirm their elemental composition. * The MS spectral analysis indicated that iron accumulated in this plant mainly as jarosite and ferritin. The presence of jarosite was confirmed by XRD and the distribution of both minerals in structures of different tissues was ascertained by SEM-EDAX analysis. * The convergent results obtained by complementary techniques suggest a complex iron management system in I. cylindrica, probably as a consequence of the environmental conditions of its habitat.

Metallurgical characterization of experimental Ag-based soldering alloys.

PubMed

Ntasi, Argyro; Al Jabbari, Youssef S; Silikas, Nick; Al Taweel, Sara M; Zinelis, Spiros

2014-10-01

To characterize microstructure, hardness and thermal properties of experimental Ag-based soldering alloys for dental applications. Ag12Ga (AgGa) and Ag10Ga5Sn (AgGaSn) were fabricated by induction melting. Six samples were prepared for each alloy and microstructure, hardness and their melting range were determined by, scanning electron microscopy, energy dispersive X-ray (EDX) microanalysis, X-ray diffraction (XRD), Vickers hardness testing and differential scanning calorimetry (DSC). Both alloys demonstrated a gross dendritic microstructure while according to XRD results both materials consisted predominately of a Ag-rich face centered cubic phase The hardness of AgGa (61 ± 2) was statistically lower than that of AgGaSn (84 ± 2) while the alloys tested showed similar melting range of 627-762 °C for AgGa and 631-756 °C for AgGaSn. The experimental alloys tested demonstrated similar microstructures and melting ranges. Ga and Sn might be used as alternative to Cu and Zn to modify the selected properties of Ag based soldering alloys.

Metallurgical characterization of experimental Ag-based soldering alloys

PubMed Central

Ntasi, Argyro; Al Jabbari, Youssef S.; Silikas, Nick; Al Taweel, Sara M.; Zinelis, Spiros

2014-01-01

Aim To characterize microstructure, hardness and thermal properties of experimental Ag-based soldering alloys for dental applications. Materials and methods Ag12Ga (AgGa) and Ag10Ga5Sn (AgGaSn) were fabricated by induction melting. Six samples were prepared for each alloy and microstructure, hardness and their melting range were determined by, scanning electron microscopy, energy dispersive X-ray (EDX) microanalysis, X-ray diffraction (XRD), Vickers hardness testing and differential scanning calorimetry (DSC). Results Both alloys demonstrated a gross dendritic microstructure while according to XRD results both materials consisted predominately of a Ag-rich face centered cubic phase The hardness of AgGa (61 ± 2) was statistically lower than that of AgGaSn (84 ± 2) while the alloys tested showed similar melting range of 627–762 °C for AgGa and 631–756 °C for AgGaSn. Conclusion The experimental alloys tested demonstrated similar microstructures and melting ranges. Ga and Sn might be used as alternative to Cu and Zn to modify the selected properties of Ag based soldering alloys. PMID:25382945

Deposition of lead and cadmium released by cigarette smoke in dental structures and resin composite.

PubMed

Takeuchi, Cristina Yoshie Garcia; Corrêa-Afonso, Alessandra Marques; Pedrazzi, Hamilton; Dinelli, Welingtom; Palma-Dibb, Regina Guenka

2011-03-01

Cigarette smoke is a significant source of cadmium, lead, and toxic elements, which are absorbed into the human organism. In this context, the aim of this study was to investigate in vitro the presence of toxic elements, cadmium, and lead deriving from cigarette smoke in the resin composite, dentine, and dental enamel. Eight cylindrical specimens were fabricated from resin composite, bovine enamel, and root dentin fragments that were wet ground and polished with abrasive paper to obtain sections with 6-mm diameter and 2-mm thickness. All specimens were exposed to the smoke of 10 cigarettes/day during 8 days. After the simulation of the cigarette smoke, the specimens were examined with scanning electron microscopy (SEM) and the energy-dispersive X-ray analysis. In the photomicrographic analysis in SEM, no morphological alterations were found; however, the microanalysis identified the presence of cadmium, arsenic, and lead in the different specimens. These findings suggest that the deposition of these elements derived from cigarette smoke could be favored by dental structures and resin composite. Copyright © 2010 Wiley-Liss, Inc.

Formulation and dissolution kinetics study of hydrophilic matrix tablets with tramadol hydrochloride and different co-processed dry binders.

PubMed

Komersová, Alena; Lochař, Václav; Myslíková, Kateřina; Mužíková, Jitka; Bartoš, Martin

2016-12-01

The aim of this study is to present the possibility of using of co-processed dry binders for formulation of matrix tablets with drug controlled release. Hydrophilic matrix tablets with tramadol hydrochloride, hypromellose and different co-processed dry binders were prepared by direct compression method. Hypromelloses Methocel™ K4M Premium CR or Methocel™ K100M Premium CR were used as controlled release agents and Prosolv® SMCC 90 or Disintequik™ MCC 25 were used as co-processed dry binders. Homogeneity of the tablets was evaluated using scanning electron microscopy and energy dispersive X-ray microanalysis. The release of tramadol hydrochloride from prepared formulations was studied by dissolution test method. The dissolution profiles obtained were evaluated by non-linear regression analysis, release rate constants and other kinetic parameters were determined. It was found that matrix tablets based on Prosolv® SMCC 90 and Methocel™ Premium CR cannot control the tramadol release effectively for >12h and tablets containing Disintequik™ MCC 25 and Methocel™ Premium CR >8h. Copyright © 2016 Elsevier B.V. All rights reserved.

HA/nylon 6,6 porous scaffolds fabricated by salt-leaching/solvent casting technique: effect of nano-sized filler content on scaffold properties

PubMed Central

Mehrabanian, Mehran; Nasr-Esfahani, Mojtaba

2011-01-01

Nanohydroxyapatite (n-HA)/nylon 6,6 composite scaffolds were produced by means of the salt-leaching/solvent casting technique. NaCl with a distinct range size was used with the aim of optimizing the pore network. Composite powders with different n-HA contents (40%, 60%) for scaffold fabrication were synthesized and tested. The composite scaffolds thus obtained were characterized for their microstructure, mechanical stability and strength, and bioactivity. The microstructure of the composite scaffolds possessed a well-developed interconnected porosity with approximate optimal pore size ranging from 200 to 500 μm, ideal for bone regeneration and vascularization. The mechanical properties of the composite scaffolds were evaluated by compressive strength and modulus tests, and the results confirmed their similarity to cortical bone. To characterize bioactivity, the composite scaffolds were immersed in simulated body fluid for different lengths of time and results monitored by scanning electron microscopy and energy dispersive X-ray microanalysis to determine formation of an apatite layer on the scaffold surface. PMID:21904455

Naturally Occurring Asbestos in the Southern Nevada Region: Potential for Human Exposure

NASA Astrophysics Data System (ADS)

Buck, B. J.; Metcalf, R. V.; Berry, D.; McLaurin, B.; Kent, D.; Januch, J.; Goossens, D.

2015-12-01

Naturally occurring fibrous actinolite, winchite, magnesioriebeckite, richterite, magnesiohornblende, and erionite have been found in rock, soil, and dust in southern Nevada and northwestern Arizona. The areas containing naturally occurring asbestos (NOA) include urban areas (e.g. Boulder City) and rural areas where people routinely enjoy outdoor activities including horseback riding, running, hiking, bicycling, and off-road-vehicle (ORV) recreation. A recent study showing mesothelioma in young people and women suggests some form of environmental exposure. Rock, soil, dust and clothing were analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS); additional rock samples were analyzed using wavelength dispersive electron probe microanalysis (EPMA); additional soil samples were analyzed using PLM (polarizing light microscopy) and TEM (transmission electron microscopy) using the Fluidized Bed Asbestos Segregator preparation method. Winds have transported and mixed the Ca-amphiboles, which are primarily from Nevada, with the Na-amphiboles that are primarily from northwestern Arizona. Erionite, which has not previously been reported in this area, was a common soil component found in 5 of 6 samples. The erionite source has not yet been determined. Winds have transported the amphibole and erionite particles into the Nellis Dunes Recreation Area - an ORV recreation area located 35 km north of Boulder City that otherwise would not be geologically predicted to contain fibrous amphiboles. In Boulder City, wind directions are primarily bimodal N-NE and S-SW with the strongest winds in the spring coming from the S-SW. The arid climate in this part of the Mojave Desert greatly increases the potential for wind erosion and human exposures. These results suggest that the entire Las Vegas Basin has, at times, received these particles through wind transport. Because the most likely human exposure pathway is through inhalation of dust, the Las Vegas metropolitan area, with over 1.9 million people, may be subject to exposure.

On the nature of the Fe-bearing particles influencing hard anodizing behavior of AA 7075 extrusion products

NASA Astrophysics Data System (ADS)

Mukhopadhyay, A. K.

1998-03-01

The deleterious effects of Fe-bearing constituent particles on the fracture toughness of wrought A1 alloys have been known. Recent studies have shown that the presence of Fe-bearing, constituent particles is also determental to the nature and growth of the hard anodic oxide coating formed on such materials. The present study, using a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA), was made to examine the influence of the nature of the Fe-bearing particles on the hard anodizing behavior of AA 7075 extrusion products containing varying amounts of Si, Mn, and Fe impurities. It was found that, in the alloy containing 0.25 wt pct Si, 0.27 wt pct Mn, and 0.25 wt pct Fe, the Fe-bearing constituent particles are based on the Al12(FeMn)3Si phase (bcc with α=1.260 nm). These particles survive the hard anodizing treatment, add resistance to the electrical path, causing a rapid rise in the bath voltage with time, and cause a nonuniform growth of the anodic oxide film. In the materials containing 0.05 wt pct Si, 0.04 wt pct Mn, and 0.18 wt pct Fe, on the other hand, the formation of the Al12(FeMn)3Si-based phase is suppressed, and two different Fe-bearing phases, based on Al-Fe-Cu-Mn-based (simple cubic with a=1.265 nm) and Al7Cu2Fe, respectively form. Neither the Al-Fe-Cu-Mn-based phase nor the Al7Cu2Fe-based phase survive the hard anodizing treatment, and this results in a steady rise in the bath voltage with time and a relatively uniform growth of the anodic oxide film. Consideration of the size of the Fe-bearing, particles reveals that the smaller the particle, the more uniform the growth of the anodic oxide film.

Electron microprobe analysis program for biological specimens: BIOMAP

NASA Technical Reports Server (NTRS)

Edwards, B. F.

1972-01-01

BIOMAP is a Univac 1108 compatible program which facilitates the electron probe microanalysis of biological specimens. Input data are X-ray intensity data from biological samples, the X-ray intensity and composition data from a standard sample and the electron probe operating parameters. Outputs are estimates of the weight percentages of the analyzed elements, the distribution of these estimates for sets of red blood cells and the probabilities for correlation between elemental concentrations. An optional feature statistically estimates the X-ray intensity and residual background of a principal standard relative to a series of standards.

Speciation of individual mineral particles of micrometer size by the combined use of attenuated total reflectance-Fourier transform-infrared imaging and quantitative energy-dispersive electron probe X-ray microanalysis techniques.

PubMed

Jung, Hae-Jin; Malek, Md Abdul; Ryu, JiYeon; Kim, BoWha; Song, Young-Chul; Kim, HyeKyeong; Ro, Chul-Un

2010-07-15

Our previous work demonstrated for the first time the potential of the combined use of two techniques, attenuated total reflectance FT-IR (ATR-FT-IR) imaging and a quantitative energy-dispersive electron probe X-ray microanalysis, low-Z particle EPMA, for the characterization of individual aerosol particles. In this work, the speciation of mineral particles was performed on a single particle level for 24 mineral samples, including kaolinite, montmorillonite, vermiculite, talc, quartz, feldspar, calcite, gypsum, and apatite, by the combined use of ATR-FT-IR imaging and low-Z particle EPMA techniques. These two single particle analytical techniques provide complementary information, the ATR-FT-IR imaging on mineral types and low-Z particle EPMA on the morphology and elemental concentrations, on the same individual particles. This work demonstrates that the combined use of the two single particle analytical techniques can powerfully characterize externally heterogeneous mineral particle samples in detail and has great potential for the characterization of airborne mineral dust particles.

Attenuated total reflectance FT-IR imaging and quantitative energy dispersive-electron probe X-ray microanalysis techniques for single particle analysis of atmospheric aerosol particles.

PubMed

Ryu, JiYeon; Ro, Chul-Un

2009-08-15

This work demonstrates the practical applicability of the combined use of attenuated total reflectance (ATR) FT-IR imaging and low-Z particle electron probe X-ray microanalysis (EPMA) techniques for the characterization of individual aerosol particles. These two single particle analytical techniques provide complementary information on the physicochemical characteristics of the same individual particles, that is, the low-Z particle EPMA for the information on the morphology and elemental concentration and the ATR-FT-IR imaging on the functional group, molecular species, and crystal structure. It was confirmed that the ATR-FT-IR imaging technique can provide sufficient FT-IR absorption signals to perform molecular speciation of individual particles of micrometer size when applied to artificially generated aerosol particles such as ascorbic acid and NaNO(3) aerosols. An exemplar indoor atmospheric aerosol sample was investigated to demonstrate the practical feasibility of the combined application of ATR-FT-IR imaging and low-Z particle EPMA techniques for the characterization of individual airborne particles.

Quantification of ionic transport within thermally-activated batteries using electron probe micro-analysis

DOE PAGES

Humplik, Thomas; Stirrup, Emily K.; Grillet, Anne M.; ...

2016-04-30

The transient transport of electrolytes in thermally-activated batteries is studied in this paper using electron probe micro-analysis (EPMA), demonstrating the robust capability of EPMA as a useful tool for studying and quantifying mass transport within porous materials, particularly in difficult environments where classical flow measurements are challenging. By tracking the mobility of bromine and potassium ions from the electrolyte stored within the separator into the lithium silicon anode and iron disulfide cathode, we are able to quantify the transport mechanisms and physical properties of the electrodes including permeability and tortuosity. Due to the micron to submicron scale porous structure ofmore » the initially dry anode, a fast capillary pressure driven flow is observed into the anode from which we are able to set a lower bound on the permeability of 10 -1 mDarcy. The transport into the cathode is diffusion-limited because the cathode originally contained some electrolyte before activation. Finally, using a transient one-dimensional diffusion model, we estimate the tortuosity of the cathode electrode to be 2.8 ± 0.8.« less

Study of Solid-State Diffusion of Bi in Polycrystalline Sn Using Electron Probe Microanalysis

NASA Astrophysics Data System (ADS)

Delhaise, André M.; Perovic, Doug D.

2018-03-01

Current lead-free solders such as SAC305 exhibit degradation in microstructure, properties, and reliability. Current third-generation alloys containing bismuth (Bi) demonstrate preservation of strength after aging; this is accompanied by homogenization of the Bi precipitates in the tin (Sn) matrix, driven via solid-state diffusion. This study quantifies the diffusion of Bi in Sn. Diffusion couples were prepared by mating together polished samples of pure Sn and Bi. Couples were annealed at one of three temperatures, viz. 85°C for 7 days, 100°C for 2 days, or 125°C for 1 day. After cross-sectioning the couples to examine the diffusion microstructure and grain size, elemental analysis was performed using electron probe microanalysis. For this study, it was assumed that the diffusivity of Bi in Sn is concentration dependent, therefore inverse methods were used to solve Fick's non-steady-state diffusion equation. In addition, Darken analysis was used to extract the impurity diffusivity of Bi in Sn at each temperature, allowing estimation of the Arrhenius parameters D 0 and k A.

Experimental study of the Ca-Mg-Zn system using diffusion couples and key alloys

NASA Astrophysics Data System (ADS)

Zhang, Yi-Nan; Kevorkov, Dmytro; Bridier, Florent; Medraj, Mamoun

2011-03-01

Nine diffusion couples and 32 key samples were prepared to map the phase diagram of the Ca-Mg-Zn system. Phase relations and solubility limits were determined for binary and ternary compounds using scanning electron microscopy, electron probe microanalysis and x-ray diffraction (XRD). The crystal structure of the ternary compounds was studied by XRD and electron backscatter diffraction. Four ternary intermetallic (IM) compounds were identified in this system: Ca3MgxZn15-x (4.6<=x<=12 at 335 °C, IM1), Ca14.5Mg15.8Zn69.7 (IM2), Ca2Mg5Zn13 (IM3) and Ca1.5Mg55.3Zn43.2 (IM4). Three binary compounds were found to have extended solid solubility into ternary systems: CaZn11, CaZn13 and Mg2Ca form substitutional solid solutions where Mg substitutes for Zn atoms in the first two compounds, and Zn substitutes for both Ca and Mg atoms in Mg2Ca. The isothermal section of the Ca-Mg-Zn phase diagram at 335 °C was constructed on the basis of the obtained experimental results. The morphologies of the diffusion couples in the Ca-Mg-Zn phase diagram at 335 °C were studied. Depending on the terminal compositions of the diffusion couples, the two-phase regions in the diffusion zone have either a tooth-like morphology or contain a matrix phase with isolated and/or dendritic precipitates.

Characterisation of inorganic microparticles in pigment cells of human gut associated lymphoid tissue.

PubMed Central

Powell, J J; Ainley, C C; Harvey, R S; Mason, I M; Kendall, M D; Sankey, E A; Dhillon, A P; Thompson, R P

1996-01-01

Macrophages at the base of human gut associated lymphoid tissue (GALT), become loaded early in life with dark granular pigment that is rich in aluminium, silicon, and titanium. The molecular characteristics, intracellular distribution, and source of this pigment is described. Laser scanning and electron microscopy showed that pigmented macrophages were often closely related to collagen fibres and plasma cells in GALT of both small and large intestine and contained numerous phagolysosomes, previously described as granules, that are rich in electron dense submicron sized particles. Morphological assessment, x ray microanalysis, and image electron energy loss spectroscopy showed three distinct types of microparticle: type I - spheres of titanium dioxide, 100-200 nm diameter, characterised as the synthetic food-additive polymorph anatase; type II - aluminosilicates, < 100-400 nm in length, generally of flaky appearance, often with adsorbed surface iron, and mostly characteristic of the natural clay mineral kaolinite; and type III - mixed environmental silicates without aluminium, 100-700 nm in length and of variable morphology. Thus, this cellular pigment that is partly derived from food additives and partly from the environment is composed of inert inorganic microparticles and loaded into phagolysosomes of macrophages within the GALT of all human subjects. These observations suggest that the pathogenicity of this pigment should be further investigated since, in susceptible individuals, the same intracellular distribution of these three types of submicron particle causes chronic latent granulomatous inflammation. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 PMID:8675092

Effects of copper and arsenic stress on the development of Norway spruce somatic embryos and their visualization with the environmental scanning electron microscope.

PubMed

Đorđević, Biljana; Neděla, Vilém; Tihlaříková, Eva; Trojan, Václav; Havel, Ladislav

2018-05-18

Somatic embryogenesis is an important biotechnological technique which can be used in studies associated with environmental stress. Four embryogenic cell lines of Norway spruce were grown on media enriched with copper and arsenic in concentration ranges 50-500 μM and 10-50 μM, respectively. The effects were observed during subsequent stages of somatic embryogenesis, the characteristics evaluated being proliferation potential, average number of somatic embryos obtained per g/fresh weight, morphology of developed somatic embryos, metal uptake, and microanalysis of macro- and micronutrients uptake. Copper and arsenic at higher concentrations significantly reduced the growth of early somatic embryos. In almost all treatments, the cell line V-1-3 showed the best performance compared with the other lines tested. Environmental scanning electron microscopy was used to visualize and identify morphological abnormalities in the development of somatic embryos. Abnormalities observed were classified into several categories: meristemless somatic embryos, somatic embryos with disrupted meristem, reduced number of cotyledons, single cotyledon and fused cotyledons. With the application of a low temperature method for the environmental scanning electron microscope, samples were stabilized and whole meristems could be investigated in their native state. As far as we are aware, this is the first report of the effect of copper and arsenic during the process of somatic embryogenesis and the first to evaluate the content of macro and micronutrients uptake in Norway spruce. Copyright © 2018 Elsevier B.V. All rights reserved.

New electrocatalysts for unitized regenerative fuel cell: Pt-Ir alloy deposited on the proton exchange membrane surface by impregnation-reduction method.

PubMed

Wan, Chieh-Hao; Wu, Chun-Lin; Lin, Meng-Tsun; Shih, Chihhsiong

2010-07-01

In this paper, a modified technique to prepare Pt-Ir catalyst layer on the proton exchange membrane (PEM) surface using the impregnation-reduction (IR) method is proposed to improve the electrocatalytic activity as well as the life cycle of the bifunctional oxygen electrode (BOE). The resulted electrocatalysts were characterized by the Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Electron Probe Micro-Analysis (EPMA), and Transmission Electron Microscope (TEM). The electrocatalytic properties of the Pt-Ir layer on PEM surface for the oxygen reduction and water oxidation reactions as well as the life cycle of MEA were investigated. Experimental results showed that the Ir particles were dispersed densely in the platinum layer through the modified IR technique. The atomic ratio of Pt over Ir elements was 9:1, and the resulted thickness of the obtained Pt-Ir catalyst layer was about 1.0 microm. The Pt-Ir catalyst layer was composed of Pt layer doped with Ir nano-particles comprising nano Pt-Ir alloy phase. The large surface area of Ir core with Pt shell particles and the presence of nano Pt-Ir alloy phase led to a higher electrocatalytic activity of BOE. Due to the good binding between the Nafion membrane and the Pt-Ir alloy catalyst, as well as the composite structure of the resulted Pt-Ir, the life cycle of Unitized Regenerative Fuel Cell (URFC) is improved through this novel BOE.

Archaeometric study of black-coated pottery from Pompeii by different analytical techniques.

PubMed

Scarpelli, Roberta; Clark, Robin J H; De Francesco, Anna Maria

2014-01-01

Complementary spectroscopic methods were used to characterize ceramic body and black coating of fine pottery found at Pompeii (Italy). This has enabled us to investigate local productions and to clarify the technological changes over the 4th-1st centuries BC. Two different groups of ceramics were originally distinguished on the basis of macroscopic observations. Optical microscopy (OM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) seem to indicate the usage of the same raw materials for the production of black-coated ceramics at Pompeii for about three centuries. Raman microscopy (RM) and micro-analysis (SEM/EDS) suggest different production treatments for both raw material processing and firing practice (duration of the reducing step and the cooling rate). Copyright © 2013 Elsevier B.V. All rights reserved.

Backscattering and absorption coefficients for electrons: Solutions of invariant embedding transport equations using a method of convergence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Figueroa, C.; Brizuela, H.; Heluani, S. P.

2014-05-21

The backscattering coefficient is a magnitude whose measurement is fundamental for the characterization of materials with techniques that make use of particle beams and particularly when performing microanalysis. In this work, we report the results of an analytic method to calculate the backscattering and absorption coefficients of electrons in similar conditions to those of electron probe microanalysis. Starting on a five level states ladder model in 3D, we deduced a set of integro-differential coupled equations of the coefficients with a method know as invariant embedding. By means of a procedure proposed by authors, called method of convergence, two types ofmore » approximate solutions for the set of equations, namely complete and simple solutions, can be obtained. Although the simple solutions were initially proposed as auxiliary forms to solve higher rank equations, they turned out to be also useful for the estimation of the aforementioned coefficients. In previous reports, we have presented results obtained with the complete solutions. In this paper, we present results obtained with the simple solutions of the coefficients, which exhibit a good degree of fit with the experimental data. Both the model and the calculation method presented here can be generalized to other techniques that make use of different sorts of particle beams.« less

Effect of Isovalent Substitution on the Electronic Structure and Thermoelectric Properties of the Solid Solution α-As2Te3-xSex (0 ≤ x ≤ 1.5).

PubMed

Vaney, Jean-Baptiste; Delaizir, Gaëlle; Wiendlocha, Bartlomiej; Tobola, Janusz; Alleno, Eric; Piarristeguy, Andrea; Gonçalves, Antonio Pereira; Gendarme, Christine; Malaman, Bernard; Dauscher, Anne; Candolfi, Christophe; Lenoir, Bertrand

2017-02-20

We report on the influence of Se substitution on the electronic band structure and thermoelectric properties (5-523 K) of the solid solution α-As 2 Te 3-x Se x (0 ≤ x ≤ 1.5). All of the polycrystalline compounds α-As 2 Te 3-x Se x crystallize isostructurally in the monoclinic space group C2/m (No. 12, Z = 4). Regardless of the Se content, chemical analyses performed by scanning electron microscopy and electron probe microanalysis indicate a good chemical homogeneity, with only minute amounts of secondary phases for some compositions. In agreement with electronic band structure calculations, neutron powder diffraction suggests that Se does not randomly substitute for Te but exhibits a site preference. These theoretical calculations further predict a monotonic increase in the band gap energy with the Se content, which is confirmed experimentally by absorption spectroscopy measurements. Increasing x up to x = 1.5 leaves unchanged both the p-type character and semiconducting nature of α-As 2 Te 3 . The electrical resistivity and thermopower gradually increase with x as a result of the progressive increase in the band gap energy. Despite the fact that α-As 2 Te 3 exhibits very low lattice thermal conductivity κ L , the substitution of Se for Te further lowers κ L to 0.35 W m -1 K -1 at 300 K. The compositional dependence of the lattice thermal conductivity closely follows classical models of phonon alloy scattering, indicating that this decrease is due to enhanced point-defect scattering.

A cheap protocol for colour measure and for diagnostic in planning a cultural heritage restoration. Case study: main façade of Palazzo Governi (Cagliari, Sardinia, Italy).

PubMed

Sammartino, M P; Genova, C; Ronca, S; Cau, G; Visco, G

2017-06-01

Due to the bad state of conservation, "Palazzo Governi", a seventeenth-century building located in the old town district of "Stampace" in Cagliari (Sardinia, Italy), was subjected to restoration. Thus, according to the Italian Law n. 1089, the main façade colour must be reproduced, and therefore, its identification was required. The available samples looked fairly degraded, in particular as an easy plaster to crumble; so, some other analyses able to identify the degradation cause were performed. Two different approaches were adopted to attain the first goal, the visual colour assessment by a sensory panel (subjective) and the instrumental measurement by colorimetry (objective). Ion chromatography and inductively coupled plasma-optical emission spectroscopy analyses, as well as conductivity and pH measurements, were performed to evaluate the presence of water-soluble salts inside the plaster, as possible cause of degradation; the binder/aggregate ratio was also evaluated. A full mineralogical and petrographic characterisation of the materials constituting the samples, as well as the identification of their stratigraphy and some other morphologic and structural features suitable to highlight eventual forms of degradation, were performed by optical microscopy. Scanning electron microscopy coupled to X-ray microanalysis was been also used in order to confirm and/or to integrate data obtained by optical microscopy. The samples have been compared with two samples coming from two other buildings, also located in Sardinia, that looked in good conservation state. The results evidenced that the causes of degradation come from a high salt (especially sulphate) content and a scarce presence of binder in the plaster that can be imputed to a wrong initial composition and/ or to a leaching by acidic rain.

A multi-analytical study of the fifteenth century mural paintings of the Batalha Monastery (Portugal) in view of their conservation

NASA Astrophysics Data System (ADS)

Valadas, S.; Candeias, A.; Dias, C.; Schiavon, N.; Cotovio, M.; Pestana, J.; Gil, M.; Mirão, J.

2013-12-01

The systematic characterization of the painting's palette and technique applied on the execution of the mural paintings of the Batalha Monastery (Batalha, Leiria, Portugal) is presented. These are the oldest mural paintings known in Portugal (apart from Roman frescoes) and represent the beginning of an artistic Portuguese tradition that continues until the nineteenth century. The aim of the study was to identify for the first time by adopting a multi-analytical physico-chemical approach of the pigments, binder, and alteration products (white veils, crusts, and pigment alteration) of these unique works of arts in order not only to better understand the painting technique, but also to support a conservation-restoration intervention that took place from April to August 2010. Micro-sampling of paint layers was performed on representative areas of the paintings. The characterization of the pigments and binders was carried out by microscopy and microanalysis of cross sections using optical microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM-EDS), micro-FTIR, and micro X-ray diffraction. The combined analysis of the paintings allowed the identification of the painting's palette: Vermillion (HgS) and red ochre for the reds, yellow ochres for the yellows, green earths and malachite for the greens, azurite for the blues, and carbon for the blacks. The use of the pigment is dependent of the motive painted while the most expensive materials were used in the most important iconographic motives. Alteration of malachite was identified in darkened layers in green areas of the paintings. White veil areas on the surface of the paintings were identified as calcite from precipitation/dissolution processes due to water run-off on the sacristy dome ceiling and walls.

Elemental Composition of the Powder Particles Produced by Electric Discharge Dispersion of the Wastes of a VK8 Hard Alloy

NASA Astrophysics Data System (ADS)

Latypov, R. A.; Ageev, E. V.; Latypova, G. R.; Altukhov, A. Yu.; Ageeva, E. V.

2017-12-01

The powder fabricated by electric discharge dispersion of the wastes of a VK8 hard alloy is studied by electron-probe microanalysis. This powder formed by electric discharge dispersion in kerosene mainly contains tungsten and carbon and has low contents of oxygen, cobalt, and iron.

From HeLa cell division to infectious diarrhoea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stephen, J.; Osborne, M.P.; Spencer, A.J.

1990-09-01

Hela S3 cells were grown in suspension both randomly and, synchronously using hydroxyurea which blocks cells at the G1/S interface. Cryosections were prepared, freeze-dried and analyzed by X-ray microanalysis. As cells moved into S and through M phases (Na) and (Cl) increased; both returned to normal levels upon re-entering G1 phase. The Na/K ratio was 1:1 in G1 phase. Infection of HeLa S3 cells in G1 phase with vaccinia virus resulted in no change in intracellular (Na). Infection of neonatal mice with murine rotavirus was localized to villus tip enterocytes and gave rise to diarrhoea which was maximal at 72hmore » post-infection (p.i.). Diarrhoea was preceded by ischemia of villi (18-42h p.i.) and villus shortening (maximal at 42h p.i.), and was also coincident with a dramatic regrowth of villi. At 48h p.i. a proliferative zone of electron lucent cells was observed in villus base regions. Cryosections of infected gut, taken before, during, and after infection, together with corresponding age-matched controls, were freeze-dried and analysed by X-ray microanalysis. At 48h p.i. electron lucent villus base cells were shown to be more hydrated, and, to contain higher levels of both Na and Cl and lower levels of P, S, K and Mg than corresponding control cells. These studies increase confidence in the use of X-ray microanalysis in studying biological systems, provide some insight into the process of cell division, and constitute the basis of a new concept of diarrhoeal secretion.27 references.« less

[Reparative Osteogenesis and Angiogenesis in Low Intensity Electromagnetic Radiation of Ultra-High Frequency].

PubMed

Iryanov, Y M; Kiryanov, N A

2015-01-01

Non-drug correction of reparative bone tissue regeneration in different pathological states - one of the most actual problems of modern medicine. Our aim was to conduct morphological analysis of the influence of electromagnetic radiation of ultra-high frequency and low intensity on reparative osteogenesis and angiogenesis in fracture treatment under transosseous osteosynthesis. A controlled nonrandomized study was carried out. In the experiment conducted on rats we modeled tibial fracture with reposition and fixation of the bone fragments both in control and experimental groups. In the animals of the experimental group the fracture zone was exposed to low intensity electromagnetic radiation of ultra-high frequency. Exposure simulation was performed in the control group. The operated bones were examined using radiography, light and electronic microscopy, X-ray electronic probe microanalysis. It has been established that electromagnetic radiation of ultra-high frequency sessions in fracture treatment stimulate secretory activity and degranulation of mast cells, produce microcirculatory bed vascular permeability increase, endotheliocyte migration phenotype expression, provide endovascular endothelial outgrowth formation, activate reparative osteogenesis and angiogenesis while fracture reparation becomes the one of the primary type. The full periosteal, intermediary and intraosteal bone union was defined in 28 days. Among the therapeutic benefits of electromagnetic radiation of ultra-high frequency in fracture treatment we can detect mast cell secretorv activity stimulation and endovascular anziozenesis activation.

Interdiffusion, Intrinsic Diffusion, Atomic Mobility, and Vacancy Wind Effect in γ(bcc) Uranium-Molybdenum Alloy

NASA Astrophysics Data System (ADS)

Huang, Ke; Keiser, Dennis D.; Sohn, Yongho

2013-02-01

U-Mo alloys are being developed as low enrichment uranium fuels under the Reduced Enrichment for Research and Test Reactor (RERTR) Program. In order to understand the fundamental diffusion behavior of this system, solid-to-solid pure U vs Mo diffusion couples were assembled and annealed at 923 K, 973 K, 1073 K, 1173 K, and 1273 K (650 °C, 700 °C, 800 °C, 900 °C, and 1000 °C) for various times. The interdiffusion microstructures and concentration profiles were examined via scanning electron microscopy and electron probe microanalysis, respectively. As the Mo concentration increased from 2 to 26 at. pct, the interdiffusion coefficient decreased, while the activation energy increased. A Kirkendall marker plane was clearly identified in each diffusion couple and utilized to determine intrinsic diffusion coefficients. Uranium intrinsically diffused 5-10 times faster than Mo. Molar excess Gibbs free energy of U-Mo alloy was applied to calculate the thermodynamic factor using ideal, regular, and subregular solution models. Based on the intrinsic diffusion coefficients and thermodynamic factors, Manning's formalism was used to calculate the tracer diffusion coefficients, atomic mobilities, and vacancy wind parameters of U and Mo at the marker composition. The tracer diffusion coefficients and atomic mobilities of U were about five times larger than those of Mo, and the vacancy wind effect increased the intrinsic flux of U by approximately 30 pct.

Reactions in the Tuyere Zone of Ironmaking Blast Furnace

NASA Astrophysics Data System (ADS)

Ma, Xiaodong; Zhu, Jinming; Xu, Haifa; Wang, Geoff; Lee, Hae-Geon; Zhao, Baojun

2018-02-01

A series of slags can be formed in the lower part of the ironmaking blast furnace that play important roles in smooth furnace operation, and in determining iron quality and productivity. The final slag tapped from the BF has been investigated extensively as it can be collected directly. Unfortunately, difficulties in accessing the interiors of the blast furnace limit the full understanding of other slags such as primary and bosh slags. In this study, different types of samples directly obtained from the tuyere zone of the blast furnace have been systematically analyzed and characterized using scanning electron microscopy (SEM), electron probe X-ray microanalysis (EPMA), and X-ray fluorescence (XRF), with focus on the characteristics of slags formed in the tuyere level. The samples were identified into three groups according to their morphological, mineralogical, and chemical properties: (1) tuyere slags originating from the reactions between ash and dripping slags; (2) bosh slags in the CaO-SiO2-Al2O3-MgO-FeO system, with a CaO/SiO2 weight ratio of around 1.50, and Al2O3 and MgO concentrations close to those of final slags; and (3) coke ash that did not react with bosh slags. These findings will provide useful information on the evaluation of slags inside the blast furnace and the reactions in the tuyere zone.

Copper Oxide Nanoparticle Foliar Uptake, Phytotoxicity, and Consequences for Sustainable Urban Agriculture.

PubMed

Xiong, TianTian; Dumat, Camille; Dappe, Vincent; Vezin, Hervé; Schreck, Eva; Shahid, Muhammad; Pierart, Antoine; Sobanska, Sophie

2017-05-02

Throughout the world, urban agriculture supplies fresh local vegetables to city populations. However, the increasing anthropogenic uses of metal-containing nanoparticles (NPs) such as CuO-NPs in urban areas may contaminate vegetables through foliar uptake. This study focused on the CuO-NP transfer processes in leafy edible vegetables (i.e., lettuce and cabbage) to assess their potential phytotoxicity. Vegetables were exposed via leaves for 5, 10, or 15 days to various concentrations of CuO-NPs (0, 10, or 250 mg per plant). Biomass and gas exchange values were determined in relation to the Cu uptake rate, localization, and Cu speciation within the plant tissues. High foliar Cu uptake occurred after exposure for 15 days for lettuce [3773 mg (kg of dry weight) -1 ] and cabbage [4448 mg (kg of dry weight) -1 ], along with (i) decreased plant weight, net photosynthesis level, and water content and (ii) necrotic Cu-rich areas near deformed stomata containing CuO-NPs observed by scanning electron microscopy and energy dispersive X-ray microanalysis. Analysis of the CuO-NP transfer rate (7.8-242 μg day -1 ), translocation of Cu from leaves to roots and Cu speciation biotransformation in leaf tissues using electron paramagnetic resonance, suggests the involvement of plant Cu regulation processes. Finally, a potential health risk associated with consumption of vegetables contaminated with CuO-NPs was highlighted.

Behavior of New Zealand Ironsand During Iron Ore Sintering

NASA Astrophysics Data System (ADS)

Wang, Zhe; Pinson, David; Chew, Sheng; Rogers, Harold; Monaghan, Brian J.; Pownceby, Mark I.; Webster, Nathan A. S.; Zhang, Guangqing

2016-02-01

A New Zealand ironsand sample was characterized by scanning electron microscopy (SEM), X-ray fluorescence spectroscopy, qualitative and quantitative X-ray diffraction, and electron probe microanalysis. The titanomagnetite-rich ironsand was added into an industrial sinter blend in the proportion of 5 wt pct, and the mixture was uniaxially pressed into cylindrical tablets and sintered in a tube furnace under flowing gas with various oxygen potentials and temperatures to develop knowledge and understanding of the behavior of titanium during sintering. An industrial sinter with the addition of 3 wt pct ironsand was also examined. Both the laboratory and industrial sinters were characterized by optical and SEM. Various morphologies of relict ironsand particles were present in the industrial sinter due to the heterogeneity of sintering conditions, which could be well simulated by the bench-scale sintering experiments. The assimilation of ironsand during sintering in a reducing atmosphere started with the diffusion of calcium into the lattice of the ironsand matrix, and a reaction zone was formed near the boundary within individual ironsand particles where a perovskite phase was generated. With increasing sintering temperature, in a reducing atmosphere, ironsand particles underwent further assimilation and most of the titanium moved from the ironsand particles into a glass phase. In comparison, more titanium remained in the original ironsand particles when sintered in air. Ironsand particles are more resistant to assimilation in an oxidizing atmosphere.

Microstructure Evolution and Rapid Solidification Behavior of Blended Nickel-Based Superalloy Powders Fabricated by Laser Powder Deposition

NASA Astrophysics Data System (ADS)

Tian, Y.; Gauvin, R.; Brochu, M.

2016-07-01

Laser powder deposition was performed on a substrate of Inconel 738 using blended powders of Mar M247 and Amdry DF3 with a ratio of 4:1 for repairing purposes. In the as-deposited condition, continuous secondary phases composed of γ-Ni3B eutectics and discrete (Cr, W)B borides were observed in inter-dendritic regions, and time-dependent nucleation simulation results confirmed that (Cr, W)B was the primary secondary phase formed during rapid solidification. Supersaturated solid solution of B was detected in the γ solid solution dendritic cores. The Kurz-Giovanola-Trivedi model was performed to predict the interfacial morphology and correlate the solidification front velocity (SFV) with dendrite tip radius. It was observed from high-resolution scanning electron microscopy that the dendrite tip radius of the upper region was in the range of 15 to 30 nm, which yielded a SFV of approx 30 cm/s. The continuous growth model for solute trapping behavior developed by Aziz and Kaplan was used to determine that the effective partition coefficient of B was approximately 0.025. Finally, the feasibility of the modeling results were rationalized with the Clyne-Kurz segregation simulation of B, where Clyne-Kurz prediction using a partition coefficient of 0.025 was in good agreement with the electron probe microanalysis results.

Ellipsometric porosimetry on pore-controlled TiO2 layers

NASA Astrophysics Data System (ADS)

Rosu, Dana-Maria; Ortel, Erik; Hodoroaba, Vasile-Dan; Kraehnert, Ralph; Hertwig, Andreas

2017-11-01

The practical performance of surface coatings in applications like catalysis, water splitting or batteries depends critically on the coating materials' porosity. Determining the porosity in a fast and non-destructive way is still an unsolved problem for industrial thin-films technology. As a contribution to calibrated, non-destructive, optical layer characterisation, we present a multi-method comparison study on porous TiO2 films deposited by sol-gel synthesis on Si wafers. The ellipsometric data were collected on a range of samples with different TiO2 layer thickness and different porosity values. These samples were produced by templated sol-gel synthesis resulting in layers with a well-defined pore size and pore density. The ellipsometry measurement data were analysed by means of a Bruggeman effective medium approximation (BEMA), with the aim to determine the mixture ratio of void and matrix material by a multi-sample analysis strategy. This analysis yielded porosities and layer thicknesses for all samples as well as the dielectric function for the matrix material. Following the idea of multi-method techniques in metrology, the data was referenced to imaging by electron microscopy (SEM) and to a new EPMA (electron probe microanalysis) porosity approach for thin film analysis. This work might lead to a better metrological understanding of optical porosimetry and also to better-qualified characterisation methods for nano-porous layer systems.

Bioactive Potential of 3D-Printed Oleo-Gum-Resin Disks: B. papyrifera, C. myrrha, and S. benzoin Loading Nanooxides—TiO2, P25, Cu2O, and MoO3

PubMed Central

Tebcherani, Sergio Mazurek; Kubaski, Evaldo Toniolo; de Almeida Vieira, Rogério

2017-01-01

This experimental study investigates the bioactive potential of filaments produced via hot melt extrusion (HME) and intended for fused deposition modeling (FDM) 3D printing purposes. The oleo-gum-resins from benzoin, myrrha, and olibanum in pure state and also charged with 10% of metal oxide nanoparticles, TiO2, P25, Cu2O, and MoO3, were characterized by ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray microanalysis (EDXMA), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Disks were 3D-printed into model geometries (10 × 5 mm) and the disk-diffusion methodology was used for the evaluation of antimicrobial and antifungal activity of materials in study against the clinical isolates: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. Due to their intrinsic properties, disks containing resins in pure state mostly prevent surface-associated growth; meanwhile, disks loaded with 10% oxides prevent planktonic growth of microorganisms in the susceptibility assay. The microscopy analysis showed that part of nanoparticles was encapsulated by the biopolymeric matrix of resins, in most cases remaining disorderly dispersed over the surface of resins. Thermal analysis shows that plant resins have peculiar characteristics, with a thermal behavior similar to commercial available semicrystalline polymers, although their structure consists of a mix of organic compounds. PMID:28811751

Design and performance of a Near Ultra High Vacuum Helium Ion Microscope

NASA Astrophysics Data System (ADS)

Poelsema, Bene; van Gastel, Raoul; Hlawacek, Gregor; Zandvliet, Harold J. W.

2012-02-01

The advent of He Ion Microscopy (HIM) as a new nanoscopic technique to image materials has enabled a new look at materials that is based on the interaction of swift light ions with matter. Initial HIM instruments have demonstrated high-resolution imaging, combined with great surface sensitivity, the ability to neutralize charge very efficiently, and with enhanced materials contrast when ion induced secondary electrons are used for imaging. To achieve ultimate performance, the chamber vacuum of the existing platform may be improved. For instance, carbon deposits due to beam interaction are readily seen due to the surface sensitivity of the technique. At high current densities the sharply focused beam may very efficiently decompose residual hydrocarbons. Not only can this obscure a clear view of the sample, thereby negating the benefits of the small spot size, it also limits the available acquisition time. This has proven extremely useful for nanopatterning for sensors, and other device fabrication applications at the sub-10nm level. However, it is undesirable when the instrument is used for materials characterization. We will discuss the basic considerations that went into the design of a Near-UHV He Ion Microscope [1]. First applications that the instrument was used for will be highlighted and its impact in surface physics and other research areas that require increased imaging sensitivity will be discussed. [4pt] [1] R.van Gastel et al, Microscopy and Microanalysis 17, 928-929 (2011)

Limitations to the Measurement of Oxygen Concentrations by HRTEM Imposed by Surface Roughness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lupini, Andrew R; Chisholm, Matthew F; van Benthem, Klaus

2005-01-01

In an article published in Microscopy and Microanalysis recently (Jia et al., 2004), it was claimed that aberration-corrected high resolution transmission electron microscopy (HRTEM) allows the quantitative measurement of oxygen concentrations in ceramic materials with atomic resolution. Similar claims have recently appeared elsewhere, based on images obtained through aberration correction (Jia et al., 2003; Jia & Urban, 2004) or very high voltages (Zhang et al., 2003). Seeing oxygen columns is a significant achievement of great importance (Spence, 2003) that will doubtlessly allow some exciting new science; however, other models could provide a better explanation for some of the experimental datamore » than variations in the oxygen concentration. Quantification of the oxygen concentrations was attempted by comparing experimental images with simulations in which the fractional occupancy in individual oxygen columns was reduced. The results were interpreted as representing nonstoichiometry within the bulk and at grain boundaries. This is plausible because previous studies have shown that grain boundaries can be nonstoichiometric (Kim et al., 2001), and it is indeed possible that oxygen vacancies are present at boundaries or in the bulk. However, is this the only possible interpretation? We show that for the thicknesses considered a better match to the images is obtained using a simple model of surface damage in which atoms are removed from the surface, which would usually be interpreted as surface damage or local thickness variation (from ion milling, for example).« less

Bioactive Potential of 3D-Printed Oleo-Gum-Resin Disks: B. papyrifera, C. myrrha, and S. benzoin Loading Nanooxides-TiO2, P25, Cu2O, and MoO3.

PubMed

Horst, Diogo José; Tebcherani, Sergio Mazurek; Kubaski, Evaldo Toniolo; de Almeida Vieira, Rogério

2017-01-01

This experimental study investigates the bioactive potential of filaments produced via hot melt extrusion (HME) and intended for fused deposition modeling (FDM) 3D printing purposes. The oleo-gum-resins from benzoin, myrrha, and olibanum in pure state and also charged with 10% of metal oxide nanoparticles, TiO 2 , P25, Cu 2 O, and MoO 3 , were characterized by ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray microanalysis (EDXMA), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Disks were 3D-printed into model geometries (10 × 5 mm) and the disk-diffusion methodology was used for the evaluation of antimicrobial and antifungal activity of materials in study against the clinical isolates: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli , and Candida albicans . Due to their intrinsic properties, disks containing resins in pure state mostly prevent surface-associated growth; meanwhile, disks loaded with 10% oxides prevent planktonic growth of microorganisms in the susceptibility assay. The microscopy analysis showed that part of nanoparticles was encapsulated by the biopolymeric matrix of resins, in most cases remaining disorderly dispersed over the surface of resins. Thermal analysis shows that plant resins have peculiar characteristics, with a thermal behavior similar to commercial available semicrystalline polymers, although their structure consists of a mix of organic compounds.

Understanding Thermal Transport in Graded, Layered and Hybrid Materials

DTIC Science & Technology

2014-04-01

interfacial chemistries, including metallic and carbide layers, and; (iv) mimic the observed interface structure on a TDTR specimen by manipulating the...surface carbides , which were extracted from several different composites via acid dissolution of Cu, continued throughout the last 12 months of the...effort. The previously-reported electron probe microanalysis (EPMA) based techniques were employed to estimate the interfacial carbide layer thickness

Recycling-oriented characterization of plastic frames and printed circuit boards from mobile phones by electronic and chemical imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palmieri, Roberta; Bonifazi, Giuseppe; Serranti, Silvia, E-mail: silvia.serranti@uniroma1.it

Highlights: • A recycling oriented characterization of end-of-life mobile phones was carried out. • Characterization was developed in a zero-waste-perspective, aiming to recover all the mobile phone materials. • Plastic frames and printed circuit boards were analyzed by electronic and chemical imaging. • Suitable milling/classification strategies were set up to define specialized-pre-concentrated-streams. • The proposed approach can improve the recovery of polymers, base/precious metals, rare earths and critical raw materials. - Abstract: This study characterizes the composition of plastic frames and printed circuit boards from end-of-life mobile phones. This knowledge may help define an optimal processing strategy for using thesemore » items as potential raw materials. Correct handling of such a waste is essential for its further “sustainable” recovery, especially to maximize the extraction of base, rare and precious metals, minimizing the environmental impact of the entire process chain. A combination of electronic and chemical imaging techniques was thus examined, applied and critically evaluated in order to optimize the processing, through the identification and the topological assessment of the materials of interest and their quantitative distribution. To reach this goal, end-of-life mobile phone derived wastes have been systematically characterized adopting both “traditional” (e.g. scanning electronic microscopy combined with microanalysis and Raman spectroscopy) and innovative (e.g. hyperspectral imaging in short wave infrared field) techniques, with reference to frames and printed circuit boards. Results showed as the combination of both the approaches (i.e. traditional and classical) could dramatically improve recycling strategies set up, as well as final products recovery.« less

Characterization of size-resolved urban haze particles collected in summer and winter at Taiyuan City, China using quantitative electron probe X-ray microanalysis

NASA Astrophysics Data System (ADS)

Geng, Hong; Jin, Chun-Song; Zhang, Dong-Peng; Wang, Shu-Rong; Xu, Xiao-Tian; Wang, Xu-Ran; Zhang, Yuan; Wu, Li; Ro, Chul-Un

2017-07-01

The aim of the study is to characterize the size-resolved urban haze particles and investigate their modification in morphology and composition in summer and winter using the semi-quantitative electron probe X-ray microanalysis (EPMA) based on both scanning and transmission electron microscopies equipped with ultrathin-window energy dispersive X-ray spectrometers (SEM-EDX and TEM-EDX). The haze and non-haze particles were collected through a seven-stage May cascade impactor on Dec. 29-30, 2009 and Jan. 8-9 and July 11-14, 2010 in Taiyuan, a typical inland city in the North China Plain. Approximately 3752 atmospheric particles in the size ranges of 4-2 μm, 2-1 μm, 1-0.5 μm, and 0.5-0.25 μm in aerodynamic diameter were measured and identified according to their secondary electron or TEM images and elemental atomic concentrations calculated through a Monte Carlo simulation program. Results show that on the haze days many reacted or aged mineral dust particles were encountered, in which the sulfate-containing ones outnumbered the nitrate-containing ones in the winter samples while it was on the contrary in the summer samples, suggesting different haze formation and evolution mechanisms in summer and winter. Furthermore, in the haze events (especially in summer), many CNOS-rich particles, likely mixtures of water-soluble organic carbon with (NH4)2SO4 or NH4HSO4, were observed not only in the submicron but also in the super-micron fractions. The simultaneous observation of the fresh and aged CNOS-rich particles in the same SEM or TEM images implied that the status and components of secondary particles were complicated and changeable. The significant increase of both elemental concentration ratios of [N]/[S] and [C]/[S] in the aged ones compared to the fresh ones indicated that NH4NO3 and secondary organic matter were likely absorbed onto (NH4)2SO4 or NH4HSO4 particles and mixed with them. K-rich, Fe-rich, and heavy metal-containing particles in TEM-EDX measurement were detected more in the winter haze samples than in the summer ones, suggesting that they tend to be smaller in size and mainly derive from anthropogenic biomass burning and coal combustion. It was concluded that the combined use of SEM-EDX and TEM-EDX can identify both submicron and super-micron urban haze particles in a straightforward way and trace their modifications in size, shape, mixing state, and chemical compositions in different seasons, helping address their evolution processes and hazards on human health.

Abandoned mine slags analysis by EPMA WDS X-ray mapping

NASA Astrophysics Data System (ADS)

Guimarães, F.; Rosado, L.; Morais, C.; Candeias, A. E.; Pinto, A. P.; Mirão, J.

2010-02-01

Mining activity on the Iberian Pyritic Belt (Portugal and Spain) started before Phoenician times, became particularly intense during the Roman occupation of the Iberian Peninsula (for gold), and after the industrial revolution (for gold, copper, zinc, lead and sulphur). The commonest ore of this region is a massive polymetalic sulphide accumulation, where pyrite (FeS2) is the main mineral, with variable concentrations of chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), arsenopyrite (FeAsS2), other sulphides and sulfosalts which include minor elements like Mn, Co, Ni, Se, Cd, Sb, Te, Hg and Bi. Some of the main and minor elements of these ores are hazardous and the drainage basins of pollutant source areas often induce health concerns in the resident population. Electron probe microanalysis study followed previous optical and XRD analysis of the slags. The study focused on the identification of phases how sulphide and metallic phases are distributed within the material and infer about leachable elements during weathering. Electron probe X-ray maps show evidences of different behaviour between the elements: Ca and Zn are completely leached; iron is retained in oxyhydroxides, lead and arsenic precipitate as sulphates. Electron probe microanalysis studies are essential to understand complex materials as earth materials. Nevertheless, care is required to a correct interpretation of data and most quantitative compositional data are not trustworthy.

Hygroscopic properties of internally mixed particles composed of NaCl and water-soluble organic acids.

PubMed

Ghorai, Suman; Wang, Bingbing; Tivanski, Alexei; Laskin, Alexander

2014-02-18

Atmospheric aging of naturally emitted marine aerosol often leads to formation of internally mixed particles composed of sea salts and water-soluble organic compounds of anthropogenic origin. Mixing of sea salt and organic components has profound effects on the evolving chemical composition and hygroscopic properties of the resulted particles, which are poorly understood. Here, we have studied chemical composition and hygroscopic properties of laboratory generated NaCl particles mixed with malonic acid (MA) and glutaric acid (GA) at different molar ratios using micro-FTIR spectroscopy, atomic force microscopy, and X-ray elemental microanalysis. Hygroscopic properties of internally mixed NaCl and organic acid particles were distinctly different from pure components and varied significantly with the type and amount of organic compound present. Experimental results were in a good agreement with the AIM modeling calculations of gas/liquid/solid partitioning in studied systems. X-ray elemental microanalysis of particles showed that Cl/Na ratio decreased with increasing organic acid component in the particles with MA yielding lower ratios relative to GA. We attribute the depletion of chloride to the formation of sodium malonate and sodium glutarate salts resulted by HCl evaporation from dehydrating particles.

Preparation and microstructural characterization of TiC and Ti{sub 0.6}W{sub 0.4}/TiC{sub 0.6} composite thin films obtained by activated reactive evaporation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montes de Oca, J. A.; LePetitcorps, Y.; Manaud, J.-P.

2008-05-15

Titanium carbide-based coatings were deposited on W substrates at a high coating growth rate by activated reactive evaporation at 500 and 600 deg. C in a L560 Leybold system using propene as reactive atmosphere. The crystal structure, lattice parameter, preferred orientation, and grain size of the coatings were determined by x-ray diffraction technique using Cu K{alpha}. The analysis of the coating morphology was performed by scanning electron microscopy (SEM), and the composition of the films was analyzed by Auger electron spectroscopy and electron-probe microanalysis. Experimental results suggested that temperature was one of the most important parameters in the fabrication ofmore » stoichiometric TiC coatings. Thus, TiC coatings were obtained at 600 deg. C, whereas TiC{sub 0.6} nonstoichiometric coatings codeposited with a free Ti phase were obtained at 500 deg. C, giving rise to the formation of a composite thin film. After annealing at 1000 deg. C, the stoichiometric films remained stable, but a crack pattern was formed over the entire coating surface. In addition, Ti{sub 0.6}W{sub 0.4}/TiC{sub 0.6} composite thin coatings were obtained for the films synthesized at 500 deg. C. The formation of a Ti{sub 0.6}W{sub 0.4} ductile phase in the presence of a TiC{sub 0.6} phase was responsible to avoid the coating cracking.« less

Structural characterization of biomedical Co-Cr-Mo components produced by direct metal laser sintering.

PubMed

Barucca, G; Santecchia, E; Majni, G; Girardin, E; Bassoli, E; Denti, L; Gatto, A; Iuliano, L; Moskalewicz, T; Mengucci, P

2015-03-01

Direct metal laser sintering (DMLS) is a technique to manufacture complex functional mechanical parts from a computer-aided design (CAD) model. Usually, the mechanical components produced by this procedure show higher residual porosity and poorer mechanical properties than those obtained by conventional manufacturing techniques. In this work, a Co-Cr-Mo alloy produced by DMLS with a composition suitable for biomedical applications was submitted to hardness measurements and structural characterization. The alloy showed a hardness value remarkably higher than those commonly obtained for the same cast or wrought alloys. In order to clarify the origin of this unexpected result, the sample microstructure was investigated by X-ray diffraction (XRD), electron microscopy (SEM and TEM) and energy dispersive microanalysis (EDX). For the first time, a homogeneous microstructure comprised of an intricate network of thin ε (hcp)-lamellae distributed inside a γ (fcc) phase was observed. The ε-lamellae grown on the {111}γ planes limit the dislocation slip inside the γ (fcc) phase, causing the measured hardness increase. The results suggest possible innovative applications of the DMLS technique to the production of mechanical parts in the medical and dental fields. Copyright © 2014 Elsevier B.V. All rights reserved.

A Comparative Chemical Study of Calcium Silicate-Containing and Epoxy Resin-Based Root Canal Sealers.

PubMed

Reszka, Przemysław; Nowicka, Alicja; Lipski, Mariusz; Dura, Włodzimierz; Droździk, Agnieszka; Woźniak, Krzysztof

2016-01-01

Objective. The present study assessed the chemical elements in two novel calcium silicate-containing root canal sealers, BioRoot RCS and Well-Root ST, compared to a calcium silicate-containing root canal sealer that has been on the market for several years, MTA Fillapex, and epoxy resin-based sealer AHPlus. Material and Methods. The sealers were mixed and manipulated according to the manufacturers' instructions. Twelve cylindrical molds (inner diameter 4 mm; height 3 mm) were placed on a glass petri dish and packed with the materials. The dish was transferred to an incubator. After 72 h the molds were examined by scanning electron microscopy and energy dispersive X-ray microanalysis. Results. BioRoot RCS and Well-Root ST had high peaks of calcium, zirconium, oxygen, carbon, silicon, and chlorine. Well-Root ST also had sodium, magnesium, aluminum, and titanium peaks. MTA Fillapex and AHPlus had carbon, oxygen, calcium, titanium, and bismuth peaks. A silicon peak was also observed for MTA Fillapex, and zirconium and tungsten peaks for AHPlus. Conclusion. BioRoot RSC had the highest degree of purity. The clinical implication of metals contained in the other sealers needs to be investigated.

The characterization, mobility, and persistence of roaster-derived arsenic in soils at Giant Mine, NWT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bromstad, Mackenzie J.; Wrye, Lori A.; Jamieson, Heather E.

Approximately 20,000 tonnes of arsenic (As)-bearing emissions from roasting gold (Au)-bearing arsenopyrite ore were aerially released from 1949 to 1999 at Giant Mine, near Yellowknife, Canada. Soil samples collected within 4 km of the former roaster from sites undisturbed by mining or other human activity contain up to 7700 mg/kg total As. Total As concentrations are highest within a few cm of the surface, and particularly enriched in soil pockets on rock outcrops. Scanning electron microscopy and synchrotron microanalysis show that roaster-derived arsenic trioxide (As2O3) has persisted in shallow soils in the area. Roaster-generated maghemite and hematite are also present.more » These anthropogenic forms of As are much more common in near-surface soils than natural As-bearing minerals. Comparison of the proportions of As, Sb, and Au concentrations in outcrop soil samples and historic As2O3-rich dust captured by emission controls suggest most of the roaster-derived As in soils at Giant was likely deposited before 1964. Topographic restriction by rock outcrops and a dry, cold climate likely contribute to the persistence of As2O3 in outcrop soils.« less

Effects of thyroxine and dexamethasone on rat submandibular glands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sagulin, G.B.; Roomans, G.M.

1989-08-01

Glucocorticoids and thyroxine are known to have a marked effect on the flow rate and protein composition of rat parotid saliva in hormonally intact animals. In the present study, the effects of a one-week treatment of male rats with dexamethasone and thyroxine were studied by electron microscopy and x-ray micro-analysis, and by measurement of the flow rate and determination of the chemical composition of pilocarpine-induced submandibular saliva. Thyroxine had the most extensive effects on the submandibular gland. The acinar cells were enlarged and filled with mucus; the cellular calcium concentration was significantly increased. The flow rate of the submandibular salivamore » was significantly reduced compared with that in saline-injected control animals. Thyroxine caused an increase in the concentrations of protein, total calcium, and potassium in the saliva. Dexamethasone had no significant effects on gland ultrastructure or on the elemental composition of the acinar cells; flow rate was not affected, but the concentrations of protein, calcium, and potassium were significantly increased. The effects of dexamethasone and thyroxine on the flow rate and protein composition of pilocarpine-induced rat submandibular saliva differ from those reported earlier for rat parotid saliva after simultaneous stimulation with pilocarpine and isoproterenol.« less

Investigation of the effects of cadmium by micro analytical methods on Lycopersicon esculentum Mill. roots.

PubMed

Colak, G; Baykul, M C; Gürler, R; Catak, E; Caner, N

2014-09-01

The interactions between cadmium stress and plant nutritional elements have been investigated on complete plant or at the level of organs. This study was undertaken to contribute to the exploration of the physiological basis of cadmium phytotoxicity. We examined the changes in the nutritional element compositions of the root epidermal cells of the seedlings of Lycopersicon esculentum Mill. at the initial growth stages that is known as the most sensitive stage to the stress. Effects of cadmium stress on the seedlings of Lycopersicon esculentum Mill. were examined by EDX (Energy Dispersive X-Ray Microanalysis) assay performed with using low vacuum (∼ 24 Pascal) Scanning Electron Microscopy. In the analysis performed at the level of root epidermal cells, some of the macro- and micronutrient contents of the cells (carbon, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, and zinc levels) were found to change when the applying toxic concentrations of cadmium. There was no change in the manganese and sodium content of the epidermal cells. It was concluded that the changes in nutritional element composition of the cells can be considered as an effective parameter in explaining the physiological mechanisms of cadmium-induced growth inhibition.

Trace element mapping in Parkinsonian brain by quantitative ion beam microscopy

NASA Astrophysics Data System (ADS)

Barapatre, Nirav; Morawski, Markus; Butz, Tilman; Reinert, Tilo

2010-06-01

The role of iron in the pathogenesis of the Parkinson's disease (PD) is a current subject of research in Neurochemistry, since an abnormal increase in iron is reported in the substantia nigra (SN) of Parkinsonian patients. A severe loss of the cells containing dopamine in the SN in the PD has also drawn attention towards the function of a browny-black pigment called neuromelanin, which accumulates predominantly in these dopaminergic neurons. The neuromelanin has an ability to chelate metal ions, which, in free state, may cause considerable damage to cells by reacting with their lipid-rich membranes. However, it could also potentiate free radical production if it releases the bound metal ions. The highly sensitive and non-destructive micro-PIXE method suits best to quantify and map the trace elements in the SN. The accuracy in charge measurement for such microanalysis studies is of utmost importance for quantitative analysis. Since a Faraday cup is usually placed behind the thin biological sample to measure the charge, the primary and the secondary electrons, knocked out from the sample by traversing ion beam, hamper an exact charge determination. Hence, a new non-interceptive technique was developed for precise charge measurement and for continuous monitoring of beam current.

Impact of CCR1 silencing on the assembly of lignified secondary walls in Arabidopsis thaliana.

PubMed

Ruel, Katia; Berrio-Sierra, Jimmy; Derikvand, Mohammad Mir; Pollet, Brigitte; Thévenin, Johanne; Lapierre, Catherine; Jouanin, Lise; Joseleau, Jean-Paul

2009-01-01

A cinnamoyl-CoA reductase 1 knockout mutant in Arabidopsis thaliana was investigated for the consequences of lignin synthesis perturbation on the assembly of the cell walls. The mutant displayed a dwarf phenotype and a strong collapse of its xylem vessels corresponding to lower lignin content and a loss of lignin units of the noncondensed type. Transmission electron microscopy revealed that the transformation considerably impaired the capacity of interfascicular fibers and vascular bundles to complete the assembly of cellulose microfibrils in the S(2) layer, the S(1) layer remaining unaltered. Such disorder in cellulose was correlated with X-ray diffraction showing altered organization. Semi-quantitative immunolabeling of lignins showed that the patterns of distribution were differentially affected in interfascicular fibers and vascular bundles, pointing to the importance of noncondensed lignin structures for the assembly of a coherent secondary wall. The use of laser capture microdissection combined with the microanalysis of lignins and polysaccharides allowed these polymers to be characterized into specific cell types. Wild-type A. thaliana displayed a two-fold higher syringyl to guaiacyl ratio in interfascicular fibers compared with vascular bundles, whereas this difference was less marked in the cinnamoyl-CoA reductase 1 knockout mutant.

Low-intensity lasers, modern filling materials, and bonding systems influence on mineral metabolism of hard dental tissues

NASA Astrophysics Data System (ADS)

Kunin, Anatoly A.; Yesaulenko, I. E.; Zoibelmann, M.; Pankova, Svetlana N.; Ippolitov, Yu. A.; Oleinik, Olga I.; Popova, T. A.; Koretskaya, I. V.; Shumilovitch, Bogdan R.; Podolskaya, Elana E.

2001-10-01

One of the main reasons of low quality filling is breaking Ca-P balance in hard tissues. Our research was done with the purpose of studying the influence of low intensity lasers, diodic radiation, the newest filling and bonding systems on the processes of mineral metabolism in hard dental tissues while filling a tooth. 250 patients having caries and its compli-cations were examined and treated. Our complex research included: visual and instrumental examination, finding out the level of oral cavity hygiene, acid enamel biopsy, scanning electronic microscopy and X-ray spectrum microanalysis. Filling processes may produce a negative effect on mineral metabolism of hard dental tissues the latter is less pronounced when applying fluoride-containing filling materials with bonding systems. It has also been found that bonding dentin and enamel systems are designed for both a better filling adhesion (i.e. mechanical adhesion) and migration of useful microelements present in them by their sinking into hard dental tissues (i.e. chemical adhesion). Our research showed a positive influence of low intensity laser and diodic beams accompanying the use of modern filling and bonding systems on mineral metabolism of hard dental tissues.

Development and characterization of laser surface cladding (Ti,W)C reinforced Ni-30Cu alloy composite coating on copper

NASA Astrophysics Data System (ADS)

Yan, Hua; Zhang, Peilei; Yu, Zhishui; Li, Chonggui; Li, Ruidi

2012-07-01

To improve the wear resistance of copper components, laser surface cladding (LSC) was applied to deposit (Ti,W)C reinforced Ni-30Cu alloy composite coating on copper using a cladding interlayer of Ni-30Cu alloy by Nd:YAG laser. The microstructure and phases of the composite coating were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy dispersive microanalysis (EDX). Microhardness tester and pin-on-disc wear tester were employed to evaluate the hardness and dry-sliding wear resistance. The results show that crack-free composite coating with metallurgical bonding to the copper substrate is obtained. Phases identified in the (Ti,W)C-reinforced Ni-30Cu alloy composite layer are composed of TiWC2 reinforcements and (Ni,Cu) solid solution. TiWC2 reinforcements are distributed uniformly in the (Ni,Cu) solid solution matrix with dendritic morphology in the upper region and with particles in the mid-lower region. The microhardness and wear properties of the composite coating are improved significantly in comparison to the as-received copper substrate due to the addition of 50 wt% (Ti,W)C multicarbides.

A Comparative Chemical Study of Calcium Silicate-Containing and Epoxy Resin-Based Root Canal Sealers

PubMed Central

Reszka, Przemysław; Dura, Włodzimierz; Droździk, Agnieszka; Woźniak, Krzysztof

2016-01-01

Objective. The present study assessed the chemical elements in two novel calcium silicate-containing root canal sealers, BioRoot RCS and Well-Root ST, compared to a calcium silicate-containing root canal sealer that has been on the market for several years, MTA Fillapex, and epoxy resin-based sealer AHPlus. Material and Methods. The sealers were mixed and manipulated according to the manufacturers' instructions. Twelve cylindrical molds (inner diameter 4 mm; height 3 mm) were placed on a glass petri dish and packed with the materials. The dish was transferred to an incubator. After 72 h the molds were examined by scanning electron microscopy and energy dispersive X-ray microanalysis. Results. BioRoot RCS and Well-Root ST had high peaks of calcium, zirconium, oxygen, carbon, silicon, and chlorine. Well-Root ST also had sodium, magnesium, aluminum, and titanium peaks. MTA Fillapex and AHPlus had carbon, oxygen, calcium, titanium, and bismuth peaks. A silicon peak was also observed for MTA Fillapex, and zirconium and tungsten peaks for AHPlus. Conclusion. BioRoot RSC had the highest degree of purity. The clinical implication of metals contained in the other sealers needs to be investigated. PMID:28097154

A scientific approach to the characterisation of the painting technique of an author: the case of Raffaele Rinaldi

NASA Astrophysics Data System (ADS)

La Russa, Mauro F.; Ruffolo, Silvestro A.; Belfiore, Cristina M.; Comite, Valeria; Casoli, Antonella; Berzioli, Michela; Nava, Gianluca

2014-03-01

During the last restoration of the six paintings by Raffaele Rinaldi (1851-1916), located in the church of Maria SS. Annunziata (Marano Principato, Cosenza, Italy), made between 1890 and 1903, several scientific investigations were carried out on them. The present work aims at classifying the painting in terms of its materials and technical particularities. The goal of this study was to characterise the painting technique of the painter, its evolution and possible additions made during previous restorations. Pigments, binder media and raw materials used for the application of the ground and the paint layers were studied using electronic microscopy equipped with energy dispersive spectroscopy qualitative microanalysis (SEM-EDS), infrared spectroscopy (FTIR) and gas chromatography coupled with mass spectrometry (GC/MS). Furthermore, a complete analysis of the state of preservation of these paintings represents a scientific aid and guide for its restoration, taking into account the severe damage not exclusively due to natural decay processes. Our data can provide information about historical and stylistic background as well as advise for correct planning of the cleaning procedures. The identification of materials allowed a correct restoration.

Mechanical properties and microstructures of a magnesium alloy gas tungsten arc welded with a cadmium chloride flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Z.D.; Liu, L.M.; Shen, Y.

2008-01-15

Gas tungsten arc (GTA) welds were prepared on 5-mm thick plates of wrought magnesium AZ31B alloy, using an activated flux. The microstructural characteristics of the weld joint were investigated using optical and scanning microscopy, and the fusion zone microstructure was compared with that of the base metal. The elemental distribution was also investigated by electron probe microanalysis (EPMA). Mechanical properties were determined by standard tensile tests on small-scale specimens. The as-welded fusion zone prepared using a CdCl{sub 2} flux exhibited a larger grain size than that prepared without flux; the microstructure consisted of matrix {alpha}-Mg, eutectic {alpha}-Mg and {beta}-Al{sub 12}Mg{submore » 17}. The HAZ was observed to be slightly wider for the weld prepared with a CdCl{sub 2} flux compared to that prepared without flux; thus the tensile strength was lower for the flux-prepared weld. The fact that neither Cd nor Cl was detected in the weld seam by EPMA indicates that the CdCl{sub 2} flux has a small effect on convection in the weld pool.« less

Effects of Exogenous Gibberellic Acid3 on Iron and Manganese Plaque Amounts and Iron and Manganese Uptake in Rice

PubMed Central

Guo, Yue; Zhu, Changhua; Gan, Lijun; Ng, Denny; Xia, Kai

2015-01-01

Gibberellins (GA) regulate various components of plant development. Iron and Mn plaque result from oxiding and hydroxiding Fe and Mn, respectively, on the roots of aquatic plant species such as rice (Oryza sativa L.). In this study, we found that exogenous gibberellic acid3 (GA3) spray decreased Fe plaque, but increased Mn plaque, with applications of Kimura B nutrient solution. Similar effects from GA3, leading to reduced Fe plaque and increased Mn plaque, were also found by scanning electron microscopy and energy dispersive X-ray spectrometric microanalysis. Reduced Fe plaque was observed after applying GA3 to the groups containing added Fe2+ (17 and 42 mg•L-1) and an increasing trend was detected in Mn plaques of the Mn2+ (34 and 84 mg•L-1) added treatments. In contrast, an inhibitor of GA3, uniconazole, reversed the effects of GA3. The uptake of Fe or Mn in rice plants was enhanced after GA3 application and Fe or Mn plaque production. Strong synergetic effects of GA3 application on Fe plaque production were detected. However, no synergetic effects on Mn plaque production were detected. PMID:25710173

Biosensor based on Prussian blue nanocubes/reduced graphene oxide nanocomposite for detection of organophosphorus pesticides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Lin; Zhang, Aidong; Du, Dan

2012-07-13

We demonstrate a facile procedure to efficiently prepare Prussian blue nanocubes/reduced graphene oxide (PBNCs/rGO) nanocomposite by directly mixing Fe3+ and [Fe(CN)6]3 in the presence of GO in polyethyleneimine aqueous solution, resulting in a novel acetylcholinesterase (AChE) biosensor for detection of organophosphorus pesticides (OPs). The obtained nanocomposite was characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) microanalysis. It was clearly observed that the nanosheet has been decorated with cubic PB nanoparticles and nearly all the nanoparticles are distributed uniformly only on the surface of the reduced GO. No isolated PB nanoparticles were observed, indicatingmore » the strong interaction between PB nanocubes and the reduced GO and the formation of PBNCs/rGO nanocomposite. The obtained PBNCs/rGO based AChE biosensor make the peak potential shift negatively to 220 mV. The AChE biosensor shows rapid response and high sensitivity for detection of monocrotophos. These results suggest that the PBNCs/rGO hybrids nanocomposite exhibited high electrocatalytic activity towards the oxidation of thiocholine, which lead to the sensitive detection of OP pesticides.« less

New Insights into the adsorption of aurocyanide ion on activated carbon surface: electron microscopy analysis and computational studies using fullerene-like models.

PubMed

Yin, Chun-Yang; Ng, Man-Fai; Saunders, Martin; Goh, Bee-Min; Senanayake, Gamini; Sherwood, Ashley; Hampton, Marc

2014-07-08

Despite decades of concerted experimental studies dedicated to providing fundamental insights into the adsorption of aurocyanide ion, Au(CN)2(-), on activated carbon (AC) surface, such a mechanism is still poorly understood and remains a contentious issue. This adsorption process is an essential unit operation for extracting gold from ores using carbon-in-pulp (CIP) technology. We hereby attempt to shed more light on the subject by employing a range of transmission electron microscopy (TEM) associated techniques. Gold-based clusters on the AC surface are observed by Z-contrast scanning TEM imaging and energy-filtered TEM element mapping and are supported by X-ray microanalysis. Density functional theory (DFT) calculations are applied to investigate this adsorption process for the first time. Fullerene-like models incorporating convex, concave, or planar structure which mimic the eclectic porous structures on the AC surface are adopted. Pentagonal, hexagonal, and heptagonal arrangements of carbon rings are duly considered in the DFT study. By determining the favored adsorption sites in water environment, a general adsorption trend of Au(CN)2(-) adsorbed on AC surface is revealed whereby concave > convex ≈ planar. The results suggest a tendency for Au(CN)2(-) ion to adsorb on the carbon sheet defects or edges rather than on the basal plane. In addition, we show that the adsorption energy of Au(CN)2(-) is approximately 5 times higher than that of OH(-) in the alkaline environment (in negative ion form), compared to only about 2 times in acidic environment (in protonated form), indicating the Au extraction process is much favored in basic condition. The overall simulation results resolve certain ambiguities about the adsorption process for earlier studies. Our findings afford crucial information which could assist in enhancing our fundamental understanding of the CIP adsorption process.

The neodymium-gold phase diagram

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saccone, A.; Maccio, D.; Delfino, S.

The Nd-Au phase diagram was studied in the 0 to 100 at. pct Au composition range by differential thermal analysis (DTA), X-ray diffraction (XRD), optical microscopy (LOM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Six intermetallic phases were identified, the crystallographic structures were determined or confirmed, and the melting behavior was determined, as follows: Nd{sub 2}Au, orthorhombic oP12-Co{sub 2}Si type, peritectic decomposition at 810 C; NdAu, R.T. form, orthorhombic oP8-FeB type, H.T. forms, orthorhombic oC8-CrB type and, at a higher temperature, cubic cP2-CsCl type, melting point 1470 C; Nd{sub 3}Au{sub 4}, trigonal hR42-Pu{sub 3}Pd{sub 4} type, peritectic decompositionmore » at 1250 C; Nd{sub 17}Au{sub 36}, tetragonal tP106-Nd{sub 17}Au{sub 36} type, melting point 1170 C; Nd{sub 14}Au{sub 51}, hexagonal hP65-Gd{sub 14}Ag{sub 51} type, melting point 1210 C; and NdAu{sub 6}, monoclinic mC28-PrAu{sub 6} type, peritectic decomposition at 875 C. Four eutectic reactions were found, respectively, at 19.0 at. pct Au and 655 C, at 63.0 at. pct Au and 1080 C, at 72.0 at. pct Au and 1050 C, and, finally, at 91.0 at. pct Au and 795 C. A catatectic decomposition of the ({beta}Nd) phase, at 825 C and {approx}1 at. pct Au, was also found. The results are briefly discussed and compared to those for the other rare earth-gold (R-Au) systems. A short discussion of the general alloying behavior of the coinage metals (Cu, Ag, and Au) with the rare-earth metals is finally presented.« less

Magnesium-rich minerals in sediment and suspended particulates of South Florida water bodies: implications for turbidity.

PubMed

Harris, W G; Fisher, M M; Cao, X; Osborne, T; Ellis, L

2007-01-01

Fine sediments in shallow water bodies such as Lake Okeechobee are prone to resuspension. Predominantly inorganic "mud" sediment that covers approximately 670 km2 of the lake has been recognized as a persistent source of turbidity. The objective of this study was to determine if mineral components of sediments in Lake Okeechobee and water conveyances of the northern Everglades also occur as suspended sediment and hence constitute a potential abiotic contributor to turbidity. Sediment samples were collected from nine stations within the lake and eight locations north of Water Conservation Area 2A in the Everglades. Water samples were also collected at selected locations. The silt and clay mineralogy of sediment and suspended particles was determined using X-ray diffraction, thermogravimetry, scanning-electron microscopy, energy-dispersive X-ray elemental microanalysis, and high-resolution transmission-electron microscopy. Clay fractions of the lake sediment contained the Mg silicate minerals sepiolite and palygorskite, along with smectite, dolomite, calcite, and kaolinite. Sediment silt fractions were dominated by carbonates and/or quartz, with smaller amounts of Ca phosphates and sepiolite. Mineralogy of the mud sediment was similar to that reported for geologic phosphate deposits. This suggests that the mud sediment might have accumulated by stream transport of minerals from these deposits. Suspended solids and mud-sediment mineralogy were similar, except that smectite was more abundant in suspended solids. Everglade samples also contained Mg-rich minerals. The small size, low density, and fibrous or platy nature of the prevalent mud sediment minerals make them an abiotic, hydrodynamically sensitive source of persistent turbidity in a shallow lake. Mitigation efforts focused exclusively on P-induced biogeochemical processes do not address the origin or effects of these minerals. Ecological management issues such as turbidity control, P retention, geologic P input, and suitability of dredging are related to mud-sediment properties and provenance.

Influence of Cu-Ti thin film surface properties on antimicrobial activity and viability of living cells.

PubMed

Wojcieszak, Damian; Kaczmarek, Danuta; Antosiak, Aleksandra; Mazur, Michal; Rybak, Zbigniew; Rusak, Agnieszka; Osekowska, Malgorzata; Poniedzialek, Agata; Gamian, Andrzej; Szponar, Bogumila

2015-11-01

The paper describes properties of thin-film coatings based on copper and titanium. Thin films were prepared by co-sputtering of Cu and Ti targets in argon plasma. Deposited coatings consist of 90at.% of Cu and 10at.% of Ti. Characterization of the film was made on the basis of investigations of microstructure and physicochemical properties of the surface. Methods such as scanning electron microscopy, x-ray microanalysis, x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy, optical profilometry and wettability measurements were used to assess the properties of deposited thin films. An impact of Cu-Ti coating on the growth of selected bacteria and viability of the living cells (line L929, NCTC clone 929) was described in relation to the structure, surface state and wettability of the film. It was found that as-deposited films were amorphous. However, in such surroundings the nanocrystalline grains of 10-15nm and 25-35nm size were present. High surface active area with a roughness of 8.9nm, had an effect on receiving relatively high water contact angle value (74.1°). Such wettability may promote cell adhesion and result in an increase of the probability of copper ion transfer from the film surface into the cell. Thin films revealed bactericidal and fungicidal effects even in short term-contact. High activity of prepared films was directly related to high amount (ca. 51 %) of copper ions at 1+ state as x-ray photoelectron spectroscopy results have shown. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization of retrieved orthodontic miniscrew implants.

PubMed

Eliades, Theodore; Zinelis, Spiros; Papadopoulos, Moschos A; Eliades, George

2009-01-01

The purposes of this study were to characterize the morphologic, structural, and compositional alterations and to assess any hardness changes in used orthodontic miniscrew implants. Eleven miniscrew implants (Aarhus Anchorage System, Medicon eG, Tuttlingen, Germany) placed in 5 patients were retrieved after successful service of 3.5 to 17.5 months; none showed signs of mobility or failure. These implants, and brand-, type-, and size-matched specimens as controls, were subjected to multi-technique characterization. Optical microscopy indicated loss of gloss with variable discoloration. Scanning electron microscopy and x-ray microanalysis showed morphologic alteration of the miniscrew implant surfaces with integuments formed on the surface. The materials precipitated on the surfaces were sodium, potassium, chlorine, iron, calcium, and phosphorus from the contact of the implant with biologic fluids such as blood and exudates, forming sodium chloride, potassium chloride, and calcium-phosphorus precipitates. The composition of the implant was similar to that of a titanium alloy. X-ray microtomography analysis showed no bulk structure alterations. Vickers microhardness testing showed no increased bulk or surface hardness of the retrieved specimens compared with the controls, excluding the possibility of strain-hardening phenomena as a result of self-tapping and self-drilling placement and related loading conditions. Used titanium-alloy miniscrew implants have morphologic and surface structural alterations including adsorption of an integument that is calcified as a result of contact of the implants with biologic fluids. Randomly organized osseointegration islets on these smooth titanium-alloy miniscrew surfaces might be enhanced by the extended period of retention in alveolar bone in spite of the smooth surface and immediate loading pattern of these implants.

Effects of in-office bleaching on human enamel and dentin. Morphological and mineral changes.

PubMed

Llena, Carmen; Esteve, Irene; Forner, Leopoldo

2018-05-01

The effects of HP-based products upon dental enamel and dentin are inconclusive. To evaluate changes in micromorphology and composition of calcium (Ca) and phosphate (P) in enamel and dentin after the application of 37.5% hydrogen peroxide (HP) and 35% carbamide peroxide (CP) METHODS: Crowns of 20 human teeth were divided in two halves. One half was used as control specimen and the other as experimental specimen. The control specimens were kept in artificial saliva, and the experimental specimens were divided into four groups (n=5 each): group 1 (enamel HP for 45min); group 2 (dentin HP for 45min); group 3 (enamel CP for 90min); and group 4 (dentin CP for 90min). The morphological changes were evaluated using confocal laser scanning microscopy (CLSM), while the changes in the composition of Ca and P were assessed using environmental scanning electron microscopy combined with a microanalysis system (ESEM+EDX). The results within each group and between groups were compared using the Wilcoxon test and Mann-Whitney U-test, respectively (p<0.05). Similar morphological changes in the enamel and no changes in dentin were assessed with both products. Ca and P decreased in enamel and dentin, without significant differences between them or with respect to their control specimens (p>0.05). When bleaching products with a neutral pH are used in clinical practice, both, the concentration and the application time should be taken into account in order to avoid possible structural and mineral changes in enamel and dentin. Copyright © 2018 Elsevier GmbH. All rights reserved.

Diffusion mechanism in molten salt baths during the production of carbide coatings via thermal reactive diffusion

NASA Astrophysics Data System (ADS)

Ghadi, Aliakbar; Saghafian, Hassan; Soltanieh, Mansour; Yang, Zhi-gang

2017-12-01

The diffusion mechanism of carbide-forming elements from a molten salt bath to a substrate surface was studied in this research, with particular focus on the processes occurring in the molten bath at the time of coating. Metal, oxide, and metal-oxide baths were investigated, and the coating process was performed on H13 steel substrates. Scanning electron microscopy and electron-probe microanalysis were used to study the coated samples and the quenched salt bath. The thickness of the carbide coating layer was 6.5 ± 0.5, 5.2 ± 0.5, or 5.7 ± 0.5 μm depending on whether it was deposited in a metal, oxide, or metal-oxide bath, respectively. The phase distribution of vanadium-rich regions was 63%, 57%, and 74% of the total coating deposited in metal, oxide, and metal-oxide baths, respectively. The results obtained using the metal bath indicated that undissolved suspended metal particles deposited onto the substrate surface. Then, carbon subsequently diffused to the substrate surface and reacted with the metal particles to form the carbides. In the oxide bath, oxide powders dissolved in the bath with or without binding to the oxidative structure (Na2O) of borax; they were then reduced by aluminum and converted into metal particles. We concluded that, in the metal and oxide baths, the deposition of metal particles onto the sample surface is an important step in the formation of the coating.

Microanalysis of extended-test xenon hollow cathodes

NASA Technical Reports Server (NTRS)

Verhey, Timothy R.; Patterson, Michael J.

1991-01-01

Four hollow cathode electron sources were analyzed via boroscopy, scanning electron microscopy, energy dispersive x ray analysis, and x ray diffraction analysis. These techniques were used to develop a preliminary understanding of the chemistry of the devices that arise from contamination due to inadequate feed-system integrity and improper insert activation. Two hollow cathodes were operated in an ion thruster simulator at an emission current of 23.0 A for approximately 500 hrs. The two tests differed in propellant-feed systems, discharge power supplies, and activation procedures. Tungsten deposition and barium tungstate formation on the internal cathode surfaces occurred during the first test, which were believed to result from oxygen contamination of the propellant feed-system. Consequently, the test facility was upgraded to reduce contamination, and the test was repeated. The second hollow cathode was found to have experienced significantly less tungsten deposition. A second pair of cathodes examined were the discharge and the neutralizer hollow cathodes used in a life-test of a 30-cm ring-cusp ion thruster at a 5.5 kW power level. The cathodes' test history was documented and the post-test microanalyses are described. The most significant change resulting from the life-test was substantial tungsten deposition on the internal cathode surfaces, as well as removal of material from the insert surface. In addition, barium tungstate and molybdate were found on insert surfaces. As a result of the cathode examinations, procedures and approaches were proposed for improved discharge ignition and cathode longevity.

An expert system for chemical speciation of individual particles using low-Z particle electron probe X-ray microanalysis data.

PubMed

Ro, Chul-Un; Kim, HyeKyeong; Van Grieken, René

2004-03-01

An electron probe X-ray microanalysis (EPMA) technique, using an energy-dispersive X-ray detector with an ultrathin window, designated a low-Z particle EPMA, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements, such as C, N, and O, as well as chemical elements that can be analyzed by conventional energy-dispersive EPMA, in individual particles. Since a data set is usually composed of data for several thousands of particles in order to make environmentally meaningful observations of real atmospheric aerosol samples, the development of a method that fully extracts chemical information contained in the low-Z particle EPMA data is important. An expert system that can rapidly and reliably perform chemical speciation from the low-Z particle EPMA data is presented. This expert system tries to mimic the logic used by experts and is implemented by applying macroprogramming available in MS Excel software. Its feasibility is confirmed by applying the expert system to data for various types of standard particles and a real atmospheric aerosol sample. By applying the expert system, the time necessary for chemical speciation becomes shortened very much and detailed information on particle data can be saved and extracted later if more information is needed for further analysis.

Improved electron probe microanalysis of trace elements in quartz

USGS Publications Warehouse

Donovan, John J.; Lowers, Heather; Rusk, Brian G.

2011-01-01

Quartz occurs in a wide range of geologic environments throughout the Earth's crust. The concentration and distribution of trace elements in quartz provide information such as temperature and other physical conditions of formation. Trace element analyses with modern electron-probe microanalysis (EPMA) instruments can achieve 99% confidence detection of ~100 ppm with fairly minimal effort for many elements in samples of low to moderate average atomic number such as many common oxides and silicates. However, trace element measurements below 100 ppm in many materials are limited, not only by the precision of the background measurement, but also by the accuracy with which background levels are determined. A new "blank" correction algorithm has been developed and tested on both Cameca and JEOL instruments, which applies a quantitative correction to the emitted X-ray intensities during the iteration of the sample matrix correction based on a zero level (or known trace) abundance calibration standard. This iterated blank correction, when combined with improved background fit models, and an "aggregate" intensity calculation utilizing multiple spectrometer intensities in software for greater geometric efficiency, yields a detection limit of 2 to 3 ppm for Ti and 6 to 7 ppm for Al in quartz at 99% t-test confidence with similar levels for absolute accuracy.

The density of the cell sap and endoplasm of Nitellopsis and Chara

NASA Technical Reports Server (NTRS)

Wayne, R.; Staves, M. P.

1991-01-01

We measured the densities of the cell sap, endoplasm and cell wall of Nitellopsis obtusa and Chara corallina using interference microscopy, refractometry, immersion refractometry, equilibrium sedimentation and chemical microanalysis techniques. These values are important for the determination of many rheological properties of the cytoplasm as well as for understanding buoyancy regulation, dispersal mechanisms and how cells respond to gravity. The average densities of the cell sap, endoplasm and cell wall are 1,006.9, 1,016.7 and 1,371 kg m-3 for Nitellopsis and 1,005.0, 1,013.9, and 1,355.3 kg m-3 for Chara.

Core Community Specifications for Electron Microprobe Operating Systems: Software, Quality Control, and Data Management Issues

NASA Technical Reports Server (NTRS)

Fournelle, John; Carpenter, Paul

2006-01-01

Modem electron microprobe systems have become increasingly sophisticated. These systems utilize either UNIX or PC computer systems for measurement, automation, and data reduction. These systems have undergone major improvements in processing, storage, display, and communications, due to increased capabilities of hardware and software. Instrument specifications are typically utilized at the time of purchase and concentrate on hardware performance. The microanalysis community includes analysts, researchers, software developers, and manufacturers, who could benefit from exchange of ideas and the ultimate development of core community specifications (CCS) for hardware and software components of microprobe instrumentation and operating systems.

Identification of stainless steel welding fume particulates in human lung and environmental samples using electron probe microanalysis.

PubMed

Stettler, L E; Groth, D H; MacKay, G R

1977-02-01

Open lung biopsy specimens from two welders and air samples from their workplace environments were examined with the electron probe microanalyzer. X-ray analysis showed that the majority of particles found in the lung tissue from both workers and in the air samples to be composed of varying amounts of iron, chromium, manganese and nickel, the major components of some types of stainless steel. Based upon these analyses, it was concluded that the majority of the particles in both biopsy specimens were a result of the workplace environment.

The detection of sulphur in contamination spots in electron probe X-ray microanalysis

USGS Publications Warehouse

Adler, I.; Dwornik, E.J.; Rose, H.J.

1962-01-01

Sulphur has been identified as one of the elements present in the contamination spot which forms under the electron beam in the microprobe. The presence of the sulphur results in a rapid change in intensity measurements causing a loss of observed intensity for elements other than sulphur. The source of sulphur has been traced at least in part to the Apiezon B diffusion pump oil. A comparative X-ray fluorescence study of the Apiezon B and Octoil diffusion pump oils showed substantial amounts of sulphur in the Apiezon B. The Octoil was relatively free of sulphur.

Through-thickness recrystallization characteristics of a laminated AA3xxx–AA6xxx aluminum alloy system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liao, L.H., E-mail: l2liao@uwaterloo.ca; Jin, H.; Gallerneault, M.

2015-03-15

The through-thickness annealing behavior of a laminated AA3xxx–AA6xxx alloy system at 300 °C has been studied by scanning electron microscopy, electron backscatter diffraction analysis, electron probe micro-analysis, differential scanning calorimetry, and hardness measurement. Results show that the recrystallization process starts at the interface region between the AA3xxx (clad) and AA6xxx (core) layers. Subsequently, the recrystallization process front progresses into the core layer, while the clad layer is the last region to recrystallize. It is also found that precipitation precedes recrystallization in the entire laminate at the investigated temperature. The preferential onset of recrystallization at the interface region is attributed tomore » the net driving pressure being the highest in this region. The factors that lead to such enhanced net driving pressure are (a) deformation incompatibility between the two alloy layers, (b) lower solute content of the interface, which also leads to lower volume fraction of precipitates, and (c) an accelerated rate of precipitate coarsening due to the presence of a higher density of dislocations. The gradual progress of recrystallization from the interface towards the core layer is dictated by precipitate coarsening and the dependence of its rate on the density of deformation-induced dislocations. The lower driving pressure due to lower work hardening capacity, high solute drag pressure due to Mn, and additional Zener drag from precipitates that form due to solute redistribution during annealing explain the late initiation of recrystallization in the clad layer. - Highlights: • The through-thickness recrystallization of a laminated system is investigated. • The early onset of recrystallization at the interface is discussed. • The effects of precipitation and coarsening on recrystallization are analyzed.« less

Tunable dielectric response and electronic conductivity of potassium-ion-doped tunnel-structured manganese oxides

NASA Astrophysics Data System (ADS)

He, Gaihua; Duan, Yuping; Song, Lulu; Zhang, Xuefeng

2018-06-01

Potassium-ion-doped MnO2 has been successfully synthesized using the hydrothermal method, and the influence of the doped potassium ions on the electrical conductivity and permittivity is studied. X-ray powder diffraction, scanning electron microscopy, electron-probe micro-analysis, and a vector network analyzer are used to perform characterization. The densities of states of doped and undoped MnO2 tunnel structures are also discussed based on first-principles calculations. Results show that the conductivity and dielectric resonance of MnO2 can be elevated by means of K+ doping. The conductivity of K+-doped MnO2 prepared at different reaction times shows a decreasing trend and is generally 1 order of magnitude higher than that of pure MnO2. The electrical conductivity of K+-doped MnO2 (R3) shows the highest value of 3.33 × 10-2 S/cm at the reaction time of 24 h, while that of pure MnO2 is 8.50 × 10-4 S/cm. When treated with acid, the conductivity of samples remains basically stable along with the increase of treatment time. In addition, acid treatment plays a very significant role in controlling the amount of K+ ions in crystals. The K+ contents of acid-treated samples are 5 times lower than that of the untreated R1. The dielectric losses of the samples with different reaction times are enhanced markedly with frequency increment. The complex permittivity of pure MnO2 only exhibits a resonance at ˜12 GHz, while K+-doped MnO2 exhibits another resonance behavior at ˜9 GHz. The capacity of the dielectric property in the net structure is enhanced by the interfacial polarization, dielectric relaxation, multiple internal reflections, and multiple scattering benefiting.

Mechanisms of ultrafine-grained austenite formation under different isochronal conditions in a cold-rolled metastable stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Celada-Casero, C., E-mail: c.celada@cenim.csic.es

The primary objective of this work is to obtain fundamental insights on phase transformations, with focus on the reaustenitization process (α′→γ transformation), of a cold-rolled (CR) semi-austenitic metastable stainless steel upon different isochronal conditions (0.1, 1, 10 and 100 °C/s). For this purpose, an exhaustive microstructural characterization has been performed by using complementary experimental such as scanning and transmission electron microscopy (SEM and TEM), electron backscattered diffraction (EBSD), electron probe microanalysis (EPMA), micro-hardness Vickers and magnetization measurements. It has been detected that all microstructural changes shift to higher temperatures as the heating rate increases. The reaustenitization occurs in two-steps formore » all heating rates, which is attributed to the chemical banding present in the CR state. The α′→γ transformation is controlled by the migration of substitutional alloying elements across the austenite/martensite (γ/α′) interface, which finally leads to ultrafine-grained reaustenitized microstructures (440–280 nm). The morphology of the martensite phase in the CR state has been found to be the responsible for such a grain refinement, along with the presence of χ-phase and nanometric Ni{sub 3}(Ti,Al) precipitates that pin the austenite grain growth, especially upon slowly heating at 0.1 °C/s. - Highlights: •Ultrafine-grained austenite structures are obtained isochronally at 0.1–100 °C/s •The α′→γ transformation occurs in two steps due to the initial chemical banding •A diffusional mechanism governs the α′→γ transformation for all heating rates •The dislocation-cell-type of martensite promotes a diffusional mechanism •Precipitates located at α′/γ interfaces hinder the austenite growth.« less

Quantitative Electron Probe Microanalysis: State of the Art

NASA Technical Reports Server (NTRS)

Carpernter, P. K.

2005-01-01

Quantitative electron-probe microanalysis (EPMA) has improved due to better instrument design and X-ray correction methods. Design improvement of the electron column and X-ray spectrometer has resulted in measurement precision that exceeds analytical accuracy. Wavelength-dispersive spectrometer (WDS) have layered-dispersive diffraction crystals with improved light-element sensitivity. Newer energy-dispersive spectrometers (EDS) have Si-drift detector elements, thin window designs, and digital processing electronics with X-ray throughput approaching that of WDS Systems. Using these systems, digital X-ray mapping coupled with spectrum imaging is a powerful compositional mapping tool. Improvements in analytical accuracy are due to better X-ray correction algorithms, mass absorption coefficient data sets,and analysis method for complex geometries. ZAF algorithms have ban superceded by Phi(pz) algorithms that better model the depth distribution of primary X-ray production. Complex thin film and particle geometries are treated using Phi(pz) algorithms, end results agree well with Monte Carlo simulations. For geological materials, X-ray absorption dominates the corretions end depends on the accuracy of mass absorption coefficient (MAC) data sets. However, few MACs have been experimentally measured, and the use of fitted coefficients continues due to general success of the analytical technique. A polynomial formulation of the Bence-Albec alpha-factor technique, calibrated using Phi(pz) algorithms, is used to critically evaluate accuracy issues and can be also be used for high 2% relative and is limited by measurement precision for ideal cases, but for many elements the analytical accuracy is unproven. The EPMA technique has improved to the point where it is frequently used instead of the petrogaphic microscope for reconnaissance work. Examples of stagnant research areas are: WDS detector design characterization of calibration standards, and the need for more complete treatment of the continuum X-ray fluorescence correction.

Influence of the chemical composition of rapidly quenched amorphous alloys (Ni, Fe, Cr)-B-Si on its crystallization process

NASA Astrophysics Data System (ADS)

Elmanov, G.; Dzhumaev, P.; Ivanitskaya, E.; Skrytnyi, V.; Ruslanov, A.

2016-04-01

This paper presents results of research of the structure and phase transformations during the multistage crystallization of the metallic glasses with the compositions Ni71,5Cr6,8Fe2,7B11,9Si7,1 and Ni63,4Cr7,4Fe4,3Mn0,8B15,6Si8,5 labeled as AWS BNi-2 according to American Welding Society. Differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX) were used as experimental research methods. The influence of the alloys chemical composition (boron, manganese and iron) on the temperatures and the exothermic heat effects of phase transformations, as well as on the phase composition of alloys at three stages of crystallization was analyzed. We present a thermodynamic explanation of the observed heat effects. It has been shown that manganese has the main influence on the phase transformations temperatures and heat effects in these two alloys. It is also assumed that at the final crystallization stage simultaneously with the formation of phases Ni3B and β1-Ni3Si should occur the nucleation of borides of CrB type with high Cr and low Si content.

Effects of thermal treatments on microstructure and mechanical properties of a Co-Cr-Mo-W biomedical alloy produced by laser sintering.

PubMed

Mengucci, P; Barucca, G; Gatto, A; Bassoli, E; Denti, L; Fiori, F; Girardin, E; Bastianoni, P; Rutkowski, B; Czyrska-Filemonowicz, A

2016-07-01

Direct Metal Laser Sintering (DMLS) technology based on a layer by layer production process was used to produce a Co-Cr-Mo-W alloy specifically developed for biomedical applications. The alloy mechanical response and microstructure were investigated in the as-sintered state and after post-production thermal treatments. Roughness and hardness measurements, and tensile and flexural tests were performed to study the mechanical response of the alloy while X-ray diffraction (XRD), electron microscopy (SEM, TEM, STEM) techniques and microanalysis (EDX) were used to investigate the microstructure in different conditions. Results showed an intricate network of ε-Co (hcp) lamellae in the γ-Co (fcc) matrix responsible of the high UTS and hardness values in the as-sintered state. Thermal treatments increase volume fraction of the ε-Co (hcp) martensite but slightly modify the average size of the lamellar structure. Nevertheless, thermal treatments are capable of producing a sensible increase in UTS and hardness and a strong reduction in ductility. These latter effects were mainly attributed to the massive precipitation of an hcp Co3(Mo,W)2Si phase and the contemporary formation of Si-rich inclusions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of arsenic flow on the crystal structure of epitaxial GaAs grown at low temperatures on GaAs (100) and (111)A substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galiev, G. B.; Klimov, E. A.; Vasiliev, A. L.

The influence of arsenic flow in a growth chamber on the crystal structure of GaAs grown by molecular-beam epitaxy at a temperature of 240°C on GaAs (100) and (111)A substrates has been investigated. The flow ratio γ of arsenic As4 and gallium was varied in the range from 16 to 50. GaAs films were either undoped, or homogeneously doped with silicon, or contained three equidistantly spaced silicon δ-layers. The structural quality of the annealed samples has been investigated by transmission electron microscopy. It is established for the first time that silicon δ-layers in “low-temperature” GaAs serve as formation centers ofmore » arsenic precipitates. Their average size, concentration, and spatial distribution are estimated. The dependence of the film structural quality on γ is analyzed. Regions 100–150 nm in size have been revealed in some samples and identified (by X-ray microanalysis) as pores. It is found that, in the entire range of γ under consideration, GaAs films on (111)A substrates have a poorer structural quality and become polycrystalline beginning with a thickness of 150–200 nm.« less

Effect of cadmium on the physiological parameters and the subcellular cadmium localization in the potato (Solanum tuberosum L.).

PubMed

Xu, Dongyu; Chen, Zhifan; Sun, Ke; Yan, Dong; Kang, Mingjie; Zhao, Ye

2013-11-01

The pollution of agricultural soils with cadmium (Cd) has become a serious problem worldwide. The potato (Solanum tuberosum L.) was used to investigate how different concentrations of Cd (1, 5, and 25mgkg(-1)) affected the physiological parameters and the subcellular distribution of Cd in the potato. The analyses were conducted using scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX). The results suggest that the leaf is the organ with the highest accumulation of Cd. The malondialdehyde (MDA) content increased and the chlorophyll content decreased in response to high level of Cd. The SEM-EDX microanalysis revealed that Cd was primarily deposited in the spongy and palisade tissues of the leaf. Furthermore, Cd was also detected in the cortex and the adjacent phloem and was observed inside the intercellular space, the interior surface of the plasma membrane, and on the surface of the elliptical starch granules in the tubers of the potato. Although low concentrations of Cd migrated from the root to the tuber, the accumulation of Cd in the tuber exceeded the standard for food security. Therefore, the planting of potato plants in farmland containing Cd should be seriously evaluated because Cd-containing potatoes might present high health risk to humans. Copyright © 2013 Elsevier Inc. All rights reserved.

Sensitive, selective, disposable electrochemical dopamine sensor based on PEDOT-modified laser scribed graphene.

PubMed

Xu, Guangyuan; Jarjes, Zahraa A; Desprez, Valentin; Kilmartin, Paul A; Travas-Sejdic, Jadranka

2018-06-01

The fabrication of a novel, and highly selective electrochemical sensor based on a poly(3,4-ethylenedioxythiophene) (PEDOT) modified laser scribed graphene (LSG), and detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA) is described. LSG electrodes were produced with a 3-dimensional macro-porous network and large electrochemically-active surface area via direct laser writing on polyimide sheets. PEDOT was electrodeposited on the LSG electrode, and the physical properties of the obtained films were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray diffraction microanalysis (EDAX). The modified electrodes were applied for the determination of DA in the presence of AA and UA using cyclic voltammetry (CV), and differential pulse voltammetry (DPV) techniques. The linear range for dopamine detection was found to be 1-150 µM with a sensitivity of 0.220 ± 0.011 µA μM -1 and a detection limit of 0.33 µM; superior values to those obtained without PEDOT. For the first time, PEDOT-modified LSG have been fabricated and assessed for high-performance dopamine sensing using cost-effective, disposable electrodes, with potential for development in further sensing applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Pulsed electrodeposition for the synthesis of strontium-substituted calcium phosphate coatings with improved dissolution properties.

PubMed

Drevet, Richard; Benhayoune, Hicham

2013-10-01

Strontium-substituted calcium phosphate coatings are synthesized by pulsed electrodeposition on titanium alloy (Ti6Al4V) substrates. Experimental conditions of the process are optimized in order to obtain a coating with a 5% atomic substitution of calcium by strontium which corresponds to the best observations on the osteoblast cells activity and on the osteoclast cells proliferation. The physical and chemical characterizations of the obtained coating are carried out by scanning electron microscopy associated to energy dispersive X-ray spectroscopy (EDXS) for X-ray microanalysis and the structural characterization of the coating is carried out by X-ray diffraction. The in vitro dissolution/precipitation properties of the coated substrates are investigated by immersion into Dulbecco's Modified Eagle Medium (DMEM) from 1h to 14 days. The calcium, phosphorus and strontium concentrations variations in the biological liquid are assessed by Induced Coupled Plasma - Atomic Emission Spectroscopy for each immersion time. The results show that under specific experimental conditions, the electrodeposition process is suitable to synthesize strontium-substituted calcium phosphate coatings. Moreover, the addition of hydrogen peroxide (H2O2) into the electrolytic solution used in the process allows us to observe a control of the strontium release during the immersion of the prosthetic materials into DMEM. © 2013.

Chloride-associated adaptive response in aerobic methylotrophic dichloromethane-utilising bacteria.

PubMed

Torgonskaya, Maria L; Doronina, Nina V; Hourcade, Edith; Trotsenko, Yuri A; Vuilleumier, Stéphane

2011-06-01

Aerobic methylotrophic bacteria able to grow with dichloromethane (DCM) as the sole carbon and energy source possess a specific glutathione S-transferase, DCM dehalogenase, which transforms DCM to formaldehyde, used for biomass and energy production, and hydrochloric acid, which is excreted. Evidence is presented for chloride-specific responses for three DCM-degrading bacteria, Methylobacterium extorquens DM4, Methylopila helvetica DM6 and Albibacter methylovorans DM10. Chloride release into the medium was inhibited by sodium azide and m -chlorophenylhydrazone, suggesting an energy-dependent process. In contrast, only nigericin affected chloride excretion in Mb. extorquens DM4 and Mp. helvetica DM6, while valinomycin had the same effect in A. methylovorans DM10 only. Chloride ions stimulated DCM-dependent induction of DCM dehalogenase expression for Mp. helvetica DM6 and A. methylovorans DM10, and shortened the time for onset of chloride release into the medium. Striking chloride-containing structures were observed by electron microscopy and X-ray microanalysis on the cell surface of Mp. helvetica DM6 and A. methylovorans DM10 during growth with DCM, and with methanol in medium supplemented with sodium chloride. Taken together, these data suggest the existence of both general and specific chloride-associated adaptations in aerobic DCM-degrading bacteria. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Comparative Study on the Effect of MWCNT as Reinforcement on the Corrosion Parameters of Different Ni-W/MWCNTs Nanocomposite Coatings in Various Corrosive Media

NASA Astrophysics Data System (ADS)

Mohammadpour, Zahra; Zare, Hamid R.

2018-07-01

Nickel-tungsten multi-walled carbon nanotubes (Ni-W/MWCNTs) nanocomposite coatings were co-electrodeposited in the ammonium-free bath by means of constant direct current coulometry. The results indicate that the amount of MWCNTs incorporated into the nanocomposite coatings has a key role in the improvement of their microhardness and corrosion resistance. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy methods in three corrosive media of 3.5 wt% NaCl, 1.0 M NaOH, and 0.5 M H2SO4. The experimental data of the corrosion current density (jcorr), corrosion rate (CR), the polarization resistance (Rp), and microhardness indicate that the presence of MWCNTs in coatings improves the quality of those coatings. The surface morphology of the coatings and the elemental analysis data were obtained by scanning electron microscopy and energy dispersive X-ray microanalysis respectively. As the results showed, the coatings were uniform and crack-free in the presence of 5.3 wt% carbon. Also, a microhardness test revealed that the nanocomposite coating containing 5.3 wt% carbon obtained in an ammonium-free bath which provided the higher content of tungsten had the highest hardness value among others.

A Comparative Study on the Effect of MWCNT as Reinforcement on the Corrosion Parameters of Different Ni-W/MWCNTs Nanocomposite Coatings in Various Corrosive Media

NASA Astrophysics Data System (ADS)

Mohammadpour, Zahra; Zare, Hamid R.

2018-03-01

Nickel-tungsten multi-walled carbon nanotubes (Ni-W/MWCNTs) nanocomposite coatings were co-electrodeposited in the ammonium-free bath by means of constant direct current coulometry. The results indicate that the amount of MWCNTs incorporated into the nanocomposite coatings has a key role in the improvement of their microhardness and corrosion resistance. The corrosion behavior of the coatings was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy methods in three corrosive media of 3.5 wt% NaCl, 1.0 M NaOH, and 0.5 M H2SO4. The experimental data of the corrosion current density (jcorr), corrosion rate (CR), the polarization resistance (Rp), and microhardness indicate that the presence of MWCNTs in coatings improves the quality of those coatings. The surface morphology of the coatings and the elemental analysis data were obtained by scanning electron microscopy and energy dispersive X-ray microanalysis respectively. As the results showed, the coatings were uniform and crack-free in the presence of 5.3 wt% carbon. Also, a microhardness test revealed that the nanocomposite coating containing 5.3 wt% carbon obtained in an ammonium-free bath which provided the higher content of tungsten had the highest hardness value among others.

Irradiation experiment on ZrC-coated fuel particles for high-temperature gas-cooled reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Minato, Kazuo; Ogawa, Toru; Sawa, Kazuhiro

2000-06-01

The ZrC coating layer is a candidate to replace the SiC coating layer of the Triso-coated fuel particle. To compare the irradiation performance of the ZrC Triso-coated fuel particles with that of the normal Triso-coated fuel particles at high temperatures, a capsule irradiation experiment was performed, where both types of the coated fuel particles were irradiated under identical conditions. The burnup was 4.5% FIMA and the irradiation temperature was 1,400 to 1,650 C. The postirradiation measurement of the through-coating failure fractions of both types of coated fuel particles revealed better irradiation performance of the ZrC Triso-coated fuel particles. The opticalmore » microscopy and electron probe microanalysis on the polished cross section of the ZrC Triso-coated fuel particles revealed no interaction of palladium with the ZrC coating layer nor accumulation of palladium at the inner surface of the ZrC coating layer, whereas severe corrosion of the SiC coating layer was observed in the normal Triso-coated fuel particles. Although no corrosion of the ZrC coating layer was observed, additional evaluations need to be made of this layer's ability to satisfactorily retain the fission product palladium.« less

Protein Adsorption to Titanium and Zirconia Using a Quartz Crystal Microbalance Method

PubMed Central

Kusakawa, You

2017-01-01

Protein adsorption onto titanium (Ti) or zirconia (ZrO2) was evaluated using a 27 MHz quartz crystal microbalance (QCM). As proteins, fibronectin (Fn), a cell adhesive protein, and albumin (Alb), a cell adhesion-inhibiting protein, were evaluated. The Ti and ZrO2 sensors for QCM were characterized by atomic force microscopy and electron probe microanalysis observation, measurement of contact angle against water, and surface roughness. The amounts of Fn and Alb adsorbed onto the Ti and ZrO2 sensors and apparent reaction rate were obtained using QCM measurements. Ti sensor showed greater adsorption of Fn and Alb than the ZrO2 sensor. In addition, amount of Fn adsorbed onto the Ti or ZrO2 sensors was higher than that of Alb. The surface roughness and hydrophilicity of Ti or ZrO2 may influence the adsorption of Fn or Alb. With regard to the adsorption rate, Alb adsorbed more rapidly than Fn onto Ti. Comparing Ti and ZrO2, Alb adsorption rate to Ti was faster than that to ZrO2. Fn adsorption will be effective for cell activities, but Alb adsorption will not. QCM method could simulate in vivo Fn and Alb adsorption to Ti or ZrO2. PMID:28246591

Foliar lead uptake by lettuce exposed to atmospheric fallouts.

PubMed

Uzu, Gaëlle; Sobanska, Sophie; Sarret, Géraldine; Muñoz, Manuel; Dumat, Camille

2010-02-01

Metal uptake by plants occurs by soil-root transfer but also by direct transfer of contaminants from the atmosphere to the shoots. This second pathway may be particularly important in kitchen gardens near industrial plants. The mechanisms of foliar uptake of lead by lettuce ( Lactuca sativa ) exposed to the atmospheric fallouts of a lead-recycling plant were studied. After 43 days of exposure, the thoroughly washed leaves contained 335 +/- 50 mg Pb kg(-1) (dry weight). Micro-X-ray fluorescence mappings evidenced Pb-rich spots of a few hundreds of micrometers in diameter located in necrotic zones. These spots were more abundant at the base of the central nervure. Environmental scanning electron microscopy coupled with energy dispersive X-ray microanalysis showed that smaller particles (a few micrometers in diameter) were also present in other regions of the leaves, often located beneath the leaf surface. In addition, submicrometric particles were observed inside stomatal openings. Raman microspectrometry analyses of the leaves identified smelter-originated Pb minerals but also secondary phases likely resulting from the weathering of original particles. On the basis of these observations, several pathways for foliar lead uptake are discussed. A better understanding of these mechanisms may be of interest for risk assessment of population exposure to atmospheric metal contamination.

Biodegradation of orthodontic metallic brackets and associated implications for friction.

PubMed

Regis, Saulo; Soares, Paulo; Camargo, Elisa S; Guariza Filho, Odilon; Tanaka, Orlando; Maruo, Hiroshi

2011-10-01

This study aimed to assess the effect of clinical exposure on the surface morphology, dimensions, and frictional behavior of metallic orthodontic brackets. Ninety-five brackets, of 3 commercial brands, were retrieved from patients who had finished orthodontic treatment. As-received brackets, matched by type and brand, were used for comparisons. Surface morphology and precipitated material were analyzed by optical and scanning electron microscopy and x-ray microanalysis. Bracket dimensions were measured with a measuring microscope. Resistance to sliding on a stainless steel wire was assessed. Retrieved brackets showed surface alterations from corrosion, wear, and plastic deformation, especially in the external slot edges. Film deposition over the alloy surface was observed to a variable extent. The main elements in the film were carbon, oxygen, calcium, and phosphorus. The as-received brackets showed differences (P <0.05) in the slot sizes among brands, and 1 brand showed a 3% increase in the retrieved brackets' slots. The frictional behavior differed among brands. Retrieved brackets of 2 brands showed 10% to 20% increases in resistance to sliding. Metallic brackets undergo significant degradation during orthodontic treatment, possibly with increased friction. At present, it is difficult to predict the impact of these changes on the clinical performance of orthodontic components. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Bacterially induced mineralization of calcium carbonate: the role of exopolysaccharides and capsular polysaccharides.

PubMed

Ercole, Claudia; Cacchio, Paola; Botta, Anna Lucia; Centi, Valeria; Lepidi, Aldo

2007-02-01

Bacterially induced carbonate mineralization has been proposed as a new method for the restoration of limestones in historic buildings and monuments. We describe here the formation of calcite crystals by extracellular polymeric substances isolated from Bacillus firmus and Bacillus sphaericus. We isolated bacterial outer structures (glycocalix and parietal polymers), such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) and checked for their influence on calcite precipitation. CPS and EPS extracted from both B. firmus and B. sphaericus were able to mediate CaCO3 precipitation in vitro. X-ray microanalysis showed that in all cases the formed crystals were calcite. Scanning electron microscopy showed that the shape of the crystals depended on the fractions utilized. These results suggest the possibility that biochemical composition of CPS or EPS influences the resulting morphology of CaCO3. There were no precipitates in the blank samples. CPS and EPS comprised of proteins and glycoproteins. Positive alcian blue staining also reveals acidic polysaccharides in CPS and EPS fractions. Proteins with molecular masses of 25-40 kDa and 70 kDa in the CPS fraction were highly expressed in the presence of calcium oxalate. This high level of synthesis could be related to the binding of calcium ions and carbonate deposition.

Decomposition of Ag-based soldering alloys used in space maintainers after intra-oral exposure. A retrieval analysis study.

PubMed

Soteriou, Despo; Ntasi, Argyro; Papagiannoulis, Lisa; Eliades, Theodore; Zinelis, Spiros

2014-02-01

The aim of this study was to evaluate the elemental alterations of Ag soldering alloys used in space maintainers after intra-oral exposure. Twenty devices were fabricated by using two different soldering alloys; US (Dentaurum Universal Silver Solder, n = 10) and OS (Leone Orthodontic Solder, n = 10). All devices were manufactured by the same technician. Surface morphology and elemental quantitative analysis of the soldering alloys before and after intra-oral placement in patients was determined by scanning electron microscopy and energy-dispersive X-ray microanalysis (SEM/EDX). Statistical analysis was performed by t-test, Mann Whitney tests and Pearson's correlation. For all tests a 95% confidence level was used (α = 0.05). Both soldering alloys demonstrated substantially increase in surface roughness after intra-oral aging. Statistical analysis illustrated a significant decrease in the Cu and Zn content after treatment. OS demonstrated higher Cu release than US (p < 0.05). The remaining relative concentrations of Cu and Zn after the treatment did not show any correlation (p > 0.05) with intra-oral exposure time, apart from Zn in OS (r = 0.840, p = 0.04). Both soldering alloys demonstrated a significant Cu and Zn reduction after intra-oral exposure that may raise biocompatibility concerns.

Structural analysis of reactionary dentin formed in response to polymicrobial invasion

PubMed Central

Charadram, Nattida; Austin, Christine; Trimby, Patrick; Simonian, Mary; Swain, Michael V.; Hunter, Neil

2013-01-01

In response to microbial invasion of dentin odontoblasts secrete an altered calcified matrix termed reactionary dentin (Rd). 3D reconstruction of focused-ion-beam scanning electron microscopy (FIB-SEM) image slices revealed helical tubular structures in Rd that contrasted with regular cylindrical tubules characteristic of dentin from healthy teeth and affected so-called physiological dentin (Pd) lying exterior to Rd. This helical structure in Rd provided effective constriction of tubule lumen diameter that formed a barrier to bacterial advance towards the dental pulp. SEM of resin cast preparations revealed altered extension of odontoblast processes through Rd. The distribution of key mineral elements was studied by combination of 3D reconstruction of focused-ion-beam based X-ray microanalysis (FIB-EDS), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). There was a marked redistribution of calcium and phosphorous in Rd together with an increase of diffusely deposited magnesium compatible with the mineral deposition phase of synthesis of this altered matrix. Changes in tubule structure and mineral content characteristic of Rd are consistent with reduced hardness and lower elastic modulus reported for this matrix. Findings provide insight into the unique structure of Rd synthesised as a primary response to infection. PMID:23261402

QEMSCAN° (Quantitative Evaluation of Minerals by Scanning Electron Microscopy): capability and application to fracture characterization in geothermal systems

NASA Astrophysics Data System (ADS)

Ayling, B.; Rose, P. E.; Zemach, E.; Drakos, P. S.; Petty, S.

2011-12-01

Fractures are important conduits for fluids in geothermal systems, and the creation and maintenance of fracture permeability is a fundamental aspect of EGS (Engineered Geothermal System) development. Hydraulic or chemical stimulation techniques are often employed to achieve this. In the case of chemical stimulation, an understanding of the minerals present in the fractures themselves is desirable to better design a stimulation effort (i.e. which chemical to use and how much). Borehole televiewer surveys provide important information about regional and local stress regimes and fracture characteristics (e.g. fracture aperture), and XRD is useful for examining bulk rock mineralogy, but neither technique is able to quantify the distribution of these minerals in fractures. QEMSCAN° is a fully-automated micro-analysis system that enables quantitative chemical analysis of materials and generation of high-resolution mineral maps and images as well as porosity structure. It uses a scanning electron microscopy platform (SEM) with an electron beam source in combination with four energy-dispersive X-ray spectrometers (EDS). The measured backscattered electron and electron-induced secondary X-ray emission spectra are used to classify sample mineralogy. Initial applications of QEMSCAN° technology were predominantly in the minerals industry and application to geothermal problems has remained limited to date. In this pilot study, the potential application of QEMSCAN° technology to fracture characterization was evaluated using samples of representative mineralized fractures in two geothermal systems (Newberry Volcano, Oregon and Brady's geothermal field, Nevada). QEMSCAN° results were compared with XRD and petrographic techniques. Nine samples were analyzed from each field, collected from the drill core in the 1000-1500 m depth range in two shallow wells (GEO-N2 at Newberry Volcano and BCH-3 at Brady's). The samples were prepared as polished thin sections for QEMSCAN° analysis. Results indicate that a sampling resolution of 10 μm is sufficient to resolve fracture morphology and mineral zonation (where multiple episodes of mineralization occurred), and enables relatively fast data acquisition (3 cm2 can be analyzed in approximately 3 hours). Finer resolutions (down to 2.5 μm) take significantly longer, but can be used to provide additional spatial detail in areas of interest after a low resolution (10 μm) scan. Use of XRD data in conjunction with QEMSCAN° data is sometimes needed to distinguish geothermal alteration minerals with similar chemical compositions (clay minerals, micas and chlorite), however overall the technique appears to have excellent potential for geothermal applications.

Crystal Chemistry and Conductivity Studies in the System La 0.5+ x+ yLi 0.5-3 xTi 1-3 yCr 3 yO 3

NASA Astrophysics Data System (ADS)

Martínez-Sarrión, M. L.; Mestres, L.; Morales, M.; Herraiz, M.

2000-12-01

The stoichiometry polymorphism and electrical behavior of solid solutions La0.5+x+yLi0.5-3xTi1-3yCr3yO3 with perovskite-type structure were studied. Data are given in the form of a solid solutions triangle, phase diagrams, XRD patterns for the three polymorphs, A, β, and C, composition dependence of their lattice parameters, and ionic and electronic conductivity plots. Microstructure and composition were studied by SEM/EDS and electron probe microanalysis. These compounds are mixed conductors. Ionic conductivity decreased when the amount of lithium diminished and electronic conductivity increased with chromium content.

[Scanning electron microscope observation and image quantitative analysis of Hippocampi].

PubMed

Zhang, Z; Pu, Z; Xu, L; Xu, G; Wang, Q; Xu, G; Wu, L; Chen, J

1998-12-01

The "scale-like projects" on the derma of 3 species of Hippocampi, H. kuda Bleerer, H. trimaculatus Leach and H. japonicus Kaup were observed by scanning electron microscope (SEM). Results showed that some characteristics such us size, shape and type of arrangement of the "scale-like projects" can be considered as the evidence for microanalysis. Image quantitative analysis of the "scale-like project" was carried out on 45 pieces of photograph using area, long diameter, short diameter and shape factor as parameters. No difference among the different parts of the same species was observed, but significant differences were found among the above 3 species.

Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

NASA Technical Reports Server (NTRS)

Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

1993-01-01

An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

Calculated X-ray Intensities Using Monte Carlo Algorithms: A Comparison to Experimental EPMA Data

NASA Technical Reports Server (NTRS)

Carpenter, P. K.

2005-01-01

Monte Carlo (MC) modeling has been used extensively to simulate electron scattering and x-ray emission from complex geometries. Here are presented comparisons between MC results and experimental electron-probe microanalysis (EPMA) measurements as well as phi(rhoz) correction algorithms. Experimental EPMA measurements made on NIST SRM 481 (AgAu) and 482 (CuAu) alloys, at a range of accelerating potential and instrument take-off angles, represent a formal microanalysis data set that has been widely used to develop phi(rhoz) correction algorithms. X-ray intensity data produced by MC simulations represents an independent test of both experimental and phi(rhoz) correction algorithms. The alpha-factor method has previously been used to evaluate systematic errors in the analysis of semiconductor and silicate minerals, and is used here to compare the accuracy of experimental and MC-calculated x-ray data. X-ray intensities calculated by MC are used to generate a-factors using the certificated compositions in the CuAu binary relative to pure Cu and Au standards. MC simulations are obtained using the NIST, WinCasino, and WinXray algorithms; derived x-ray intensities have a built-in atomic number correction, and are further corrected for absorption and characteristic fluorescence using the PAP phi(rhoz) correction algorithm. The Penelope code additionally simulates both characteristic and continuum x-ray fluorescence and thus requires no further correction for use in calculating alpha-factors.

Single-particle characterization of urban aerosol particles collected in three Korean cites using low-Z electron probe X-ray microanalysis.

PubMed

Ro, Chul-Un; Kim, HyeKyeong; Oh, Keun-Young; Yea, Sun Kyung; Lee, Chong Bum; Jang, Meongdo; Van Grieken, René

2002-11-15

A recently developed single-particle analytical technique, called low-Z electron probe X-ray microanalysis (low-Z EPMA), was applied to characterize urban aerosol particles collected in three cities of Korea (Seoul, CheongJu, and ChunCheon) on single days in the winter of 1999. In this study, it is clearly demonstrated that the low-Z EPMA technique can provide detailed and quantitative information on the chemical composition of particles in the urban atmosphere. The collected aerosol particles were analyzed and classified on the basis of their chemical species. Various types of particles were identified, such as soil-derived, carbonaceous, marine-originated, and anthropogenic particles. In the sample collected in Seoul, carbonaceous, aluminosilicates, silicon dioxide, and calcium carbonate aerosol particles were abundantly encountered. In the CheongJu and ChunCheon samples, carbonaceous, aluminosilicates, reacted sea salts, and ammonium sulfate aerosol particles were often seen. However, in the CheongJu sample, ammonium sulfate particles were the most abundant in the fine fraction. Also, calcium sulfate and nitrate particles were significantly observed. In the ChunCheon sample, organic particles were the most abundant in the fine fraction. Also, sodium nitrate particles were seen at high levels. The ChunCheon sample seemed to be strongly influenced by sea-salt aerosols originating from the Yellow Sea, which is located about 115 km away from the city.

Single-particle mineralogy of Chinese soil particles by the combined use of low-Z particle electron probe X-ray microanalysis and attenuated total reflectance-FT-IR imaging techniques.

PubMed

Malek, Md Abdul; Kim, Bowha; Jung, Hae-Jin; Song, Young-Chul; Ro, Chul-Un

2011-10-15

Our previous work on the speciation of individual mineral particles of micrometer size by the combined use of attenuated total reflectance FT-IR (ATR-FT-IR) imaging and a quantitative energy-dispersive electron probe X-ray microanalysis technique (EPMA), low-Z particle EPMA, demonstrated that the combined use of these two techniques is a powerful approach for looking at the single-particle mineralogy of externally heterogeneous minerals. In this work, this analytical methodology was applied to characterize six soil samples collected at arid areas in China, in order to identify mineral types present in the samples. The six soil samples were collected from two types of soil, i.e., loess and desert soils, for which overall 665 particles were analyzed on a single particle basis. The six soil samples have different mineralogical characteristics, which were clearly differentiated in this work. As this analytical methodology provides complementary information, the ATR-FT-IR imaging on mineral types, and low-Z particle EPMA on the morphology and elemental concentrations, on the same individual particles, more detailed information can be obtained using this approach than when either low-Z particle EPMA or ATR-FT-IR imaging techniques are used alone, which has a great potential for the characterization of Asian dust and mineral dust particles. © 2011 American Chemical Society

Ultraviolet germicidal irradiation and its effects on elemental distributions in mouse embryonic fibroblast cells in x-ray fluorescence microanalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Qiaoling; Vogt, Stefan; Lai, Barry

Rapidly-frozen hydrated (cryopreserved) specimens combined with cryo-scanning x-ray fluorescence microscopy provide an ideal approach for investigating elemental distributions in biological cells and tissues. However, because cryopreservation does not deactivate potentially infectious agents associated with Risk Group 2 biological materials, one must be concerned with contamination of expensive and complicated cryogenic x-ray microscopes when working with such materials. We employed ultraviolet germicidal irradiation to decontaminate previously cryopreserved cells under liquid nitrogen, and then investigated its effects on elemental distributions under both frozen hydrated and freeze dried states with x-ray fluorescence microscopy. We show that the contents and distributions of most biologicallymore » important elements remain nearly unchanged when compared with non-ultraviolet-irradiated counterparts, even after multiple cycles of ultraviolet germicidal irradiation and cryogenic x-ray imaging. This provides a potential pathway for rendering Risk Group 2 biological materials safe for handling in multiuser cryogenic x-ray microscopes without affecting the fidelity of the results.« less

Ultraviolet germicidal irradiation and its effects on elemental distributions in mouse embryonic fibroblast cells in x-ray fluorescence microanalysis

DOE PAGES

Jin, Qiaoling; Vogt, Stefan; Lai, Barry; ...

2015-02-23

Rapidly-frozen hydrated (cryopreserved) specimens combined with cryo-scanning x-ray fluorescence microscopy provide an ideal approach for investigating elemental distributions in biological cells and tissues. However, because cryopreservation does not deactivate potentially infectious agents associated with Risk Group 2 biological materials, one must be concerned with contamination of expensive and complicated cryogenic x-ray microscopes when working with such materials. We employed ultraviolet germicidal irradiation to decontaminate previously cryopreserved cells under liquid nitrogen, and then investigated its effects on elemental distributions under both frozen hydrated and freeze dried states with x-ray fluorescence microscopy. We show that the contents and distributions of most biologicallymore » important elements remain nearly unchanged when compared with non-ultraviolet-irradiated counterparts, even after multiple cycles of ultraviolet germicidal irradiation and cryogenic x-ray imaging. This provides a potential pathway for rendering Risk Group 2 biological materials safe for handling in multiuser cryogenic x-ray microscopes without affecting the fidelity of the results.« less

A new concept in polymeric thin-film composite nanofiltration membranes with antibacterial properties.

PubMed

Mollahosseini, Arash; Rahimpour, Ahmad

2013-01-01

A new, thin film, biofouling resistant, nanofiltration (NF) membrane was fabricated with two key characteristics, viz. a low rate of silver (Ag) release and long-lasting antibacterial properties. In the new approach, nanoparticles were embedded completely in a polymeric thin-film layer. A comparison was made between the new thin-film composite (TFC), NF membrane and thin-film nanocomposite (TFN), and antibacterial NF membranes. Both types of NF membrane were fabricated by interfacial polymerization on a polysulphone sublayer using m-phenylenediamine and trimesoyl chloride as an amine monomer and an acid chloride monomer, respectively. Energy dispersive X-ray (EDX) microanalysis demonstrated the presence of Ag nanoparticles. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the cross-sectional and surface morphological properties of the NF membranes. Permeability and salt rejection were tested using a dead-end filtration cell. Ag leaching from the membranes was measured using inductively coupled mass spectrometry (ICP-MS). Morphological studies showed that the TFC NF membranes had better thin-film formation (a more compact structure and a smoother surface) than TFN NF membranes. Performance experiments on TFC NF membranes revealed that permeability was good, without sacrificing salt rejection. The antibacterial properties of the fabricated membranes were tested using the disk diffusion method and viable plate counts. The antibiofouling properties of the membranes were examined by measuring the quantity of bacterial cells released from the biofilm formed (as a function of the amount of biofilm present). A more sensitive surface was observed compared to that of a typical antibacterial NF membrane. The Ag leaching rates were low, which will likely result in long-lasting antibacterial and biofouling resistant properties.

Electron-excited energy dispersive x-ray spectrometry in the variable pressure scanning electron microscope (EDS/VPSEM): it's not microanalysis anymore!

NASA Astrophysics Data System (ADS)

Newbury, Dale E.; Ritchie, Nicholas W. M.

2015-10-01

X-ray spectra suffer significantly degraded spatial resolution when measured in the variable-pressure scanning electron microscope (VPSEM, chamber pressure 1 Pa to 2500 Pa) as compared to highvacuum SEM (operating pressure < 10 mPa). Depending on the gas path length, electrons that are scattered hundreds of micrometers outside the focused beam can contribute 90% or more of the measured spectrum. Monte Carlo electron trajectory simulation, available in NIST DTSA-II, models the gas scattering and simulates mixed composition targets, e.g., particle on substrate. The impact of gas scattering at the major (C > 0.1 mass fraction), minor (0.01 <= C <= 0.1), and trace (C < 0.01) constituent levels can be estimated. NIST DTSA-II for Java-platforms is available free at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).

Aubrite basalt vitrophyres: High sulfur silicate melts and a snapshot of aubrite formation. [Abstract only

NASA Technical Reports Server (NTRS)

Fogel, R. A.

1994-01-01

Two aubrite basalt vitrophyre clasts have been found within AMNH thin sections from the Parsa EH3 chondrite and the Khor Temiki aubrite. Polished sections of the Parsa Aubrite Inclusion (PAI) and the Khor Temiki Inclusion (KTI) were studied by optical, electron probe microanalysis (EPMA), and scanning electron microscopy (SEM) techniques with broad-beam and low absorbed EPMA currents used to minimize glass volatile loss. Some data have previously been reported for PAI and KTI may possibly correlate to a previously reported inclusion in Khor Tiimiki. In polished sections, PAI and KTI are approximately equal 4 mm in diameter and contain a large volume of glass. The clasts have similar textural characteristics and are akin to lunar vitrophyre textures. The glasses have high alkali rhyodacitic compositions Al-though PAI is peraluminous, KTI is significantly peralkaline. Additionally, the glasses have elevated sulfur concentrations that are extremely high by geochemical standards. SEM examination for beam overlap of microscopic CaS, FeS, and (Mg, Mn, Fe) S inclusions showed no such contamination. Furthermore, homogeneity of glass S content and low FeO contents help rule out contamination. Materials research data show that under reducing conditions alumino-silicate melts can dissolve up to several weight percent sulfur in the absence of Fe. The high S and alkali contents, the lack of associated high shock features, and the rationalized phase equilibria suggest that PAI and KTI are igneous melting products of an E-chondrite-like source material. Although large-scale impact melting cannot totally be ruled out, the above observations eliminate the possibility of in-situ shock melting.

Trends in analysis of gunshot residue for forensic purposes.

PubMed

Brożek-Mucha, Zuzanna

2017-10-01

Detection and identification of organic and inorganic components of gunshot residue are well established within forensic chemistry because of highly characteristic and uncommon features of the products of ammunition discharge at the time and place of a shooting incident in comparison to other materials present in daily life of people. Both types of residue play an important role in establishing various circumstances of a shooting crime, though the most vital one concerns the possibility of relating a suspect with the activity of shooting. In this aspect, solid, inorganic particles, nowadays called characteristic, have been utilized. Their specific features result from the primer mixture composition, including compounds of heavy metals, lead, antimony, and barium, and from the extraordinarily dynamic conditions of their formation, taking place at the moment of the primer detonation. Scanning electron microscopy and X-ray microanalysis techniques proved to be necessary and sufficient to reveal the content and the spherical morphology of the particles for this purpose. Recently, the recommendation that the potential for lead exposure be minimized was followed in the production of ammunition cal. 9 mm Luger, 0.40 S&W, 0.380 Auto, and 0.38 Special. These modern types of ammunition expel less characteristic particles, the identification of which can be a challenge for the examiners. At least two solutions to strengthen the residue identity are taken into account: additional insights into the internal structure of inorganic particles, e.g., by means of electron backscattered diffraction and focused ion beam, as well as complementary examinations of organic residues with sensitive mass spectrometric techniques.

Black and brown pigment gallstones differ in microstructure and microcomposition.

PubMed

Malet, P F; Takabayashi, A; Trotman, B W; Soloway, R D; Weston, N E

1984-01-01

The two subtypes of pigment gallstones, black and brown stones, differ in chemical composition and pathogenesis. We examined a black bilirubinate stone and a black phosphate stone (which represented opposite ends of the compositional spectrum of black noncarbonate stones), a black carbonate stone, and a brown pigment stone using scanning electron microscopy and microchemical techniques to determine if stone microstructure and microcomposition reflected different patterns of formation. The cross-sectional surfaces of the black bilirubinate and black phosphate stones were smooth and homogenous. Electron probe microanalysis demonstrated high concentrations of sulfur and copper in the center of the black bilirubinate stone; sulfur was in a low valence state consistent with disulfide linkages in proteins. The brown stone was rough-surfaced with lamellated bands on cross-section. The lighter-colored bands in this stone contained virtually all of the detected calcium palmitate, while the darker sections contained much more calcium bilirubinate. Plasma oxygen etching demonstrated a network of protein interdigitating with calcium bilirubinate salts in the black bilirubinate and black phosphate stones but not in the black carbonate or brown stones. Argon ion etching demonstrated that calcium bilirubinate was in a closely packed rod-shaped arrangement in all three black stones but not in the brown stone. We conclude that the marked differences in structure and composition between the black noncarbonate and brown pigment gallstones support the hypothesis that the two major pigment gallstone types form by different mechanisms. In addition, the layered structures of the black carbonate and brown stones suggest that stone growth is affected by cyclic changes in biliary composition.

High-temperature oxidation behavior and mechanism of a new type of wrought Ni-Fe-Cr-Al superalloy up to 1300 C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, J.; Fang, H.; Fu, X.

The oxidation behavior of a new type of wrought Ni-Fe-Cr-Al superalloys has been investigated systematically in the temperature range of 1,100 to 1,300 C. Results are compared with those of alloy 214, Inconel 600, and GH 3030. It is shown that the oxidation resistance of the new superalloys is excellent and much better than that of the comparison alloys. Scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and X-ray diffraction (XRD) experiments reveal that the excellent oxidation resistance of the new superalloy is due to the formation of a dense, stable and continuous Al{sub 2}O{sub 3} and Cr{sub 2}O{sub 3}more » oxide layer at high temperatures. Differential thermal analysis (DTA) shows that the formation of Cr{sub 2}O{sub 3} and Al{sub 2}O{sub 3} oxide layers on the new superalloy reaches a maximum at 1,060 and 1,356 C, respectively. The Cr{sub 2}O{sub 3} layer peels off easily, and the single dense Al{sub 2}O{sub 3} layer remains, giving good oxidation resistance at temperatures higher than 1,150 C. In addition, the new superalloy possesses high mechanical strength at high temperatures. On-site tests showed that the new superalloy has ideal oxidation resistance and can be used at high temperatures up to 1,300 C in various oxidizing and corrosion atmospheres, such as those containing SO{sub 2}, CO{sub 2} etc., for long periods.« less

Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

PubMed

Yoshinari, Masao; Uzawa, Shinobu; Komiyama, Yataro

2016-10-01

The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Microstructure and crystallographic preferred orientation of polycrystalline microgarnet aggregates developed during progressive creep, recovery, and grain boundary sliding

USGS Publications Warehouse

Massey, M.A.; Prior, D.J.; Moecher, D.P.

2011-01-01

Optical microscopy, electron probe microanalysis, and electron backscatter diffraction methods have been used to examine a broad range of garnet microstructures within a high strain zone that marks the western margin of a major transpression zone in the southern New England Appalachians. Garnet accommodated variable states of finite strain, expressed as low strain porphyroclasts (Type 1), high strain polycrystalline aggregates (Type 2), and transitional morphologies (Type 3) that range between these end members. Type 1 behaved as rigid porphyroclasts and is characterized by four concentric Ca growth zones. Type 2 help define foliation and lineation, are characterized by three Ca zones, and possess a consistent bulk crystallographic preferred orientation of (100) symmetrical to the tectonic fabric. Type 3 show variable degrees of porphyroclast associated with aggregate, where porphyroclasts display complex compositional zoning that corresponds to lattice distortion, low-angle boundaries, and subgrains, and aggregate CPO mimics porphyroclast orientation. All aggregates accommodated a significant proportion of greenschist facies deformation through grain boundary sliding, grain rotation and impingement, and pressure solution, which lead to a cohesive behavior and overall strain hardening of the aggregates. The characteristic CPO could not have been developed in this manner, and was the result of an older phase of partitioned amphibolite facies dislocation creep, recovery including chemical segregation, and recrystallization of porphyroclasts. This study demonstrates the significance of strain accommodation within garnet and its affect on composition under a range of PT conditions, and emphasizes the importance of utilizing EBSD methods with studies that rely upon a sound understanding of garnet. ?? 2010 Elsevier Ltd.

The soda-ash roasting of chromite ore processing residue for the reclamation of chromium

NASA Astrophysics Data System (ADS)

Antony, M. P.; Tathavadkar, V. D.; Calvert, C. C.; Jha, A.

2001-12-01

Sodium chromate is produced via the soda-ash roasting of chromite ore with sodium carbonate. After the reaction, nearly 15 pct of the chromium oxide remains unreacted and ends up in the waste stream, for landfills. In recent years, the concern over environmental pollution from hexavalent chromium (Cr6+) from the waste residue has become a major problem for the chromium chemical industry. The main purpose of this investigation is to recover chromium oxide present in the waste residue as sodium chromate. Cr2O3 in the residue is distributed between the two spinel solid solutions, Mg(Al,Cr)2O4 and γ-Fe2O3. The residue from the sodium chromate production process was analyzed both physically and chemically. The compositions of the mineral phases were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The influence of alkali addition on the overall reaction rate is examined. The kinetics of the chromium extraction reaction resulting from the residue of the soda-ash roasting process under an oxidizing atmosphere is also investigated. It is shown that the experimental results for the roasting reaction can be best described by the Ginstling and Brounshtein (GB) equation for diffusion-controlled kinetics. The apparent activation energy for the roasting reaction was calculated to be between 85 and 90 kJ·mol-1 in the temperature range 1223 to 1473 K. The kinetics of leaching of Cr3+ ions using the aqueous phase from the process residue is also studied by treating the waste into acid solutions with different concentrations.

Benefits of Ilizarov automated bone distraction for nerves and articular cartilage in experimental leg lengthening.

PubMed

Shchudlo, Nathalia; Varsegova, Tatyana; Stupina, Tatyana; Shchudlo, Michael; Saifutdinov, Marat; Yemanov, Andrey

2017-09-18

To determine peculiarities of tissue responses to manual and automated Ilizarov bone distraction in nerves and articular cartilage. Twenty-nine dogs were divided in two experimental groups: Group M - leg lengthening with manual distraction (1 mm/d in 4 steps), Group A - automated distraction (1 mm/d in 60 steps) and intact group. Animals were euthanized at the end of distraction, at 30 th day of fixation in apparatus and 30 d after the fixator removal. M-responses in gastrocnemius and tibialis anterior muscles were recorded, numerical histology of peroneal and tibialis nerves and knee cartilage semi-thin sections, scanning electron microscopy and X-ray electron probe microanalysis were performed. Better restoration of M-response amplitudes in leg muscles was noted in A-group. Fibrosis of epineurium with adipocytes loss in peroneal nerve, subperineurial edema and fibrosis of endoneurium in some fascicles of both nerves were noted only in M-group, shares of nerve fibers with atrophic and degenerative changes were bigger in M-group than in A-group. At the end of experiment morphometric parameters of nerve fibers in peroneal nerve were comparable with intact nerve only in A-group. Quantitative parameters of articular cartilage (thickness, volumetric densities of chondrocytes, percentages of isogenic clusters and empty cellular lacunas, contents of sulfur and calcium) were badly changed in M-group and less changed in A-group. Automated Ilizarov distraction is more safe method of orthopedic leg lengthening than manual distraction in points of nervous fibers survival and articular cartilage arthrotic changes.

Benefits of Ilizarov automated bone distraction for nerves and articular cartilage in experimental leg lengthening

PubMed Central

Shchudlo, Nathalia; Varsegova, Tatyana; Stupina, Tatyana; Shchudlo, Michael; Saifutdinov, Marat; Yemanov, Andrey

2017-01-01

AIM To determine peculiarities of tissue responses to manual and automated Ilizarov bone distraction in nerves and articular cartilage. METHODS Twenty-nine dogs were divided in two experimental groups: Group M - leg lengthening with manual distraction (1 mm/d in 4 steps), Group A - automated distraction (1 mm/d in 60 steps) and intact group. Animals were euthanized at the end of distraction, at 30th day of fixation in apparatus and 30 d after the fixator removal. M-responses in gastrocnemius and tibialis anterior muscles were recorded, numerical histology of peroneal and tibialis nerves and knee cartilage semi-thin sections, scanning electron microscopy and X-ray electron probe microanalysis were performed. RESULTS Better restoration of M-response amplitudes in leg muscles was noted in A-group. Fibrosis of epineurium with adipocytes loss in peroneal nerve, subperineurial edema and fibrosis of endoneurium in some fascicles of both nerves were noted only in M-group, shares of nerve fibers with atrophic and degenerative changes were bigger in M-group than in A-group. At the end of experiment morphometric parameters of nerve fibers in peroneal nerve were comparable with intact nerve only in A-group. Quantitative parameters of articular cartilage (thickness, volumetric densities of chondrocytes, percentages of isogenic clusters and empty cellular lacunas, contents of sulfur and calcium) were badly changed in M-group and less changed in A-group. CONCLUSION Automated Ilizarov distraction is more safe method of orthopedic leg lengthening than manual distraction in points of nervous fibers survival and articular cartilage arthrotic changes. PMID:28979852

Ferrite Formation Dynamics and Microstructure Due to Inclusion Engineering in Low-Alloy Steels by Ti2O3 and TiN Addition

NASA Astrophysics Data System (ADS)

Mu, Wangzhong; Shibata, Hiroyuki; Hedström, Peter; Jönsson, Pär Göran; Nakajima, Keiji

2016-08-01

The dynamics of intragranular ferrite (IGF) formation in inclusion engineered steels with either Ti2O3 or TiN addition were investigated using in situ high temperature confocal laser scanning microscopy. Furthermore, the chemical composition of the inclusions and the final microstructure after continuous cooling transformation was investigated using electron probe microanalysis and electron backscatter diffraction, respectively. It was found that there is a significant effect of the chemical composition of the inclusions, the cooling rate, and the prior austenite grain size on the phase fractions and the starting temperatures of IGF and grain boundary ferrite (GBF). The fraction of IGF is larger in the steel with Ti2O3 addition compared to the steel with TiN addition after the same thermal cycle has been imposed. The reason for this difference is the higher potency of the TiO x phase as nucleation sites for IGF formation compared to the TiN phase, which was supported by calculations using classical nucleation theory. The IGF fraction increases with increasing prior austenite grain size, while the fraction of IGF in both steels was the highest for the intermediate cooling rate of 70 °C/min, since competing phase transformations were avoided, the structure of the IGF was though refined with increasing cooling rate. Finally, regarding the starting temperatures of IGF and GBF, they decrease with increasing cooling rate and the starting temperature of GBF decreases with increasing grain size, while the starting temperature of IGF remains constant irrespective of grain size.

The Effect of the Acetone Extract of Arctotis arctotoides (Asteraceae) on the Growth and Ultrastructure of Some Opportunistic Fungi Associated with HIV/AIDS

PubMed Central

Otang, Wilfred M.; Grierson, Donald S.; Ndip, Roland N.

2011-01-01

In this study, the effect of the acetone extract of Arctotis arctotoides (L.f.) O. Hoffm. (Asteraceae) on the growth and ultrastructure of some opportunistic fungi associated with HIV/AIDS was analyzed by means of scanning electron microscope (SEM). Remarkable morphological alterations in the fungal mycelia which were attributed to the loss of cell wall strength ranged from loss of turgidity and uniformity, collapse of entire hyphae to evident destruction of the hyphae. The elements responsible for giving the fungi their characteristic virulence were detected and quantified by energy dispersive X-ray microanalysis techniques. X-ray microanalysis showed the specific spectra of sodium, potassium and sulfur as the principal intersection of the four pathogenic fungi studied. Since these ions have the potential of fostering fungal invasion by altering the permeability of hosts’ membranes, their presence was considered inherent to the pathogenicity of the opportunistic fungi. Hence, these findings indicate the potential of the crude extract of A. arctotoides in preventing fungal invasion and subsequent infection of host’s membranes. PMID:22272130

Intermetallic Precipitation in Low-Density Steel

NASA Astrophysics Data System (ADS)

Chatterjee, S.; Chatterjee, A.; Chakrabarti, D.

2018-06-01

Low-density steels (LDS) represent a relatively new class of material that contains a large concentration of aluminum. In the present work, we studied the effect of copper addition to these steels. Microanalysis and electron diffraction study were used to demonstrate that on the contrary to the theoretical expectation, copper formed a variety of intermetallic, instead of metallic, precipitates on reaction with aluminum. The precipitation led to a significant age-hardening response that imparted a special characteristic to this material, which had never been reported previously.

"Cold" synthesis of carbon from polyvinyl chloride with the use of an electron beam ejected into the atmosphere

NASA Astrophysics Data System (ADS)

Kryazhev, Yu. G.; Vorob'ev, M. S.; Koval', N. N.; Trenikhin, M. V.; Solodovnichenko, V. S.; Sulakshin, S. A.; Likholobov, V. A.

2016-10-01

This work shows the possibility in principle of forming hydrocarbon structures in polyvinyl chloride films free of admixtures and polyvinyl chloride films modified with 5-mass % ferrocene via a radiation chemical transformation in the atmosphere with the use of an electron accelerator with a plasma cathode operating in the pulsed-periodic mode maximal electron energy no higher than 160 keV, pulse length of 40 μs, and current density of 5 mA/cm2. According to the results of semiquantitative X-ray microanalysis, an irradiated polyvinyl chloride film free of admixtures contains 92 of carbon, 6 of oxygen, and 2 mass % of chlorine; the irradiated polyvinyl chloride is an amorphous carbon material. A possible mechanism of the phenomenon is discussed.

Determination of elemental distribution in green micro-algae using synchrotron radiation nano X-ray fluorescence (SR-nXRF) and electron microscopy techniques--subcellular localization and quantitative imaging of silver and cobalt uptake by Coccomyxa actinabiotis.

PubMed

Leonardo, T; Farhi, E; Boisson, A-M; Vial, J; Cloetens, P; Bohic, S; Rivasseau, C

2014-02-01

The newly discovered unicellular micro-alga Coccomyxa actinabiotis proves to be highly radio-tolerant and strongly concentrates radionuclides, as well as large amounts of toxic metals. This study helps in the understanding of the mechanisms involved in the accumulation and detoxification of silver and cobalt. Elemental distribution inside Coccomyxa actinabiotis cells was determined using synchrotron nano X-ray fluorescence spectroscopy at the ID22 nano fluorescence imaging beamline of the European Synchrotron Radiation Facility. The high resolution and high sensitivity of this technique enabled the assessment of elemental associations and exclusions in subcellular micro-algae compartments. A quantitative treatment of the scans was implemented to yield absolute concentrations of each endogenous and exogenous element with a spatial resolution of 100 nm and compared to the macroscopic content in cobalt and silver determined using inductively coupled plasma-mass spectrometry. The nano X-ray fluorescence imaging was complemented by transmission electron microscopy coupled to X-ray microanalysis (TEM-EDS), yielding differential silver distribution in the cell wall, cytosol, nucleus, chloroplast and mitochondria with unique resolution. The analysis of endogenous elements in control cells revealed that iron had a unique distribution; zinc, potassium, manganese, molybdenum, and phosphate had their maxima co-localized in the same area; and sulfur, copper and chlorine were almost homogeneously distributed among the whole cell. The subcellular distribution and quantification of cobalt and silver in micro-alga, assessed after controlled exposure to various concentrations, revealed that exogenous metals were mainly sequestered inside the cell rather than on mucilage or the cell wall, with preferential compartmentalization. Cobalt was homogeneously distributed outside of the chloroplast. Silver was localized in the cytosol at low concentration and in the whole cell excluding the nucleus at high concentration. Exposure to low concentrations of cobalt or silver did not alter the localization nor the concentration of endogenous elements within the cells. To our knowledge, this is the first report on element co-localization and segregation at the sub-cellular level in micro-algae by means of synchrotron nano X-ray fluorescence spectroscopy.

Comparative Analysis of Microbial Communities in Iron-Dominated Flocculent Mats in Deep-Sea Hydrothermal Environments.

PubMed

Makita, Hiroko; Kikuchi, Sakiko; Mitsunobu, Satoshi; Takaki, Yoshihiro; Yamanaka, Toshiro; Toki, Tomohiro; Noguchi, Takuroh; Nakamura, Kentaro; Abe, Mariko; Hirai, Miho; Yamamoto, Masahiro; Uematsu, Katsuyuki; Miyazaki, Junichi; Nunoura, Takuro; Takahashi, Yoshio; Takai, Ken

2016-10-01

It has been suggested that iron is one of the most important energy sources for photosynthesis-independent microbial ecosystems in the ocean crust. Iron-metabolizing chemolithoautotrophs play a key role as primary producers, but little is known about their distribution and diversity and their ecological role as submarine iron-metabolizing chemolithotrophs, particularly the iron oxidizers. In this study, we investigated the microbial communities in several iron-dominated flocculent mats found in deep-sea hydrothermal fields in the Mariana Volcanic Arc and Trough and the Okinawa Trough by culture-independent molecular techniques and X-ray mineralogical analyses. The abundance and composition of the 16S rRNA gene phylotypes demonstrated the ubiquity of zetaproteobacterial phylotypes in iron-dominated mat communities affected by hydrothermal fluid input. Electron microscopy with energy-dispersive X-ray microanalysis and X-ray absorption fine structure (XAFS) analysis revealed the chemical and mineralogical signatures of biogenic Fe-(oxy)hydroxide species and the potential contribution of Zetaproteobacteria to the in situ generation. These results suggest that putative iron-oxidizing chemolithoautotrophs play a significant ecological role in producing iron-dominated flocculent mats and that they are important for iron and carbon cycles in deep-sea low-temperature hydrothermal environments. We report novel aspects of microbiology from iron-dominated flocculent mats in various deep-sea environments. In this study, we examined the relationship between Zetaproteobacteria and iron oxides across several hydrothermally influenced sites in the deep sea. We analyzed iron-dominated mats using culture-independent molecular techniques and X-ray mineralogical analyses. The scanning electron microscopy-energy-dispersive X-ray spectroscopy SEM-EDS analysis and X-ray absorption fine structure (XAFS) analysis revealed chemical and mineralogical signatures of biogenic Fe-(oxy)hydroxide species as well as the potential contribution of the zetaproteobacterial population to the in situ production. These key findings provide important information for understanding the mechanisms of both geomicrobiological iron cycling and the formation of iron-dominated mats in deep-sea hydrothermal fields. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

How Does Microanalysis of Mother-Infant Communication Inform Maternal Sensitivity and Infant Attachment?

PubMed Central

Beebe, Beatrice; Steele, Miriam

2013-01-01

Microanalysis research on 4-month mother-infant face-to-face communication operates like a “social microscope” and identifies aspects of maternal sensitivity and the origins of attachment with a more detailed lens. We hope to enhance a dialogue between these two paradigms, microanalysis of mother-infant communication and maternal sensitivity and emerging working models of attachment. The prediction of infant attachment from microanalytic approaches and their contribution to concepts of maternal sensitivity are described. We summarize aspects of one microanalytic study by Beebe and colleagues (2010) that documents new communication patterns between mothers and infants at 4 months that predict future disorganized (vs. secure) attachment. The microanalysis approach opens up a new window on the details of the micro-processes of face-to-face communication. It provides a new, rich set of behaviors with which to extend our understanding of the origins of infant attachment and of maternal sensitivity. PMID:24299136

How does microanalysis of mother-infant communication inform maternal sensitivity and infant attachment?

PubMed

Beebe, Beatrice; Steele, Miriam

2013-01-01

Microanalysis research on 4-month infant-mother face-to-face communication operates like a "social microscope" and identifies aspects of maternal sensitivity and the origins of attachment with a more detailed lens. We hope to enhance a dialogue between these two paradigms, microanalysis of mother-infant communication and maternal sensitivity and emerging working models of attachment. The prediction of infant attachment from microanalytic approaches and their contribution to concepts of maternal sensitivity are described. We summarize aspects of one microanalytic study by Beebe and colleagues published in 2010 that documents new communication patterns between mothers and infants at 4 months that predict future disorganized (vs. secure) attachment. The microanalysis approach opens up a new window on the details of the micro-processes of face-to-face communication. It provides a new, rich set of behaviors with which to extend our understanding of the origins of infant attachment and of maternal sensitivity.

Chemical speciation of individual airborne particles by the combined use of quantitative energy-dispersive electron probe X-ray microanalysis and attenuated total reflection Fourier transform-infrared imaging techniques.

PubMed

Song, Young-Chul; Ryu, JiYeon; Malek, Md Abdul; Jung, Hae-Jin; Ro, Chul-Un

2010-10-01

In our previous work, it was demonstrated that the combined use of attenuated total reflectance (ATR) FT-IR imaging and quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), named low-Z particle EPMA, had the potential for characterization of individual aerosol particles. Additionally, the speciation of individual mineral particles was performed on a single particle level by the combined use of the two techniques, demonstrating that simultaneous use of the two single particle analytical techniques is powerful for the detailed characterization of externally heterogeneous mineral particle samples and has great potential for characterization of atmospheric mineral dust aerosols. These single particle analytical techniques provide complementary information on the physicochemical characteristics of the same individual particles, such as low-Z particle EPMA on morphology and elemental concentrations and the ATR-FT-IR imaging on molecular species, crystal structures, functional groups, and physical states. In this work, this analytical methodology was applied to characterize an atmospheric aerosol sample collected in Incheon, Korea. Overall, 118 individual particles were observed to be primarily NaNO(3)-containing, Ca- and/or Mg-containing, silicate, and carbonaceous particles, although internal mixing states of the individual particles proved complicated. This work demonstrates that more detailed physiochemical properties of individual airborne particles can be obtained using this approach than when either the low-Z particle EPMA or ATR-FT-IR imaging technique is used alone.

Dopant-Site Determination in Y- and Sc-Doped (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ by Atom Location by Channeling Enhanced Microanalysis and the Role of Dopant Site on Secondary Phase Formation.

PubMed

Meffert, Matthias; Störmer, Heike; Gerthsen, Dagmar

2016-02-01

(Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ (BSCF) is a promising material with mixed ionic and electronic conductivity which is considered for oxygen separation membranes. Selective improvement of material properties, e.g. oxygen diffusivity or suppression of secondary phase formation, can be achieved by B-site doping. This study is concerned with the formation of Co-oxide precipitates in undoped BSCF at typical homogenization temperatures of 1,000°C, which act as undesirable nucleation sites for other secondary phases in the application-relevant temperature range. Y-doping successfully suppresses Co-oxide formation, whereas only minor improvements are achieved by Sc-doping. To understand the reason for the different behavior of Y and Sc, the lattice sites of dopant cations in BSCF were experimentally determined in this work. Energy-dispersive X-ray spectroscopy in a transmission electron microscope was applied to locate dopant sites exploiting the atom location by channeling enhanced microanalysis technique. It is shown that Sc exclusively occupies B-cation sites, whereas Y is detected on A- and B-cation sites in Y-doped BSCF, although solely B-site doping was intended. A model is presented for the suppression of Co-oxide formation in Y-doped BSCF based on Y double-site occupancy.

Normal incidence X-ray mirror for chemical microanalysis

DOEpatents

Carr, Martin J.; Romig, Jr., Alton D.

1990-01-01

A non-planar, focusing mirror, to be utilized in both electron column instruments and micro-x-ray fluorescence instruments for performing chemical microanalysis on a sample, comprises a concave, generally spherical base substrate and a predetermined number of alternating layers of high atomic number material and low atomic number material contiguously formed on the base substrate. The thickness of each layer is an integral multiple of the wavelength being reflected and may vary non-uniformly according to a predetermined design. The chemical analytical instruments in which the mirror is used also include a predetermined energy source for directing energy onto the sample and a detector for receiving and detecting the x-rays emitted from the sample; the non-planar mirror is located between the sample and detector and collects the x-rays emitted from the sample at a large solid angle and focuses the collected x-rays to the sample. For electron column instruments, the wavelengths of interest lie above 1.5 nm, while for x-ray fluorescence instruments, the range of interest is below 0.2 nm. Also, x-ray fluorescence instruments include an additional non-planar focusing mirror, formed in the same manner as the previously described m The invention described herein was made in the performance of work under contract with the Department of Energy, Contract No. DE-AC04-76DP00789, and the United States Government has rights in the invention pursuant to this contract.

Iron speciation of airborne subway particles by the combined use of energy dispersive electron probe X-ray microanalysis and Raman microspectrometry.

PubMed

Eom, Hyo-Jin; Jung, Hae-Jin; Sobanska, Sophie; Chung, Sang-Gwi; Son, Youn-Suk; Kim, Jo-Chun; Sunwoo, Young; Ro, Chul-Un

2013-11-05

Quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), known as low-Z particle EPMA, and Raman microspectrometry (RMS) were applied in combination for an analysis of the iron species in airborne PM10 particles collected in underground subway tunnels. Iron species have been reported to be a major chemical species in underground subway particles generated mainly from mechanical wear and friction processes. In particular, iron-containing particles in subway tunnels are expected to be generated with minimal outdoor influence on the particle composition. Because iron-containing particles have different toxicity and magnetic properties depending on their oxidation states, it is important to determine the iron species of underground subway particles in the context of both indoor public health and control measures. A recently developed analytical methodology, i.e., the combined use of low-Z particle EPMA and RMS, was used to identify the chemical species of the same individual subway particles on a single particle basis, and the bulk iron compositions of airborne subway particles were also analyzed by X-ray diffraction. The majority of airborne subway particles collected in the underground tunnels were found to be magnetite, hematite, and iron metal. All the particles collected in the tunnels of underground subway stations were attracted to permanent magnets due mainly to the almost ubiquitous ferrimagnetic magnetite, indicating that airborne subway particles can be removed using magnets as a control measure.

New developments in electron microscopy for serial image acquisition of neuronal profiles.

PubMed

Kubota, Yoshiyuki

2015-02-01

Recent developments in electron microscopy largely automate the continuous acquisition of serial electron micrographs (EMGs), previously achieved by laborious manual serial ultrathin sectioning using an ultramicrotome and ultrastructural image capture process with transmission electron microscopy. The new systems cut thin sections and capture serial EMGs automatically, allowing for acquisition of large data sets in a reasonably short time. The new methods are focused ion beam/scanning electron microscopy, ultramicrotome/serial block-face scanning electron microscopy, automated tape-collection ultramicrotome/scanning electron microscopy and transmission electron microscope camera array. In this review, their positive and negative aspects are discussed. © The Author 2015. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Bioinorganic chemical composition of the lens and methods of its investigation].

PubMed

Avetisov, S E; Novikov, I A; Pakhomova, N A; Motalov, V G

2018-01-01

Bioinorganic chemical composition of the lens of human and experimental animals (cows, dogs, rats, rabbits) have been analyzed in various studies. In most cases, the studies employed different methods to determine the gross (total) composition of chemical elements and their concentrations in the examined samples. Less frequently, they included an assessment of the distribution of chemical elements in the lens and correlation of their concentration with its morphological changes. Chemical elements from all groups (series) of the periodic classification system were discovered in the lens substance. Despite similar investigation methods, different authors obtained contradicting results on the chemical composition of the lens. This article presents data suggesting possible correlation between inorganic chemical elements in the lens substance with the development and formation of lenticular opacities. All currently employed methods are known to only analyze limited number of select chemical elements in the tissues and do not consider the whole range of elements that can be analyzed with existing technology; furthermore, the majority of studies are conducted on the animal model lens. Therefore, it is feasible to continue the development of the chemical microanalysis method by increasing the sensitivity of Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) with the purpose of assessing the gross chemical composition and distribution of the elements in the lens substance, as well as revealing possible correlation between element concentration and morphological changes in the lens.

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

NASA Astrophysics Data System (ADS)

Silva, Cleiton Carvalho; de Albuquerque, Victor Hugo C.; Miná, Emerson Mendonça; Moura, Elineudo P.; Tavares, João Manuel R. S.

2018-03-01

The aim of this work was to evaluate the different phases formed during solidification and after thermal aging of the as-welded 625 nickel-based alloy, as well as the influence of microstructural changes on the mechanical properties. The experiments addressed aging temperatures of 650 and 950 °C for 10, 100, and 200 hours. The samples were analyzed by electron microscopy, microanalysis, and X-ray diffraction in order to identify the secondary phases. Mechanical tests such as hardness, microhardness, and Charpy-V impact test were performed. Nondestructive ultrasonic inspection was also conducted to correlate the acquired signals with mechanical and microstructural properties. The results show that the alloy under study experienced microstructural changes when aged at 650 °C. The aging was responsible by the dissolution of the Laves phase formed during the solidification and the appearance of γ″ phase within interdendritic region and fine carbides along the solidification grain boundaries. However, when it was aged at 950 °C, the Laves phase was continuously dissolved and the excess Nb caused the precipitation of the δ-phase (Ni3Nb), which was intensified at 10 hours of aging, with subsequent dissolution for longer periods such as 200 hours. Even when subjected to significant microstructural changes, the mechanical properties, especially toughness, were not sensitive to the dissolution and/or precipitation of the secondary phases.

Some aspects of water quality in a polluted lowland river in relation to the intracellular chemical levels in planktonic and epilithic diatoms.

PubMed

Tien, Chien-Jung

2004-04-01

Changes in elemental concentrations of diatoms and river water from the river Erh-Jen were determined using scanning electron microscopy energy-dispersive X-ray microanalysis and inductively coupled plasma mass spectrometry. Relatively large amounts of copper and lead found in both planktonic and epilithic diatoms implied these algae might play an important role in biogeochemical cycles and in the transfer of those elements to higher trophic levels in the aquatic environment. Changes in elemental concentrations within diatom cells were found to vary with other elements within cells and the same or different elements in water. Planktonic and epilithic cells showed different correlation patterns. For epilithic diatoms, negative correlations were found between concentrations of total phosphorus and phosphate in water and those of phosphorus within cells, and between concentrations of lead in water and in cells. Concentrations of chromium and mercury within planktonic cells and those of phosphorus, manganese and lead within epilithic ones were found to be easily influenced by other elements in river water, indicating appearance of the competitive manner on uptake of such elements by algal cells. Relatively high concentration factors (CFs) for cadmium, mercury and lead by diatoms in this study suggested they are good accumulators for these heavy metals. Significant negative corrections were found between the CFs of diatoms and the concentrations of elements in river water.

Unique zinc mass in mandibles separates drywood termites from other groups of termites

NASA Astrophysics Data System (ADS)

Cribb, Bronwen W.; Stewart, Aaron; Huang, Han; Truss, Rowan; Noller, Barry; Rasch, Ronald; Zalucki, Myron P.

2008-05-01

Previously, the presence of metals in arthropod mandibles has been linked with harder cuticle, and in termites, a 20% increase in hardness has been found for mandibles containing major quantities of zinc. The current study utilises electron microscopy and energy-dispersive X-ray microanalysis to assess incidence and abundance of metals in all extant subfamilies of the Isoptera. The basal clades contain no zinc and little to no manganese in the cutting edge of the mandible cuticle, suggesting that these states are ancestral for termites. However, experimentation with mandibles in vitro indicates the presence of some elements of the cuticular biochemistry necessary to enable uptake of zinc. The Termopsidae, Serritermitidae, Rhinotermitidae and Termitidae all contain minor quantities of manganese, while trace to minor quantities of zinc occur in all except the Serritermitidae. In contrast, all Kalotermitidae or drywood termites contain major levels of zinc in the mandible edge. Diet and life type are explored as links to metal profiles across the termites. The presence of harder mandibles in the drywood termites may be related to lack of access to free water with which to moisten wood. Scratch tests were applied to a set of mandibles. The coefficient of friction for Cryptotermes primus (Kalotermitidae) mandibles, when compared with species from other subfamilies, indicates that zinc-containing mandibles are likely to be more scratch resistant.

Mineralogical gradients associated with alvinellids at deep-sea hydrothermal vents

NASA Astrophysics Data System (ADS)

Zbinden, Magali; Le Bris, Nadine; Compère, Philippe; Martinez, Isabelle; Guyot, François; Gaill, Françoise

2003-02-01

Alvinella pompejana and Alvinella caudata live in organic tubes on active sulphide chimney walls at deep-sea hydrothermal vents. These polychaete annelids are exposed to extreme thermal and chemical gradients and to intense mineral precipitation. This work points out that mineral particles associated with Pompeii worm ( A. pompejana and A. caudata) tubes constitute useful markers for evaluating the chemical characteristics of their micro-environment. The minerals associated with these worm tubes were analysed on samples recovered from an experimental alvinellid colony, at different locations in the vent fluid-seawater interface. Inhabited tubes from the most upper and lower parts of the colony were analysed by light and electron microscopies, X-ray microanalysis and X-ray diffraction. A change was observed from a Fe-Zn-S mineral assemblage to a Zn-S assemblage at the millimeter scale from the outer to the inner face of a tube. A similar gradient in proportions of minerals was observed at a decimeter scale from the lower to the upper part of the colony. The marcasite/pyrite ratio of iron disulphides also displays a steep decrease along the few millimeters adjacent to the external tube surface. The occurrence of these gradients indicates that the micro-environment within the tube differs from that outside the tube, and suggests that the tube wall acts as an efficient barrier to the external environment.

Trace metal fractionation as a mean to improve on the management of contaminated sediments from runoff water in infiltration basins.

PubMed

Al Husseini, Amelène El-Mufleh; Béchet, Béatrice; Gaudin, Anne; Ruban, Véronique

2013-01-01

The management of stormwater sediment is a key issue for local authorities due to the pollution load and significant tonnages. In view of reuse, for example for civil engineering, the environmental evaluation of these highly aggregated sediments requires the study of the fractionation and mobility of trace metals. The distribution of trace metals (Cd, Cr, Cu, Ni, Pb, Zn) and their level of lability in three French stormwater sediments was determined using sequential and kinetic extractions (EDTA reagent) associated with mineralogical analysis and scanning electron microscopy observations. Using microanalysis, new data were acquired on the evolution of aggregate state during extractions, and on its significant role in the retention of trace metals. Trace metals were, in particular, observed to be very stable in small aggregates (10-50 microm). Comparison of the two extraction methods revealed that EDTA extraction was not convenient for evaluating the stable fraction of Cr, Ni and Zn. Moreover, the results were relevant for basins presenting similar sources of trace metals, whatever the physicochemical conditions in basins. The results suggest that the management of stormwater sediments could be improved by a better knowledge of metal mobility, as chemical extractions could highlight the localization of the mobile fraction of trace metals. Treatment could be therefore avoided, or specific treatment could be applied to a reduced volume of sediments.

Modeling the surface contamination of dental titanium investment castings.

PubMed

Atwood, R C; Lee, P D; Curtis, R V

2005-02-01

The objective of this study was to develop a computational tool for assisting the design of titanium dental castings with minimal defects and to compare computational simulations with casting experiments. Modeling. An in-house cellular-automata solidification and finite-difference diffusion program was coupled with a commercial casting program and applied to (a) simple geometric wedge models and (b) a 3D-laser scan of a molar crown casting. Experimental. Wedges and molar crowns were hand-waxed and investment cast in commercial purity grade 1 (CP-1) titanium by a commercial dental laboratory. The castings were sectioned and analyzed using light and scanning electron microscopy, X-ray microanalysis, and microhardness testing. In the wedge sample, contamination with impurities (Al, Si), including intermetallic precipitates, was found to extend to a depth ranging from 30 to 120 microm depending on the section thickness and hence the local cooling rate. Microstructural and mechanical (hardness) effects were found to a depth ranging from 80 to 250 microm. The coupled micro/macro model predictions showed reasonable agreement for the pattern of contamination. Dental and medical applications demand close dimensional tolerance and freedom from surface impurities and structural flaws in castings having unique shapes. The ability to predict the structural, mechanical, and chemical changes resulting from the casting process will help to design the casting and post-casting processes to minimize these problems.

X-ray microanalytical studies of mineral elements in the tripartite symbiosis between lima bean, N2-fixing bacteria and mycorrhizal fungi.

PubMed

Rodak, Bruna Wurr; Freitas, Douglas Siqueira; Bamberg, Soraya Marx; Carneiro, Marco Aurélio Carbone; Guilherme, Luiz Roberto Guimarães

2017-01-01

The symbiosis between legumes, arbuscular mycorrhizal (AM) fungi, and N 2 -fixing bacteria (NFB) provides mutual nutritional gains. However, assessing the nutritional status of the microorganisms is a difficult task. A methodology that could assess this status, in situ, could assist managing these organisms in agriculture. This study used X-ray microanalyses to quantify and locate mineral elements in structures formed in a tripartite symbiosis. Lima bean (Phaseolus lunatus L. Walp) was cultivated in pots under greenhouse conditions, to which we have added AM fungal isolates (Glomus macrocarpum and Acaulospora colombiana) and NFB (Bradyrhizobium japonicum) inocula. Uninoculated control plants were also included. Symbionts were evaluated at the onset of flowering. Quantification of the mineral elements in the symbiotic components was performed using energy dispersive X-ray spectroscopy (EDX) and a scanning electron microscopy (SEM) was used to identify structures. EDX analysis detected 13 elements with the most abundant being N, Ca, and Se, occurring in all tissues, Fe in roots, Ni and Al in epidermis and P and Mo in nodules. Elemental quantification in fungal structures was not possible. The distribution of elements was related to their symbiotic function. X-ray microanalysis can be efficiently applied for nutritional diagnosis in tripartite symbiosis. Copyright © 2016 Elsevier B.V. All rights reserved.

The mode of action of dimeticone 4% lotion against head lice, Pediculus capitis

PubMed Central

Burgess, Ian F

2009-01-01

Background Treatment of head lice using physically acting preparations based on silicones is currently replacing insecticide use due to widespread resistance to neurotoxic agents. It has been postulated that some products act by asphyxiation, although the limited experimental evidence and the anatomy of the louse respiratory system suggest this is unlikely. Results Observation over several hours of lice treated using 4% high molecular weight dimeticone in a volatile silicone base showed that, although rapidly immobilised initially, the insects still exhibited small movements of extremities and death was delayed. One common effect of treatment is inhibition of the louse's ability to excrete water by transpiration through the spiracles. Inability to excrete water that is ingested as part of the louse blood meal appears to subject the louse gut to osmotic stress resulting in rupture. Scanning electron microscopy coupled with X-ray microanalysis to detect silicon showed dimeticone lotion is deposited in the spiracles and distal region of the tracheae of lice and in some cases blocks the lumen or opening entirely. Conclusion This work raises doubts that lice treated using dimeticone preparations die from anoxia despite blockage of the outer respiratory tract because movements can be observed for hours after exposure. However, the blockage inhibits water excretion, which causes physiological stress that leads to death either through prolonged immobilisation or, in some cases, disruption of internal organs such as the gut. PMID:19232080

Corrosion-Resistant Ti- xNb- xZr Alloys for Nitric Acid Applications in Spent Nuclear Fuel Reprocessing Plants

NASA Astrophysics Data System (ADS)

Manivasagam, Geetha; Anbarasan, V.; Kamachi Mudali, U.; Raj, Baldev

2011-09-01

This article reports the development, microstructure, and corrosion behavior of two new alloys such as Ti-4Nb-4Zr and Ti-2Nb-2Zr in boiling nitric acid environment. The corrosion test was carried out in the liquid, vapor, and condensate phases of 11.5 M nitric acid, and the potentiodynamic anodic polarization studies were performed at room temperature for both alloys. The samples subjected to three-phase corrosion testing were characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX). As Ti-2Nb-2Zr alloy exhibited inferior corrosion behavior in comparison to Ti-4Nb-4Zr in all three phases, weldability and heat treatment studies were carried out only on Ti-4Nb-4Zr alloy. The weldability of the new alloy was evaluated using tungsten inert gas (TIG) welding processes, and the welded specimen was thereafter tested for its corrosion behavior in all three phases. The results of the present investigation revealed that the newly developed near alpha Ti-4Nb-4Zr alloy possessed superior corrosion resistance in all three phases and excellent weldability compared to conventional alloys used for nitric acid application in spent nuclear reprocessing plants. Further, the corrosion resistance of the beta heat-treated Ti-4Nb-4Zr alloy was superior when compared to the sample heat treated in the alpha + beta phase.

Testing a laser-induced breakdown spectroscopy technique on the Arctic sediments

NASA Astrophysics Data System (ADS)

Han, D.; Nam, S. I.

2017-12-01

Physical and geochemical investigations coupled with the Laser-induced Breakdown Spectroscopy (LIBS) were performed on three surface sediment cores (ARA03B/24BOX, ARA02B/01(A)MUC, ARA02B/02MUC and ARA02B/03(A)MUC) recovered from the western Arctic Ocean (Chukchi Sea) during IBRV ARON expeditions in 2012. The LIBS technique was applied to carry out elemental chemical analysis of the Arctic sediments and compared with that measured by ITRAX X-ray fuorescence (XRF) core scanning. LIBS and XRF have shown similar elemental composition within each sediment core. In this study, mineral composition (XRD), grain size distribution and organic carbon content as well as elemental composition (LIBS) were all considered to understand paleoenvironmental changes (ocean circulation, sea-ice drift, iceberg discharge, and etc.) recorded in the Arctic Holocene sediment. Quantitative LIBS analysis shows a gradually varying distribution of the elements along the sampled core and clear separation between the cores. The cores are geochemically characterized by elevated Mn profile. The gradient of mineral composition and grain sizes among the cores shows regional distribution and variation in sedimentary condition due to geological distance between East Siberian and North America. The present study reveals that a LIBS technique can be employed for in-situ sediment analyses for the Arctic Ocean. Furthermore, LIBS does not require costly equipment, trained operators, and complicated sample pre-treatment processes compared to Atomic absorption spectroscopy (AAS) and inductively coupled plasma emission spectroscopy (ICP), and also known to show relatively high levels of sensitivity, precision, and distinction than XRF analysis, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), and electron probe X-ray microanalysis (EPMA).

Microstructure, texture evolution and magnetic properties of strip-casting non-oriented 6.5 wt.% Si electrical steel doped with cerium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hao-Ze, E-mail: lhzqq83@163.com; Liu, Hai-Tao; Liu, Zhen-Yu, E-mail: zyliu@mail.neu.edu.cn

A 0.3 mm thick non-oriented 6.5 wt.% Si electrical steel sheet doped with cerium is produced by twin-roll strip casting, hot rolling, warm rolling and annealing. A detailed study of the cerium precipitates in the as-cast strip, microstructure and texture evolution at different processing stages is carried out by electron probe micro-analysis, optical microscopy, X-ray diffraction and electron backscattered diffraction analysis. Grain interior distributing precipitates identified as Ce-oxides, Ce-oxysulfides and Ce-phosphides, and boundary distributing Ce-oxides and Ce-phosphides are observed in the as-cast strip. The initial as-cast strip is characterized by a much finer solidification microstructure and dominated by obvious //ND texture through the strip thickness. After hot and warm rolling, inhomogeneous microstructure containing large amounts of in-grain shear bands is characterized by mixed < 110 >//RD and < 111 >//ND textures. The texture of the annealed sheet with a relatively large average grain size is far more optimized by the domination of the beneficial cube, rotated cube, (001)< 120 > to (001)< 130 > and Goss texture components, and the elimination of the detrimental γ-fiber texture, leading to a superior magnetic induction and improved iron loss. - Highlights: • An Fe–6.5 wt.% Si as-cast strip doped with cerium was produced. • A thin warm rolled sheet with limited edge cracks was obtained. • Microstructure and texture evolution at each stage were investigated. • Strong λ-fiber and Goss recrystallization textures were formed. • The magnetic properties of the annealed sheet were significantly improved.« less

Diffusion Barrier Selection from Refractory Metals (Zr, Mo and Nb) via Interdiffusion Investigation for U-Mo RERTR Fuel Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

K. Huang; C. Kammerer; D. D. Keiser, Jr.

2014-04-01

U-Mo alloys are being developed as low enrichment monolithic fuel under the Reduced Enrichment for Research and Test Reactor (RERTR) Program. Diffusional interactions between the U-Mo fuel alloy and Al-alloy cladding within the monolithic fuel plate construct necessitate incorporation of a barrier layer. Fundamentally, a diffusion barrier candidate must have good thermal conductivity, high melting point, minimal metallurgical interaction, and good irradiation performance. Refractory metals, Zr, Mo, and Nb are considered based on their physical properties, and the diffusion behavior must be carefully examined first with U-Mo fuel alloy. Solid-to-solid U-10wt.%Mo vs. Mo, Zr, or Nb diffusion couples were assembledmore » and annealed at 600, 700, 800, 900 and 1000 degrees C for various times. The interdiffusion microstructures and chemical composition were examined via scanning electron microscopy and electron probe microanalysis, respectively. For all three systems, the growth rate of interdiffusion zone were calculated at 1000, 900 and 800 degrees C under the assumption of parabolic growth, and calculated for lower temperature of 700, 600 and 500 degrees C according to Arrhenius relationship. The growth rate was determined to be about 10 3 times slower for Zr, 10 5 times slower for Mo and 10 6 times slower for Nb, than the growth rates reported for the interaction between the U-Mo fuel alloy and pure Al or Al-Si cladding alloys. Zr, however was selected as the barrier metal due to a concern for thermo- mechanical behavior of UMo/Nb interface observed from diffusion couples, and for ductile-to-brittle transition of Mo near room temperature.« less

Sub-micrometer particles produced by a low-powered AC electric arc in liquids.

PubMed

Jaworski, Jacek A; Fleury, Eric

2012-01-01

The article presents the report of the production of composites of sub-micrometer metal particles in matrix consisted of the metal compounds by means of an AC electric arc in water and paraffin solutions using electrodes carbon-metal and metal-metal (metal: Ni, Fe, Co, Cu). The advantage of this method is the low electric power (from 5 to 10 W) needed in comparison to standard DC arc-discharge methods (0.8 to 3 kW). This method enables the production of particles from conductive material also in wide range of temperature and in solvent which could be either transparent to light or opaque. Moreover the solvent can be electrolyte or insulating liquid. The microstructure of the composite layer was investigated by scanning electron microscopy (SEM), Electron Probe Microanalysis (EPMA) and X-ray. During particles production in water metal oxides were created. Additionally using cobalt-copper, nickel-copper as couple electrodes, insoluble in water copper (II) hydroxide crystal grains were created additionally which crystals shape was depended on transition metal. For iron-copper couple electrodes system the copper (II) hydroxide was not formed. Experiments with sequence production of Ni and Fe particles with C electrode assisting in molten paraffin let to obtain both Ni and Fe particles surrounded by paraffin. After solidification the material was insulator but if locally magnetic field influenced on the liquid solution in that place after solidification a new composite was created which was electric current conductor with resistivity around 0.1 omega x m, was attracted by magnetic field and presented magneto resistance around 0.4% in changing magnetic field in a range 150 mT. After mixing the concentrated paraffin with normal paraffin resistivity of the mixture increased and it became photosensitive and created small voltage under light influence.

Quantitative FE-EPMA measurement of formation and inhibition of carbon contamination on Fe for trace carbon analysis.

PubMed

Tanaka, Yuji; Yamashita, Takako; Nagoshi, Masayasu

2017-04-01

Hydrocarbon contamination introduced during point, line and map analyses in a field emission electron probe microanalysis (FE-EPMA) was investigated to enable reliable quantitative analysis of trace amounts of carbon in steels. The increment of contamination on pure iron in point analysis is proportional to the number of iterations of beam irradiation, but not to the accumulated irradiation time. A combination of a longer dwell time and single measurement with a liquid nitrogen (LN2) trap as an anti-contamination device (ACD) is sufficient for a quantitative point analysis. However, in line and map analyses, contamination increases with irradiation time in addition to the number of iterations, even though the LN2 trap and a plasma cleaner are used as ACDs. Thus, a shorter dwell time and single measurement are preferred for line and map analyses, although it is difficult to eliminate the influence of contamination. While ring-like contamination around the irradiation point grows during electron-beam irradiation, contamination at the irradiation point increases during blanking time after irradiation. This can explain the increment of contamination in iterative point analysis as well as in line and map analyses. Among the ACDs, which are tested in this study, specimen heating at 373 K has a significant contamination inhibition effect. This technique makes it possible to obtain line and map analysis data with minimum influence of contamination. The above-mentioned FE-EPMA data are presented and discussed in terms of the contamination-formation mechanisms and the preferable experimental conditions for the quantification of trace carbon in steels. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Development of Novel Garnet-Type Solid Electrolytes for Potential Application in Lithium Ion Batteries

NASA Astrophysics Data System (ADS)

Narayanan, Sumaletha

The development of promising solid electrolytes having a garnet-like structure has been successfully achieved through solid state (ceramic) method. Various approaches to improve the Li ion conductivity were employed. The first approach involved creating oxide ion vacancies into the crystal structure of parent garnet-like oxide, Li5La3Nb2O 12 to create a novel family of compounds with nominal composition, Li 5La3Nb2-xYxO12-δ (0 ≤ x ≤ 1). The second approach was Li stuffing into the garnet-like oxides to develop a series of Li stuffed novel Li5+2xLa3Nb 2-xYxO12 (0.05 ≤ x ≤ 0.75) and Li6.5 La2.5Ba0.5ZrTaO12. Powder X-ray diffraction (PXRD), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM), electron probe microanalysis (EPMA) coupled with a wavelength-dispersive spectrometer (WDS), 7Li nuclear magnetic resonance (Li-NMR), and AC impedance spectroscopy were employed to characterize the structure, morphology, elemental composition, Li ion sites, and Li ion conductivity. Studies have shown that Li5+2xLa 3Nb2-xYxO12 have turned out to be promising solid electrolytes with high Li ion conductivity (10-4 Scm -1 at ambient temperatures). In addition, all families of garnets are found to be chemically stable with Li cathode materials (Li2MMn 3O8, where M = Fe, Co) up to 400 °C in air. The developed electrolyte materials have the potential to be used in all-solid-state Li ion batteries.

Isomorphous Substitution of Rare-Earth Elements in Lacunary Apatite Pb8Na2(PO4)6.

PubMed

Get'man, Evgeni I; Loboda, Stanislav N; Ignatov, Alexey V; Prisedsky, Vadim V; Abdul Jabar, Mohammed A B; Ardanova, Lyudmyla I

2016-03-07

The substitution of rare-earth elements (REEs) for Pb in the lacunary apatite Pb8Na2(PO4)6 with void structural channels was studied by means of powder X-ray diffraction (including the Rietveld refinement), scanning electron microscopy, energy-dispersive X-ray microanalysis, and IR spectroscopy and also measurements of the electrical conductivity. The substitution limits (xmax in Pb8-xLnxNa2(PO4)6Ox/2) at 800 °C were found to decrease with the atomic number of the REE from 1.40 for La to 0.12 for Yb with a rapid drop from light to heavy lanthanides (between Gd and Tb). The REE atoms substitute for Pb predominantly at Pb2 sites of the apatite structure according to the scheme 2Pb(2+) + □ → 2Ln(3+) + O(2-), where □ is a vacancy in the structural channel. The substitution in lacunary apatite produces quite different changes in the structural parameters compared with broadly studied alkaline-earth hydroxyapatites. In spite of the much lower ionic radii of REE than that of Pb(2+), the mean distances ⟨Pb1-O⟩ somewhat increase, whereas the distances ⟨Pb2-Pb2⟩ and ⟨Pb2-O4⟩ do not change considerably with the degree of substitution. This implies control of the substitution by not only spatial and charge accommodation of REE ions but also the availability of a stereochemically active 6s(2) electron pair on Pb(2+). The high-temperature electrical conductivity shows dependence on the degree of substitution with a minimum at x = 0.2 indicative of a possible change of the type of conductivity.

Enhancing the Bioactivity of Yttria-Stabilized Tetragonal Zirconia Ceramics via Grain-Boundary Activation.

PubMed

Ke, Jinhuan; He, Fupo; Ye, Jiandong

2017-05-17

Yttria-stabilized tetragonal zirconia (Y-TZP) has been proposed as a potential dental implant because of its good biocompatibility, excellent mechanical properties, and distinctive aesthetic effect. However, Y-TZP cannot form chemical bonds with bone tissue because of its biological inertness, which affects the reliability and long-term efficacy of Y-TZP implants. In this study, to improve the bioactivity of Y-TZP ceramics while maintaining their good mechanical performance, Y-TZP was modified by grain-boundary activation via the infiltration of a bioactive glass (BG) sol into the surface layers of Y-TZP ceramics under different negative pressures (atmospheric pressure, -0.05 kPa, and -0.1 kPa), followed by gelling and sintering. The in vitro bioactivity, mechanical properties, and cell behavior of the Y-TZP with improved bioactivity were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), electron probe microanalysis (EPMA), and Raman spectroscopy. The results of the bioactivity test conducted by immersing Y-TZP in simulated body fluid (SBF) showed that a bonelike apatite layer was produced on the entire surface. The mechanical properties of the modified Y-TZP decreased as the negative pressure in the BG-infiltration process increased relative to those of the Y-TZP blank group. However, the samples infiltrated with the BG sol under -0.05 kPa and atmospheric pressure still retained good mechanical performance. The cell-culture results revealed that the bioactive surface modification of Y-TZP could promote cell adhesion and differentiation. The present work demonstrates that the bioactivity of Y-TZP can be enhanced by grain-boundary activation, and the bioactive Y-TZP is expected to be a potential candidate for use as a dental implant material.

Mechanical behavior and failure analysis of prosthetic retaining screws after long-term use in vivo. Part 2: Metallurgical and microhardness analysis.

PubMed

Al Jabbari, Youssef; Fournelle, Raymond; Ziebert, Gerald; Toth, Jeffrey; Iacopino, Anthony

2008-04-01

This study involved testing and analyzing multiple retrieved prosthetic retaining screws after long-term use in vivo to: (1) detect manufacturing defects that could affect in-service behavior; (2) characterize the microstructure and alloy composition; and (3) further characterize the wear mechanism of the screw threads. Two new (control) screws from Nobel Biocare (NB) and 18 used (in service 18-120 months) retaining screws [12 from NB and 6 from Sterngold (SG)] were: (1) metallographically examined by light microscopy and scanning electron microscopy (SEM) to determine the microstructure; (2) analyzed by energy dispersive X-ray (EDX) microanalysis to determine the qualitative and semiquantitative average alloy and individual phase compositions; and (3) tested for Vickers microhardness. Examination of polished longitudinal sections of the screws using light microscopy revealed a significant defect in only one Group 4 screw. No significant defects in any other screws were observed. The defect was considered a "seam" originating as a "hot tear" during original casting solidification of the alloy. Additionally, the examination of longitudinal sections of the screws revealed a uniform homogeneous microstructure in some groups, while in other groups the sections exhibited rows of second phase particles. The screws for some groups demonstrated severe deformation of the lower threads and the bottom part of the screw leading to the formation of crevices and grooves. Some NB screws were comprised of Au-based alloy with Pt, Cu, and Ag as alloy elements, while others (Groups 4 and 19) were Pd-based with Ga, Cu, and Au alloy elements. The microstructure was homogeneous with fine or equiaxed grains for all groups except Group 4, which appeared inhomogeneous with anomalous grains. SG screws demonstrated a typical dendritic structure and were Au-based alloy with Cu and Ag alloy elements. There were differences in the microhardness of gold alloy screws from NB and SG as well as palladium alloy screws from NB. Significant differences within NB retaining screws and between NB and SG screws were found for microstructure, major alloy constituents, and microhardness.

Advanced STEM microanalysis of bimetallic nanoparticle catalysts

NASA Astrophysics Data System (ADS)

Lyman, Charles E.; Dimick, Paul S.

2012-05-01

Individual particles within bimetallic nanoparticle populations are not always identical, limiting the usefulness of bulk analysis techniques such as EXAFS. The scanning transmission electron microscope (STEM) is the only instrument able to characterize supported nanoparticle populations on a particle-by-particle basis. Quantitative elemental analyses of sub-5-nm particles reveal phase separations among particles and surface segregation within particles. This knowledge can lead to improvements in bimetallic catalysts. Advanced STEMs with field-emission guns, aberration-corrected optics, and efficient signal detection systems allow analysis of sub-nanometer particles.

Spectrum simulation in DTSA-II.

PubMed

Ritchie, Nicholas W M

2009-10-01

Spectrum simulation is a useful practical and pedagogical tool. Particularly with complex samples or trace constituents, a simulation can help to understand the limits of the technique and the instrument parameters for the optimal measurement. DTSA-II, software for electron probe microanalysis, provides both easy to use and flexible tools for simulating common and less common sample geometries and materials. Analytical models based on (rhoz) curves provide quick simulations of simple samples. Monte Carlo models based on electron and X-ray transport provide more sophisticated models of arbitrarily complex samples. DTSA-II provides a broad range of simulation tools in a framework with many different interchangeable physical models. In addition, DTSA-II provides tools for visualizing, comparing, manipulating, and quantifying simulated and measured spectra.

Metal and silicate particles including nanoparticles are present in electronic cigarette cartomizer fluid and aerosol.

PubMed

Williams, Monique; Villarreal, Amanda; Bozhilov, Krassimir; Lin, Sabrina; Talbot, Prue

2013-01-01

Electronic cigarettes (EC) deliver aerosol by heating fluid containing nicotine. Cartomizer EC combine the fluid chamber and heating element in a single unit. Because EC do not burn tobacco, they may be safer than conventional cigarettes. Their use is rapidly increasing worldwide with little prior testing of their aerosol. We tested the hypothesis that EC aerosol contains metals derived from various components in EC. Cartomizer contents and aerosols were analyzed using light and electron microscopy, cytotoxicity testing, x-ray microanalysis, particle counting, and inductively coupled plasma optical emission spectrometry. The filament, a nickel-chromium wire, was coupled to a thicker copper wire coated with silver. The silver coating was sometimes missing. Four tin solder joints attached the wires to each other and coupled the copper/silver wire to the air tube and mouthpiece. All cartomizers had evidence of use before packaging (burn spots on the fibers and electrophoretic movement of fluid in the fibers). Fibers in two cartomizers had green deposits that contained copper. Centrifugation of the fibers produced large pellets containing tin. Tin particles and tin whiskers were identified in cartridge fluid and outer fibers. Cartomizer fluid with tin particles was cytotoxic in assays using human pulmonary fibroblasts. The aerosol contained particles >1 µm comprised of tin, silver, iron, nickel, aluminum, and silicate and nanoparticles (<100 nm) of tin, chromium and nickel. The concentrations of nine of eleven elements in EC aerosol were higher than or equal to the corresponding concentrations in conventional cigarette smoke. Many of the elements identified in EC aerosol are known to cause respiratory distress and disease. The presence of metal and silicate particles in cartomizer aerosol demonstrates the need for improved quality control in EC design and manufacture and studies on how EC aerosol impacts the health of users and bystanders.

Selective binding of Ca2+, Zn2+, Cu2+ and K+ by the physodes of the green alga Mougeotia scalaris.

PubMed

Tretyn, A; Grolig, F; Magdowski, G; Wagner, G

1996-01-01

Cells of the zygnematophycean green alga Mougeotia contain numerous globules with polyphenolic matrix, which resemble physodes. In order to analyse the capability of this compartment to sequester various ions, trichomes of Mougeotia scalaris were either fixed for X-ray microanalysis simultaneously in 2% glutardialdehyde/1% OsO4 in phosphate buffers of different K+/Na(+)-ratios, or embedded directly (fresh material) in Nanoplast resin. In addition, fixed material was treated with potassium antimonate and Ca2+ localization was examined by electron microscopic cytochemistry. A Ca(2+)-depletion upon fixation at different K+/Na(+)-ratios resulted in selective uptake of potassium, but not sodium. Consistent with earlier findings, calcium-binding by the polyphenolic physode matrix does not depend merely on electric charge but also on the presence of protonated/deprotonated phenolic groups, together with ester-linked carbonyl oxygen, which seem to be good candidates for a co-ordinate type of calcium-binding. Nanoplast embedding turned out to be the most adequate and fastest preparation for X-ray microanalysis and, apart from retaining calcium, allowed the detection of zinc and copper inside the physodes.

Sample Preparation for Electron Probe Microanalysis—Pushing the Limits

PubMed Central

Geller, Joseph D.; Engle, Paul D.

2002-01-01

There are two fundamental considerations in preparing samples for electron probe microanalysis (EPMA). The first one may seem obvious, but we often find it is overlooked. That is, the sample analyzed should be representative of the population from which it comes. The second is a direct result of the assumptions in the calculations used to convert x-ray intensity ratios, between the sample and standard, to concentrations. Samples originate from a wide range of sources. During their journey to being excited under the electron beam for the production of x rays there are many possibilities for sample alteration. Handling can contaminate samples by adding extraneous matter. In preparation, the various abrasives used in sizing the sample by sawing, grinding and polishing can embed themselves. The most accurate composition of a contaminated sample is, at best, not representative of the original sample; it is misleading. Our laboratory performs EPMA analysis on customer submitted samples and prepares over 250 different calibration standards including pure elements, compounds, alloys, glasses and minerals. This large variety of samples does not lend itself to mass production techniques, including automatic polishing. Our manual preparation techniques are designed individually for each sample. The use of automated preparation equipment does not lend itself to this environment, and is not included in this manuscript. The final step in quantitative electron probe microanalysis is the conversion of x-ray intensities ratios, known as the “k-ratios,” to composition (in mass fraction or atomic percent) and/or film thickness. Of the many assumptions made in the ZAF (where these letters stand for atomic number, absorption and fluorescence) corrections the localized geometry between the sample and electron beam, or takeoff angle, must be accurately known. Small angular errors can lead to significant errors in the final results. The sample preparation technique then becomes very important, and, under certain conditions, may even be the limiting factor in the analytical uncertainty budget. This paper considers preparing samples to get known geometries. It will not address the analysis of samples with irregular, unprepared surfaces or unknown geometries. PMID:27446757

Electron-probe microanalysis of light elements in coal and other kerogen

USGS Publications Warehouse

Bustin, R.M.; Mastalerz, Maria; Raudsepp, M.

1996-01-01

Recent advances in electron microprobe technology including development of layered synthetic microstructures, more stable electronics and better matrix-correction programs facilitated routine microanalysis of the light elements in coal. Utilizing an appropriately equipped electron microprobe with suitable standards, it is now possible to analyze directly the light elements (C, O and N, if abundant) in coal macerals and other kerogen. The analytical results are both accurate compared to ASTM methods and highly precise, and provide an opportunity to access the variation in coal chemistry at the micrometre scale. Our experiments show that analyses using a 10 kV accelerating voltage and 10 nA beam current yield the most reliable data and result in minimum sample damage and contamination. High sample counts were obtained for C, O and N using a bi-elemental nickel-carbon pseudo-crystal (2d = 9.5 nm) as an analyzing crystal. Vitrinite isolated from anthracite rank coal proves the best carbon standard and is more desirable than graphite which has higher porosity, whereas lower rank vitrinite is too heterogeneous to use routinely as a standard. Other standards utilized were magnesite for oxygen and BN for nitrogen. No significant carbon, oxygen or nitrogen X-ray peak shifts or peak-shape changes occur between standards and the kerogen analyzed. Counting rates for carbon and oxygen were found to be constant over a range of beam sizes and currents for counting times up to 160 s. Probe-determined carbon and oxygen contents agree closely with those reported from ASTM analyses. Nitrogen analyses compare poorly to ASTM values which probably is in response to overlap between the nitrogen Ka peak with the carbon K-adsorption edge and the overall low nitrogen content of most of our samples. Our results show that the electron microprobe technique provides accurate compositional data for both minor and major elements in coal without the necessity and inherent problems associated with mechanically isolating macerals. Studies to date have demonstrated the level of compositional variability within and between macerals in suites of Canadian coals.

Cathodoluminescence, laser ablasion inductively coupled plasma mass spectrometry, electron probe microanalysis and electron paramagnetic resonance analyses of natural sphalerite

USGS Publications Warehouse

Karakus, M.; Hagni, R.D.; Koenig, A.; Ciftc, E.

2008-01-01

Natural sphalerite associated with copper, silver, lead-zinc, tin and tungsten deposits from various world-famous mineral deposits have been studied by cathodoluminescence (CL), laser ablasion inductively coupled plasma mass spectrometry (LA-ICP-MS), electron probe microanalysis (EPMA) and electron paramagnetic resonance (EPR) to determine the relationship between trace element type and content and the CL properties of sphalerite. In general, sphalerite produces a spectrum of CL colour under electron bombardment that includes deep blue, turquoise, lime green, yellow-orange, orange-red and dull dark red depending on the type and concentration of trace quantities of activator ions. Sphalerite from most deposits shows a bright yellow-orange CL colour with ??max centred at 585 nm due to Mn2+ ion, and the intensity of CL is strongly dependent primarily on Fe2+ concentration. The blue emission band with ??max centred at 470-490 nm correlates with Ga and Ag at the Tsumeb, Horn Silver, Balmat and Kankoy mines. Colloform sphalerite from older well-known European lead-zinc deposits and late Cretaceous Kuroko-type VMS deposits of Turkey shows intense yellowish CL colour and their CL spectra are characterised by extremely broad emission bands ranging from 450 to 750 nm. These samples are characterised by low Mn (<10 ppm) and Ag (<1 ppm), and they are enriched in Tl (1-30 ppm) and Pb (80-1500 ppm). Strong green CL is produced by sphalerite from the Balmat-Edwards district. Amber, lime-green and red-orange sphalerite produced weak orange-red CL at room temperatures, with several emission bands centred at 490, 580, 630, 680, 745, with ??max at 630 nm being the strongest. These emission bands are well correlated with trace quantities of Sn, In, Cu and Mn activators. Sphalerite from the famous Ogdensburg and Franklin mines exhibited brilliant deep blue and orange CL colours and the blue CL may be related to Se. Cathodoluminescence behaviour of sphalerite serves to characterise ore types and help detect technologically important trace elements.

Apparatus enables automatic microanalysis of body fluids

NASA Technical Reports Server (NTRS)

Soffen, G. A.; Stuart, J. L.

1966-01-01

Apparatus will automatically and quantitatively determine body fluid constituents which are amenable to analysis by fluorometry or colorimetry. The results of the tests are displayed as percentages of full scale deflection on a strip-chart recorder. The apparatus can also be adapted for microanalysis of various other fluids.

Platinum replica electron microscopy: Imaging the cytoskeleton globally and locally.

PubMed

Svitkina, Tatyana M

2017-05-01

Structural studies reveal how smaller components of a system work together as a whole. However, combining high resolution of details with full coverage of the whole is challenging. In cell biology, light microscopy can image many cells in their entirety, but at a lower resolution, whereas electron microscopy affords very high resolution, but usually at the expense of the sample size and coverage. Structural analyses of the cytoskeleton are especially demanding, because cytoskeletal networks are unresolvable by light microscopy due to their density and intricacy, whereas their proper preservation is a challenge for electron microscopy. Platinum replica electron microscopy can uniquely bridge the gap between the "comfort zones" of light and electron microscopy by allowing high resolution imaging of the cytoskeleton throughout the entire cell and in many cells in the population. This review describes the principles and applications of platinum replica electron microscopy for studies of the cytoskeleton. Copyright © 2017 Elsevier Ltd. All rights reserved.

Platinum Replica Electron Microscopy: Imaging the Cytoskeleton Globally and Locally

PubMed Central

SVITKINA, Tatyana M.

2017-01-01

Structural studies reveal how smaller components of a system work together as a whole. However, combining high resolution of details with full coverage of the whole is challenging. In cell biology, light microscopy can image many cells in their entirety, but at a lower resolution, whereas electron microscopy affords very high resolution, but usually at the expense of the sample size and coverage. Structural analyses of the cytoskeleton are especially demanding, because cytoskeletal networks are unresolvable by light microscopy due to their density and intricacy, whereas their proper preservation is a challenge for electron microscopy. Platinum replica electron microscopy can uniquely bridge the gap between the “comfort zones” of light and electron microscopy by allowing high resolution imaging of the cytoskeleton throughout the entire cell and in many cells in the population. This review describes the principles and applications of platinum replica electron microscopy for studies of the cytoskeleton. PMID:28323208

Genèse d'un horizon tacheté par déferruginisation dans une couverture à latérite du Bassin amazonien

NASA Astrophysics Data System (ADS)

Rosolen, Vania; Lamotte, Mathieu; Boulet, René; Trichet, Jean; Rouer, Olivier; José Melfi, Adolpho

A mottled horizon in a laterite cover (without any duricrust) was studied by microscopy and quantitative chemical microanalysis. Apart from the voids, light red spots consisting of Fe-rich particles (≈2 μm) are set in clayey plasma. Dark red spots consisted of concentrations of Fe-rich particles. These patterns are inherited. On the border of structural or biological voids, where Fe-depletion features are systematic, gray or yellow spots result from dissolution of the Fe-rich particles and impregnation of the plasma by iron, respectively. The present Fe-depletion is the dominant process that explains the mottled differentiation and the absence of lateritic duricrust. To cite this article: V. Rosolen et al., C. R. Geoscience 334 (2002) 187-195.

Silver stain for electron microscopy

NASA Technical Reports Server (NTRS)

Corbett, R. L.

1972-01-01

Ammoniacal silver stain used for light microscopy was adapted advantageously for use with very thin biological sections required for electron microscopy. Silver stain can be performed in short time, has more contrast, and is especially useful for low power electron microscopy.

Correlated Light and Electron Microscopy/Electron Tomography of Mitochondria In Situ

PubMed Central

Perkins, Guy A.; Sun, Mei G.; Frey, Terrence G.

2009-01-01

Three-dimensional light microscopy and three-dimensional electron microscopy (electron tomography) separately provide very powerful tools to study cellular structure and physiology, including the structure and physiology of mitochondria. Fluorescence microscopy allows one to study processes in live cells with specific labels and stains that follow the movement of labeled proteins and changes within cellular compartments but does not have sufficient resolution to define the ultrastructure of intracellular organelles such as mitochondria. Electron microscopy and electron tomography provide the highest resolution currently available to study mitochondrial ultrastructure but cannot follow processes in living cells. We describe the combination of these two techniques in which fluorescence confocal microscopy is used to study structural and physiologic changes in mitochondria within apoptotic HeLa cells to define the apoptotic timeframe. Cells can then be selected at various stages of the apoptotic timeframe for examination at higher resolution by electron microscopy and electron tomography. This is a form of “virtual” 4-dimensional electron microscopy that has revealed interesting structural changes in the mitochondria of HeLa cells during apoptosis. The same techniques can be applied, with modification, to study other dynamic processes within cells in other experimental contexts. PMID:19348881

Graphene-enabled electron microscopy and correlated super-resolution microscopy of wet cells.

PubMed

Wojcik, Michal; Hauser, Margaret; Li, Wan; Moon, Seonah; Xu, Ke

2015-06-11

The application of electron microscopy to hydrated biological samples has been limited by high-vacuum operating conditions. Traditional methods utilize harsh and laborious sample dehydration procedures, often leading to structural artefacts and creating difficulties for correlating results with high-resolution fluorescence microscopy. Here, we utilize graphene, a single-atom-thick carbon meshwork, as the thinnest possible impermeable and conductive membrane to protect animal cells from vacuum, thus enabling high-resolution electron microscopy of wet and untreated whole cells with exceptional ease. Our approach further allows for facile correlative super-resolution and electron microscopy of wet cells directly on the culturing substrate. In particular, individual cytoskeletal actin filaments are resolved in hydrated samples through electron microscopy and well correlated with super-resolution results.

Scanning ultrafast electron microscopy.

PubMed

Yang, Ding-Shyue; Mohammed, Omar F; Zewail, Ahmed H

2010-08-24

Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for which the pulse contains at most one or a few electrons, thus achieving imaging without the space-charge effect between electrons, and still in ten(s) of seconds. For imaging, the secondary electrons from surface structures are detected, as demonstrated here for material surfaces and biological specimens. By recording backscattered electrons, diffraction patterns from single crystals were also obtained. Scanning pulsed-electron microscopy with the acquired spatiotemporal resolutions, and its efficient heat-dissipation feature, is now poised to provide in situ 4D imaging and with environmental capability.

Au crystal growth on natural occurring Au-Ag aggregate elucidated by means of precession electron diffraction (PED)

NASA Astrophysics Data System (ADS)

Roqué Rosell, Josep; Portillo Serra, Joaquim; Aiglsperger, Thomas; Plana-Ruiz, Sergi; Trifonov, Trifon; Proenza, Joaquín A.

2018-02-01

In the present work, a lamella from an Au-Ag aggregate found in Ni-laterites has been examined using Transmission Electron Microscope to produce a series of Precision Electron Diffraction (PED) patterns. The analysis of the structural data obtained, coupled with Energy Dispersive X-ray microanalysis, made it possible to determine the orientation of twinned native gold growing on the Au-Ag aggregate. The native Au crystal domains are found to have grown at the outermost part of the aggregate whereas the inner core of the aggregate is an Au-Ag alloy (∼4 wt% Ag). The submicron structural study of the natural occurring Au aggregate points to the mobilization and precipitation of gold in laterites and provides insights on Au aggregates development at supergene conditions. This manuscript demonstrates the great potential of electron crystallographic analysis, and in particular, PED to study submicron structural features of micron sized mineral aggregates by using the example of a gold grain found in a Ni-laterite deposits.

High-Resolution of Electron Microscopy of Montmorillonite and Montmorillonite/Epoxy Nanocomposites

DTIC Science & Technology

2005-01-01

AFRL-ML-WP-TP-2006-464 HIGH-RESOLUTION OF ELECTRON MICROSCOPY OF MONTMORILLONITE AND MONTMORILLONITE /EPOXY NANOCOMPOSITES Lawrence F...HIGH-RESOLUTION OF ELECTRON MICROSCOPY OF MONTMORILLONITE AND MONTMORILLONITE /EPOXY NANOCOMPOSITES 5c. PROGRAM ELEMENT NUMBER 62102F 5d...transmission electron microscopy the structure and morphology of montmorillonite (MMT), a material of current interest for use in polymer nanocomposites, was

Assessing Language for Literacy: A Microanalysis of Children's Vocabulary, Syntax and Narrative Grammar

ERIC Educational Resources Information Center

Scull, Janet

2013-01-01

This paper examines the oral language resources that enhance children's reading and comprehension processes. Using data from a study of 16 children, the microanalysis of the three more successful readers, identified salient factors from the individual children's learning profiles that were observed as associated with their positive comprehension…

Correlative fluorescence microscopy and scanning transmission electron microscopy of quantum-dot-labeled proteins in whole cells in liquid.

PubMed

Dukes, Madeline J; Peckys, Diana B; de Jonge, Niels

2010-07-27

Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7x12 nm were visible in a 5 microm thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs.

Correlative Fluorescence Microscopy and Scanning Transmission Electron Microscopy of Quantum Dot Labeled Proteins in Whole Cells in Liquid

PubMed Central

Dukes, Madeline J.; Peckys, Diana B.; de Jonge, Niels

2010-01-01

Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid with fluorescence microscopy and with scanning transmission electron microscopy (STEM); there is no additional sample preparation necessary for the electron microscopy. Quantum dots (QDs) were bound to epidermal growth factor (EGF) receptors of COS7 fibroblast cells. Fixed whole cells in saline water were imaged with fluorescence microscopy and subsequently with STEM. The STEM images were correlated with fluorescence images of the same cellular regions. QDs of dimensions 7 × 12 nm were visible in a 5 μm thick layer of saline water, consistent with calculations. A spatial resolution of 3 nm was achieved on the QDs. PMID:20550177

Microfabricated ion trap array

DOEpatents

Blain, Matthew G [Albuquerque, NM; Fleming, James G [Albuquerque, NM

2006-12-26

A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

The effects of foliar fertilization with iron sulfate in chlorotic leaves are limited to the treated area. A study with peach trees (Prunus persica L. Batsch) grown in the field and sugar beet (Beta vulgaris L.) grown in hydroponics

PubMed Central

El-Jendoubi, Hamdi; Vázquez, Saúl; Calatayud, Ángeles; Vavpetič, Primož; Vogel-Mikuš, Katarina; Pelicon, Primož; Abadía, Javier; Abadía, Anunciación; Morales, Fermín

2014-01-01

Crop Fe deficiency is a worldwide problem. The aim of this study was to assess the effects of foliar Fe applications in two species grown in different environments: peach (Prunus persica L. Batsch) trees grown in the field and sugar beet (Beta vulgaris L. cv. “Orbis”) grown in hydroponics. The distal half of Fe-deficient, chlorotic leaves was treated with Fe sulfate by dipping and using a brush in peach trees and sugar beet plants, respectively. The re-greening of the distal (Fe-treated) and basal (untreated) leaf areas was monitored, and the nutrient and photosynthetic pigment composition of the two areas were also determined. Leaves were also studied using chlorophyll fluorescence imaging, low temperature-scanning electron microscopy microanalysis, scanning transmission ion microscopy-particle induced X-ray emission and Perls Fe staining. The distal, Fe-treated leaf parts of both species showed a significant increase in Fe concentrations (across the whole leaf volume) and marked re-greening, with significant increases in the concentrations of all photosynthetic pigments, as well as decreases in de-epoxidation of xanthophyll cycle carotenoids and increases in photochemical efficiency. In the basal, untreated leaf parts, Fe concentrations increased slightly, but little re-greening occurred. No changes in the concentrations of other nutrients were found. Foliar Fe fertilization was effective in re-greening treated leaf areas both in peach trees and sugar beet plants. Results indicate that the effects of foliar Fe-sulfate fertilization in Fe-deficient, chlorotic leaves were minor outside the leaf surface treated, indicating that Fe mobility within the leaf is a major constraint for full fertilizer effectiveness in crops where Fe-deficiency is established and leaf chlorosis occurs. PMID:24478782

The effects of foliar fertilization with iron sulfate in chlorotic leaves are limited to the treated area. A study with peach trees (Prunus persica L. Batsch) grown in the field and sugar beet (Beta vulgaris L.) grown in hydroponics.

PubMed

El-Jendoubi, Hamdi; Vázquez, Saúl; Calatayud, Angeles; Vavpetič, Primož; Vogel-Mikuš, Katarina; Pelicon, Primož; Abadía, Javier; Abadía, Anunciación; Morales, Fermín

2014-01-01

Crop Fe deficiency is a worldwide problem. The aim of this study was to assess the effects of foliar Fe applications in two species grown in different environments: peach (Prunus persica L. Batsch) trees grown in the field and sugar beet (Beta vulgaris L. cv. "Orbis") grown in hydroponics. The distal half of Fe-deficient, chlorotic leaves was treated with Fe sulfate by dipping and using a brush in peach trees and sugar beet plants, respectively. The re-greening of the distal (Fe-treated) and basal (untreated) leaf areas was monitored, and the nutrient and photosynthetic pigment composition of the two areas were also determined. Leaves were also studied using chlorophyll fluorescence imaging, low temperature-scanning electron microscopy microanalysis, scanning transmission ion microscopy-particle induced X-ray emission and Perls Fe staining. The distal, Fe-treated leaf parts of both species showed a significant increase in Fe concentrations (across the whole leaf volume) and marked re-greening, with significant increases in the concentrations of all photosynthetic pigments, as well as decreases in de-epoxidation of xanthophyll cycle carotenoids and increases in photochemical efficiency. In the basal, untreated leaf parts, Fe concentrations increased slightly, but little re-greening occurred. No changes in the concentrations of other nutrients were found. Foliar Fe fertilization was effective in re-greening treated leaf areas both in peach trees and sugar beet plants. Results indicate that the effects of foliar Fe-sulfate fertilization in Fe-deficient, chlorotic leaves were minor outside the leaf surface treated, indicating that Fe mobility within the leaf is a major constraint for full fertilizer effectiveness in crops where Fe-deficiency is established and leaf chlorosis occurs.

Measuring zinc in biological nanovesicles by multiple analytical approaches.

PubMed

Piacenza, Francesco; Biesemeier, Antje; Farina, Marco; Piva, Francesco; Jin, Xin; Pavoni, Eleonora; Nisi, Lorenzo; Cardelli, Maurizio; Costarelli, Laura; Giacconi, Robertina; Basso, Andrea; Pierpaoli, Elisa; Provinciali, Mauro; Hwang, James C M; Morini, Antonio; di Donato, Andrea; Malavolta, Marco

2018-07-01

Exosomes are nanovesicles known to mediate intercellular communication. Although it is established that zinc ions can act as intracellular signaling factors, the measurement of zinc in circulating nanovesicles has not yet been attempted. Providing evidence of the existence of this zinc fraction and methods for its measurement might be important to advance our knowledge of zinc status and its relevance in diseases. Exosomes from 0.5 ml of either fresh or frozen human plasma were isolated by differential centrifugation. A morphological and dimensional evaluation at the nanoscale level was performed by atomic force microscopy (AFM) and Transmission Electron Microscopy (TEM). Energy Dispersive X-Ray Microanalysis (EDX) revealed the elemental composition of exosomes and their respective total Zinc content on a quantitative basis. The zinc mole fraction (in at%) was correlated to the phosphorous mole fraction, which is indicative for exosomal membrane material. Both fresh (Zn/P 0.09 ± 0.01) and frozen exosomes (Zn/P 0.08 ± 0.02) had a significant zinc content, which increased up to 1.09 ± 0.12 for frozen exosomes when treated with increasing amounts of zinc (100-500 μM; each p < 0.05). Interestingly, after zinc addition, the Calcium mole fractions decreased accordingly suggesting a possible exchange by zinc. In order to estimate the intra-exosomal labile zinc content, an Imaging Flow Cytometry approach was developed by using the specific membrane permeable zinc-probe Fluozin-3AM. A labile zinc content of 0.59 ± 0.27 nM was calculated but it is likely that the measurement may be affected by purification and isolation conditions. This study suggests that circulating nano-vesicular-zinc can represent a newly discovered zinc fraction in the blood plasma whose functional and biological properties will have to be further investigated in future studies. Copyright © 2018 Elsevier GmbH. All rights reserved.

Pb-Induced Avoidance-Like Chloroplast Movements in Fronds of Lemna trisulca L.

PubMed Central

Samardakiewicz, Sławomir; Krzeszowiec-Jeleń, Weronika; Bednarski, Waldemar; Jankowski, Artur; Suski, Szymon; Gabryś, Halina; Woźny, Adam

2015-01-01

Lead ions are particularly dangerous to the photosynthetic apparatus, but little is known about the effects of trace metals, including Pb, on regulation of chloroplast redistribution. In this study a new effect of lead on chloroplast distribution patterns and movements was demonstrated in mesophyll cells of a small-sized aquatic angiosperm Lemna trisulca L. (star duckweed). An analysis of confocal microscopy images of L. trisulca fronds treated with lead (15 μM Pb2+, 24 h) in darkness or in weak white light revealed an enhanced accumulation of chloroplasts in the profile position along the anticlinal cell walls, in comparison to untreated plants. The rearrangement of chloroplasts in their response to lead ions in darkness was similar to the avoidance response of chloroplasts in plants treated with strong white light. Transmission electron microscopy X-ray microanalysis showed that intracellular chloroplast arrangement was independent of the location of Pb deposits, suggesting that lead causes redistribution of chloroplasts, which looks like a light-induced avoidance response, but is not a real avoidance response to the metal. Furthermore, a similar redistribution of chloroplasts in L. trisulca cells in darkness was observed also under the influence of exogenously applied hydrogen peroxide (H2O2). In addition, we detected an enhanced accumulation of endogenous H2O2 after treatment of plants with lead. Interestingly, H2O2-specific scavenger catalase partly abolished the Pb-induced chloroplast response. These results suggest that H2O2 can be involved in the avoidance-like movement of chloroplasts induced by lead. Analysis of photometric measurements revealed also strong inhibition (but not complete) of blue-light-induced chloroplast movements by lead. This inhibition may result from disturbances in the actin cytoskeleton, as we observed fragmentation and disappearance of actin filaments around chloroplasts. Results of this study show that the mechanisms of the toxic effect of lead on chloroplasts can include disturbances in their movement and distribution pattern. PMID:25646776

Electron Microscopy.

ERIC Educational Resources Information Center

Beer, Michael

1980-01-01

Reviews technical aspects of structure determination in biological electron microscopy (EM). Discusses low dose EM, low temperature microscopy, electron energy loss spectra, determination of mass or molecular weight, and EM of labeled systems. Cites 34 references. (CS)

Effect of the conditions of REM microalloying of steel on the corrosion activity of nonmetallic inclusions

NASA Astrophysics Data System (ADS)

Movenko, D. A.; Kotel'nikov, G. I.; Pavlov, A. V.; Bytsenko, O. A.

2015-11-01

Experimental heats of low-alloy steel are performed under various conditions of rare-earth metal microalloying and aluminum and calcium deoxidation. Electron-probe microanalysis of nonmetallic inclusions and a metallographic investigation of a metal are used to show that, when interacting with water, nonmetallic cerium oxide inclusions do not form hydrates and, correspondingly, are not aggressive. When aluminum, calcium, and cerium additions are sequentially introduced into a melt, a continuous cerium oxide shell forms on calcium aluminates, protects corrosive nonmetallic inclusions against interaction with water, and weakens local metal corrosion.

Electroerosion micro- and nanopowders for the production of hard alloys

NASA Astrophysics Data System (ADS)

Latypov, R. A.; Ageeva, E. V.; Kruglyakov, O. V.; Latypova, G. R.

2016-06-01

The shape and the surface morphology of the powder particles fabricated by the electroerosion dispersion of tungsten-containing wastes in illuminating oil are studied. The hard alloy fabricated from these powder particles is analyzed by electron-probe microanalysis. The powder synthesized by the electroerosion dispersion of the wastes of sintered hard alloys is found to consist of particles of a spherical or elliptical shape, an irregular shape (conglomerates), and a fragment shape. It is shown that W, Ti, and Co are the main elements in the hard alloy fabricated from the powder synthesized by electroerosion dispersion in illuminating oil.

Imaging of endodontic biofilms by combined microscopy (FISH/cLSM - SEM).

PubMed

Schaudinn, C; Carr, G; Gorur, A; Jaramillo, D; Costerton, J W; Webster, P

2009-08-01

Scanning electron microscopy is a useful imaging approach for the visualization of bacterial biofilms in their natural environments including their medical and dental habitats, because it allows for the exploration of large surfaces with excellent resolution of topographic features. Most biofilms in nature, however, are embedded in a thick layer of extracellular matrix that prevents a clear identification of individual bacteria by scanning electron microscopy. The use of confocal laser scanning microscopy on the other hand in combination with fluorescence in situ hybridization enables the visualization of matrix embedded bacteria in multi-layered biofilms. In our study, fluorescence in situ hybridization/confocal laser scanning microscopy and scanning electron microscopy were applied to visualize bacterial biofilm in endodontic root canals. The resulting fluorescence in situ hybridization /confocal laser scanning microscopy and scanning electron microscopy and pictures were subsequently combined into one single image to provide high-resolution information on the location of hidden bacteria. The combined use of scanning electron microscopy and fluorescence in situ hybridization / confocal laser scanning microscopy has the potential to overcome the limits of each single technique.

Attempt to assess the infiltration of enamel made with experimental preparation using a scanning electron microscope.

PubMed

Skucha-Nowak, Małgorzata

2015-01-01

The resin infiltration technique, a minimally invasive method, involves the saturation, strengthening, and stabilization of demineralized enamel by a mixture of polymer resins without the need to use rotary tools or the risk of losing healthy tooth structures. To design and synthesize an experimental infiltrant with potential bacteriostatic properties.To compare the depth of infiltration of the designed experimental preparation with the infiltrant available in the market using a scanning electron microscope. Composition of the experimental infiltrant was established after analysis of 1H NMR spectra of the commercially available compounds that can penetrate pores of demineralized enamel. As the infiltrant should have bacteriostatic features by definition, an addition of 1% of monomer containing metronidazole was made. Thirty extracted human teeth were soaked in an acidic solution, which was to provide appropriate conditions for demineralization of enamel. Afterward, each tooth was divided along the coronal-root axis into two zones. One zone had experimental preparation applied to it (the test group), while the other had commercially available Icon (the control group). The teeth were dissected along the long axis and described above underwent initial observation with use of a Hitachi S-4200 scanning electron microscope. It was found that all samples contained only oxygen and carbon, regardless of the concentration of additions introduced into them. The occurrence of carbon is partially because it is a component of the preparation in question and partially because of sputtering of the sample with it. Hydrogen is also a component of the preparation, as a result of its phase composition; however, it cannot be detected by the EDS method. SEM, in combination with X-ray microanalysis, does not allow one to explicitly assess the depth of penetration of infiltration preparations into enamel.In order to assess the depth of penetration of infiltration preparations with use of X-ray microanalysis, it is recommended to introduce a contrast agent that is approved for use in dental materials, such as ytterbium III fluoride.