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Energy Dispersive Spectroscopy (energy + dispersive_spectroscopy)
Selected AbstractsNano-characterization of Cast Structures by FIB-Tomography,ADVANCED ENGINEERING MATERIALS, Issue 1-2 2008F. Lasagni In this communication, the three dimensional architectures of different Al-Si-(Mg) alloys are analyzed using SEM (Scanning Electron Microscopy)/FIB (Focus Ion Beam), EDS (Energy Dispersive Spectroscopy)/FIB and SEM-EDS/FIB tomographic methods. Several aspects for the imaging and quantification of the results are discussed describing the advantages and limitations of the methods to resolve submicron structures. [source] Calcite microcrystals in the pineal gland of the human brain: First physical and chemical studiesBIOELECTROMAGNETICS, Issue 7 2002Simon Baconnier Abstract A new form of biomineralization has been studied in the pineal gland of the human brain. It consists of small crystals that are less than 20 ,m in length and that are completely distinct from the often observed mulberry-type hydroxyapatite concretions. A special procedure was developed for isolation of the crystals from the organic matter in the pineal gland. Cubic, hexagonal, and cylindrical morphologies have been identified using scanning electron microscopy. The crystal edges were sharp whereas their surfaces were very rough. Energy dispersive spectroscopy showed that the crystals contained only the elements calcium, carbon, and oxygen. Selected area electron diffraction and near infrared Raman spectroscopy established that the crystals were calcite. With the exception of the otoconia structure of the inner ear, this is the only known nonpathological occurrence of calcite in the human body. The calcite microcrystals are probably responsible for the previously observed second harmonic generation in pineal tissue sections. The complex texture structure of the microcrystals may lead to crystallographic symmetry breaking and possible piezoelectricity, as is the case with otoconia. It is believed that the presence of two different crystalline compounds in the pineal gland is biologically significant, suggesting two entirely different mechanisms of formation and biological functions. Studies directed toward the elucidation of the formation and functions, and possible nonthermal interaction with external electromagnetic fields are currently in progress. Bioelectromagnetics 23:488,495, 2002. © 2002 Wiley-Liss, Inc. [source] Micrometric single crystal germanates obtained using a double-spherical mirror furnaceCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004E. A. Juarez-Arellano Abstract Micro-crystals of two new compounds EuMnGe2O7 and SmMnGe2O7 were grown performing the flux method in a double-spherical mirror furnace. One valuable advantage of this system was that the heating profile could be modified easily adjusting lamp positions and orientation as well. The micrometric crystals were observed and analyzed for chemical composition by scanning electron microscopy and energy dispersive spectroscopy. This furnace is perfectly suitable to grow at low price, low temperature and short time new materials as a single crystal for basic research or to obtain raw material. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Where Does the Lithium Go?ADVANCED ENGINEERING MATERIALS, Issue 4 2010A Study of the Precipitates in the Stir Zone of a Friction Stir Weld in a Li-containing 2xxx Series Al Alloy The main strengthening precipitates of aluminum alloy 2198-T8, which are of the T1 phase, dissolve during friction stir welding, sending many Li atoms into solid solution. The stir zone precipitates are characterized using high-resolution transmission electron microscopy, energy dispersive spectroscopy, and selected area diffraction techniques to begin answering questions about the microstructural evolution and the relationship between microstructure and mechanical properties in friction stir welding of the next generation of lightweight Li-containing Al alloys. [source] Hydroxyapatite/Bioactive Glass Films Produced by a Sol,Gel Method: In Vitro BehaviorADVANCED ENGINEERING MATERIALS, Issue 11 2009Nihat C. Köseo Abstract Hydroxyapatite (HA) and HA/bioactive glass (49S) films were deposited on Si(100) substrates by a sol,gel dip-coating method. The microstructure and in vitro bioactivity of the films were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Polycrystalline HA and amorphous bioactive glass films were obtained after annealing at 600 and 400,°C, respectively. The crystallization temperature of HA was determined to be around 568,°C. The surfaces of the HA films were covered with an apatite layer consists of spherulites formed by nanosized needle-like aggregates after the soaking in simulated body fluid (SBF) for 10 days, while amorphous HA/bioactive glass surface was covered with larger spherical crystallites. Both XPS and EDS results obtained from HA/bioactive glass film, after soaking in SBF, showed increasing P amounts on the surface at the expense of Si. The higher density of the newly formed layer on HA/bioactive glass surface than that of the HA surface after 10 days of soaking was evidence of increased reaction rate and apatite forming ability when bioactive glass layer is present on the HA films. [source] Genetically Engineered Phage Fibers and Coatings for Antibacterial ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Joan Y. Mao Abstract Multifunctionality can be imparted to protein-based fibers and coatings via either synthetic or biological approaches. Here, potent antimicrobial functionality of genetically engineered, phage-based fibers and fiber coatings, processed at room temperature, is demonstrated. Facile genetic engineering of the M13 virus (bacteriophage) genome leverages the well-known antibacterial properties of silver ions to kill bacteria. Predominant expression of negatively charged glutamic acid (E3) peptides on the pVIII major coat proteins of M13 bacteriophage enables solution-based, electrostatic binding of silver ions and subsequent reduction to metallic silver along the virus length. Antibacterial fibers of micrometer-scale diameters are constructed from such an E3-modified phage via wet-spinning and glutaraldehyde-crosslinking of the E3-modified viruses. Silverization of the free-standing fibers is confirmed via energy dispersive spectroscopy and inductively coupled plasma atomic emission spectroscopy, showing ,0.61,µg cm,1 of silver on E3,Ag fibers. This degree of silverization is threefold greater than that attainable for the unmodified M13,Ag fibers. Conferred bactericidal functionality is determined via live,dead staining and a modified disk-diffusion (Kirby,Bauer) measure of zone of inhibition (ZoI) against Staphylococcus epidermidis and Escherichia coli bacterial strains. Live,dead staining and ZoI distance measurements indicate increased bactericidal activity in the genetically engineered, silverized phage fibers. Coating of Kevlar fibers with silverized E3 phage exhibits antibacterial effects as well, with relatively smaller ZoIs attributable to the lower degree of silver loading attainable in these coatings. Such antimicrobial functionality is amenable to rapid incorporation within fiber-based textiles to reduce risks of infection, biofilm formation, or odor-based detection, with the potential to exploit the additional electronic and thermal conductivity of fully silverized phage fibers and coatings. [source] Automated SEM/EDS Analysis of Airbag Residue.JOURNAL OF FORENSIC SCIENCES, Issue 1 2009II: Airbag Residue as a Source of Percussion Primer Residue Particles Abstract:, Automated scanning electron microscopy with energy dispersive spectroscopy has been used to analyze airbag residue particles. Analysis of airbag residue from some passenger side airbags revealed some residue particles which are consistent with gunshot residue (GSR) samples. The source of these particles was determined to be percussion primers used to initiate the chemical reaction for deployment. This article identifies some vehicles which contain this type of airbag and demonstrates the types of particles which could be misidentified as being GSR. The low numbers of GSR particles in among the large particle populations of zirconium and/or copper,cobalt particles, which are clearly airbag residue, allow the trained analysts to distinguish the correct source of this residue. Particles containing high aluminum levels, elevated levels of allowable elements in GSR particles, or the presence of elements that are rare in GSR particles stand out as indications that the particles are not GSR in origin. This study serves as a guide to analysts who perform particle analysis in forensic investigations. [source] Effect of different acid treatments on a porcelain surface1JOURNAL OF ORAL REHABILITATION, Issue 1 2001. Canay The objective of this study was to determine the effect of selected surface treatments on the surface texture of a feldspathic porcelain. The three different etchant treatments were, acidulated phosphate fluoride (APF) applied for 10 min and hydrofluoric acid (HF) applied for 1 and 4 min. After acid treatment, half of the specimens from each group were cleansed with water and others were subjected to ultrasonic cleaning and then dried. Half of the specimens cleansed with two different methods were treated with silane. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize the effects of such treatments. Etching with APF displays shallow patterns. Etching for 1 min with HF displays deep channels, pores and precipitates on the surface and as the etching time increased these channels were replaced by larger channels. EDS analyses show that the crystalline precipitates on the etched surfaces, which were not readily soluble in water, were the reaction products of Na, K, Ca, Al, etc. HF displayed a more roughened surface than the APF gel. However, the precipitates remain on the surface after acid application, they can only be removed by ultrasonic cleaning and cannot be removed by rinsing. [source] Raman spectroscopy of Bi-Te thin filmsJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2008V. Russo Abstract The deposition of micro- and nanocrystalline bismuth telluride thin films with tailored structure and composition is of interest in view of improving the well-known material thermoelectric properties. Only a few works exist that discuss Raman scattering of Bi2Te3 crystals and films, while a Raman characterization of other phases, i.e. other lesser known compounds of the Bi-Te system, such as tsumoite (BiTe) and pilsenite (Bi4Te3), is still completely lacking. We here present a Raman investigation of Bi-Te polycrystalline thin films with controlled structure (stoichiometry and growth orientation), morphology and phase composition, produced by nanosecond pulsed laser deposition. Interpretation of Raman spectra from Bi-Te films was supported by scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-Ray diffraction measurements, together with the predictions of the group theory. In this way, the first Raman characterization of Bi-rich phases (namely BiTe and Bi4Te3) has been obtained. For Bi-Te compositions characterized by a high Bi or Te content, Raman spectra reveal that segregation of elemental Bi or Te occurs. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis and Characterization of Bulk, Vitreous Cadmium Germanium ArsenideJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2009Bradley R. Johnson Cadmium germanium diarsenide glasses were synthesized in bulk form (,2.4 cm3) using procedures adapted from the literature. Several issues involved in the fabrication and quenching of amorphous CdGexAs2 (x=0.45, 0.65, 0.85, and 1.00, where x is the molar ratio of Ge to 1 mol of Cd) are described. An innovative processing route is presented to enable fabrication of high-purity, vitreous, crack-free ingots with sizes up to 10 mm diameter, and 30,40 mm long. Specimens from selected ingots were characterized using thermal analysis, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, particle-induced X-ray emission, Rutherford backscattering, secondary ion mass spectrometry, X-ray diffraction, density, and optical spectroscopy. Variations in properties as a function of processing conditions and composition are described. Results show that the density of defect states in the middle of the band gap and near the band edges can be decreased three ways: through suitable control of the processing conditions, by doping the material with hydrogen, and by increasing the concentration of Ge in the glass. [source] Cubic-Formation and Grain-Growth Mechanisms in Tetragonal Zirconia PolycrystalJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2003Koji Matsui The microstructure in Y2O3 -stabilized tetragonal zirconia polycrystal (Y-TZP) sintered at 1300°,1500°C was examined to clarify the role of Y3+ ions on grain growth and the formation of cubic phase. The grain size and the fraction of the cubic phase in Y-TZP increased as the sintering temperature increased. Both the fraction of the tetragonal phase and the Y2O3 concentration within the tetragonal phase decreased with increasing fraction of the cubic phase. Scanning transmission electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDS) measurements revealed that cubic phase regions in grain interiors in Y-TZP generated as the sintering temperature increased. High-resolution electron microscopy and nanoprobe EDS measurements revealed that no amorphous layer or second phase existed along the grain-boundary faces in Y-TZP and Y3+ ions segregated at their grain boundaries over a width of ,10 nm. Taking into account these results, it was clarified that cubic phase regions in grain interiors started to form from grain boundaries and the triple junctions in which Y3+ ions segregated. The cubic-formation and grain-growth mechanisms in Y-TZP can be explained using the grain boundary segregation-induced phase transformation model and the solute drag effect of Y3+ ions segregating along the grain boundary, respectively. [source] Microwave-Assisted Combustion Synthesis of Tantalum Nitride in a Fluidized BedJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2003Akhil Jain Combustion synthesis experiments in a fluidized bed have been conducted using nitrogen as the fluidizing gas for the formation of transition-metal nitrides that are potential replacements for traditional hydrodenitrogenation and hydrodesulfurization catalysts. The microwave-assisted ignition of reaction has been investigated for its potential to produce nitride overlayers on two different sizes of tantalum particle substrates. Various characterization techniques,X-ray diffractometry, energy dispersive spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy,have been used to study the presence of nitride overlayers. The results indicate that microwave assistance can permit controlled formation of tantalum nitride (Ta2N) overlayers. [source] Pitting corrosion on 316L pipes in terephthalic acid (TA) dryerMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 11 2009Y. Gong Abstract Grade 316L is a type of austenitic stainless steel with ultra-low carbon content and it exhibits superior corrosion resistance. However, pitting is always observed in 316L steel when it is exposed to media containing halide ions. In the present study, we found that in the presence of acetate acid (HAc) containing chloride or bromide ions, pitting occurred on the surface of the rotary steam pipes with the matrix material of 316L steel in terephthalic acid (TA) dryer. In order to identify the causes of the failure, metallographic structures and chemical compositions of the matrix material were inspected by an optical microscope (OM) and a photoelectric direct reading spectrometer. Beside these, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) as well as ion chromatography (IC) were used to analyze the micromorphologies of the corrosion pits and the chemical compositions of the corrosion deposits within them. Analysis of the results revealed the sources of halide ions and the factors accelerating the corrosion rate. Beside these, detailed mechanisms of pitting were discussed and six out of all the seven theoretical morphologies of pitting features were obtained in practice. [source] Capability of thermodynamic calculation in the development of alloys for deposition of corrosion-protection coatings via thermal sprayingMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 9 2007M. Born The capability of thermodynamic calculations for the development of materials for corrosion protection of steels via thermal spraying is illustrated in several practical examples. Although the thermodynamic calculations are usually performed for the equilibrium state, they can yield important information even about fast chemical reactions that are far from the equilibrium conditions. The relevance and reliability of thermodynamic calculations can be improved significantly if their results are complemented by chemical and microstructural analyses. In this contribution, details on the melting and alloying processes in technically relevant nickel-based alloys were obtained from the combination of the thermodynamic calculations, differential thermal analysis, local chemical analysis using scanning electron microscopy with energy dispersive spectroscopy of characteristic X-rays and X-ray diffraction analysis. Furthermore, the results of the thermodynamic calculations performed on nickel-based alloys clarified the role of individual chemical elements dissolved in the alloys for the corrosion resistance of the alloys and thus they contributed to the improvement of the chemical stability of these alloys during the chemical reaction with gaseous substances containing chlorine. [source] NiO-induced crystallization and optical characteristics of Li2O,CaF2,P2O5 glass systemPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2008G. Murali Krishna Abstract Li2O,CaF2,P2O5 glasses mixed with different concentrations of NiO (ranging from 0 mol% to 2.0 mol%) were crystallized. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy and differential thermal analysis. Studies were extended to optical absorption and magnetic susceptibility of these glass ceramic samples. The XRD and SEM studies reveal the presence of lithium phosphate, calcium phosphate and nickel phosphate crystal phases. The optical absorption studies together with magnetic susceptibility measurements indicate a gradual transformation of nickel ions from tetrahedral sites to octahedral sites (lasing sites) as the concentration of NiO is increased beyond 0.8 mol%. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Fabrication of dendrite-like Au nanostructures and their enhanced photoluminescence emissionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2007Ying Hu Abstract Special hierarchical dendrite-like Au (DLAu) nanostructures were fabricated facilely between the gaps of Au electrodes by an electrochemical method. The composition, morphology and crystallinity of the DLAu nanostructures were characterized using energy dispersive spectroscopy, field emission scanning electron microscopy and X-ray diffraction, respectively. The formation of these nanostructures is attributed to the distribution of the local electrical field between the Au electrodes and a diffusion-limited aggregation process. Photoluminescence (PL) having an emission peak near 530 nm is observed from these nanostructures, which is attributed to the recombination of the s,p band electrons near the Fermi energy with the d band holes in the DLAu nanostructures generated by optical excitation. We believe that such PL enhancement compared to a smooth Au film is due to the local-field enhancement from the surface plasmon resonance of the DLAu nanostructures. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comparative Studies on Mo,Cr,N and Al,Cr,N Coatings Obtained by PVD Dual Magnetron SputteringPLASMA PROCESSES AND POLYMERS, Issue S1 2009Yacine Benlatreche Abstract Recently, several studies have shown that the addition of a secondary element likes Al, Si, etc. to nitride and carbide binary systems such as Ti,N and Cr,N improved their structural and mechanical properties and also their thermal stability. In this study, we realized a comparison between the effects of aluminium or molybdenum addition on the properties of the Cr,N system. The (Cr,Al)N and (Cr,Mo)N films were deposited by RF dual magnetron sputtering. To control the aluminium and molybdenum contents in (Cr,Al)N and in (Cr,Mo)N films, respectively, we modified the Cr, Al and Mo target bias. The structural, morphological and composition analyses of the deposited films were carried out using X-ray diffraction (XRD) and SEM equipped with an energy dispersive spectroscopy (EDS) microanalysis. The variation of the residual stresses with the Al and Mo contents has been studied using the Newton's rings method. The obtained Al contents in (Cr,Al)N deposited films varied between 0 and 51,at.% while the Mo contents in (Cr,Mo)N layers varied between 0 and 42,at.%. A morphological change from amorphous to columnar films has been observed with the addition of Al in the case of (Cr,Al)N coatings, while all the (Cr,Mo)N films presented a columnar structure. The residual stresses of the (Cr,Mo)N coatings are higher than the (Cr,Al)N ones but they exhibited a similar behaviour for both coatings. [source] Use of recombinant rotavirus VP6 nanotubes as a multifunctional template for the synthesis of nanobiomaterials functionalized with metalsBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Germán Plascencia-Villa Abstract The structural characteristics and predefined constant size and shape of viral assemblies make them useful tools for nanobiotechnology, in particular as scaffolds for constructing highly organized novel nanomaterials. In this work it is shown for the first time that nanotubes formed by recombinant rotavirus VP6 protein can be used as scaffolds for the synthesis of hybrid nanocomposites. Rotavirus VP6 was produced by the insect cell-baculovirus expression vector system. Nanotubes of several micrometers in length and various diameters in the nanometer range were functionalized with Ag, Au, Pt, and Pd through strong (sodium borohydride) or mild (sodium citrate) chemical reduction. The nanocomposites obtained were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM) with energy dispersive spectroscopy (EDS), dynamic light scattering, and their characteristic plasmon resonance. The outer surface of VP6 nanotubes had intrinsic affinity to metal deposition that allowed in situ synthesis of nanoparticles. Furthermore, the use of preassembled recombinant protein structures resulted in highly ordered integrated materials. It was possible to obtain different extents and characteristics of the metal coverage by manipulating the reaction conditions. TEM revealed either a continuous coverage with an electrodense thin film when using sodium citrate as reductant or a discrete coverage with well-dispersed metal nanoparticles of diameters between 2 and 9,nm when using sodium borohydride and short reaction times. At long reaction times and using sodium borohydride, the metal nanoparticles coalesced and resulted in a thick metal layer. HRTEM-EDS confirmed the identity of the metal nanoparticles. Compared to other non-recombinant viral scaffolds used until now, the recombinant VP6 nanotubes employed here have important advantages, including a longer axial dimension, a dynamic multifunctional hollow structure, and the possibility of producing them massively by a safe and efficient bioprocess. Such characteristics confer important potential applications in nanotechnology to the novel nanobiomaterials produced here. Biotechnol. Bioeng. 2009; 104: 871,881. © 2009 Wiley Periodicals, Inc. [source] Characterization of Lead Precipitate Following Uptake by Roots of Brassica junceaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2009Donald E. R. Meyers Abstract Seedlings of Brassica juncea (L.) Czern. were grown in solution culture for 14 d prior to exposure to Pb2+ at an activity of 31 ,M for 72 h. Electron-dense deposits found within the apoplast and symplast were analyzed using scanning transmission electron microscopy/energy dispersive spectroscopy to determine the chemical identity of the deposits and potential toxicity resistance mechanisms. Irrespective of the cellular compartment in which they were found, the deposits contained Pb, O, P, and Cl. For the extracellular deposits, the average Pb:P:O atomic ratio was 1:0.54:3.0, which together with the hexagonal crystal system suggests that Pb is present as chloropyromorphite (Pb5(PO4)3Cl). A weak Ca signal also was detected in approximately half of the spectra, possibly indicating the presence of small concentrations of phosphohedyphane (Pb3Ca2(PO4)3Cl). The evidence suggests that B. juncea resists Pb toxicity by storing precipitated Pb in the vacuole. [source] | |||||||||||||||||||