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Energy Dispersive X-ray (energy + dispersive_x-ray)
Terms modified by Energy Dispersive X-ray Selected AbstractsNovel synthesis of polyethylene,poly(dimethylsiloxane) copolymers with a metallocene catalystJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2004Andrés E. Ciolino Abstract Polyethylene,poly(dimethylsiloxane) copolymers were synthesized in solution from an ethylene monomer and an ,-vinyl poly(dimethylsiloxane) (PDMS) macromonomer at 363 and 383 K with EtInd2ZrCl2/methylaluminoxane as a catalyst. The copolymers obtained were characterized with Fourier transform infrared spectroscopy, 1H and 13C NMR, size exclusion chromatography, and differential scanning calorimetry. The rheological properties of the molten polymers were determined under dynamic shear flow tests at small-amplitude oscillations, whereas the physical arrangement of the phase domains was analyzed with scanning electron microscopy (SEM)/energy dispersive X-ray (EDX). The analysis of the catalyst activity and the resulting polymers supported the idea of PDMS blocks or chains grafted to polyethylene. The changes in the rheological behavior and the changes in the Fourier transform infrared and NMR spectra were in agreement with this proposal. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2462,2473, 2004 [source] Synthesis of morphologically different, metal absorbing aniline-formaldehyde polymers including micron-sized sphere using simple alcohols as morphology modifierJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Rik Rani Koner Abstract Aniline-formaldehyde condensate (AFC) is an amine functional group containing polymer. The sticky resinous nature of the polymer limits its usefulness. Synthesis of AFC in presence of methanol, isopropanol, t -butanol, n -octanol or glycerine formed solid cakes instead of resinous material. The scanning electron microscopic (SEM) picture of the polymer synthesized in presence of t -butanol shows the formation of micron sized spheroids while the presence of methanol, isopropanol, n -octanol and glycerine leads to amorphous polymer. The polymers were characterized with IR, MALDI-TOF mass and Energy Dispersive X-ray (EDAX) analysis. To probe the accessibility of the amine functional groups by external reagents and as an application, metal removal property of the polymers were tested using aqueous Cr(VI) solution. All the polymers remove Cr(VI) efficiently at pH 3 with extent of metal removal depends on their morphology. Polymer synthesized in presence of isopropanol removes , 66% Cr(VI) removal from an initial concentration of 9 mg/L. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Rare earth ions in porous silicon: optical propertiesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2007H. Elhouichet Abstract Porous silicon (PS) is doped with rare earth (RE) ions (Er, Eu, Tb) by electrochemical anodisation. The penetration of RE into the PS layer is confirmed by Rutherford Backscattering Spectroscopy (RBS) and by Energy Dispersive X-ray (EDX) measurements. Efficient visible and infrared emissions were observed at room temperature. The activation temperatures of Eu, Tb and Er in PS are determined from the effect of thermal annealing on the photoluminescence (PL) intensity. From the evolution of the PL intensity versus temperature, it was found that a RE related level defect can be involved on the excitation and emission processes. Pump intensity dependent PL studies revealed that for the electrochemical incorporation, most of the RE ions are localized inside the Si nanocrystallites and not in stochiometric SiO2. The optical cross section is close to that of erbium in Si nanocrystallites. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sulphur, thiols, and disulphides in the fish epidermis, with remarks on keratinizationJOURNAL OF FISH BIOLOGY, Issue 4 2007W. Meyer Energy dispersive x-ray (EDX) analysis and qualitative and quantitative histochemistry were applied to study the distribution and contents of sulphur, thiols and disulphides in the epidermis of the river lamprey Lampetra fluviatilis, the lesser spotted dogfish Scyliorhinus canicula and the brown trout Salmo trutta fario. Thiols generally reacted weakly throughout the entire epidermis, whereas disulphide reactions were more distinct and differentiated. In the river lamprey, the concentrations of -S-S- groups clearly increased in the developing mucous cells from the stratum basale to the stratum superficiale; skein cells and granular cells reacted negatively to weakly. In the lesser spotted dogfish, amounts of disulphides appeared at moderate concentrations, and only goblet cells displayed a strong reaction. In the brown trout, filament cells showed low concentrations or weak reactions of disulphides, goblet cells and the most outer superficial cells stained strongly. Sulphur distribution and contents generally supported the histochemical observations in normal epidermis cells (absolute sulphur contents: 41,59 mM), only the brown trout showed high amounts of sulphur in the stratum basale (81 mM). The findings corroborate the view that there is an inverse correlation between keratinization and mucous secretion in normal fish epidermis. The sometimes distinct contents of disulphides in the outer mucous layer indicate that this system could endure higher mechanical stress than predictable from its large amounts of neutral glycoproteins. [source] Concentric Sub-micrometer-Sized Cables Composed of Ni Nanowires and Sub-micrometer-Sized Fullerene Tubes,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2007F. Tao Abstract Highly ordered arrays of submicrometer-sized coaxial cables composed of submicrometer-sized C60 and C70 tubes filled with Ni nanowires are successfully prepared by combining a sol,gel method with an electrodeposition process. The wall thickness of the submicrometer-sized tubes can be adjusted by the concentration of fullerenes and the immersion time. The thermal stability of the submicrometer-sized C60 tubes is studied by Raman spectroscopy and it is found that these structures can be easily decomposed to form carbon nanotubes at relatively low temperatures (above 573,K) in an alumina template. These novel coaxial cable structures have been characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), scanning electron microscopy (SEM), field-emission SEM (FESEM), Raman spectroscopy, elemental mapping, energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) experiments, and superconducting quantum interference device (SQUID) measurements. Magnetic measurements show that these submicrometer-sized cables exhibit enhanced ferromagnetic behavior as compared to bulk nickel. Moreover, submicrometer-sized C70/Ni cables show uniaxial magnetic anisotropy with the easy magnetic axis being parallel to the long axis of the Ni nanowires. C70/Ni cables also exhibit a new magnetic transition at ca.,10,K in the magnetization,temperature (M,T) curve, which is not observed for the analogous C60/Ni structures. The origin of this transition is not yet clear, but might be related to interactions between the Ni nanowires and C70 molecules. There is no preferred magnetization axis in submicrometer-sized C60/Ni cables, which implies that the Ni nanocrystals have different packing modes in the two composites. These different crystalline packing modes lead to different magnetic anisotropy in the two composites, although the Ni nanocrystals have the same face-centered cubic (fcc) structure in both cases. [source] Apatite-forming ability (bioactivity) of ProRoot MTAINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2010M. G. Gandolfi Gandolfi MG, Taddei P, Tinti A, Prati C. Apatite-forming ability (bioactivity) of ProRoot MTA. International Endodontic Journal, 43, 917,929, 2010. Abstract Aim, Apatite-forming ability, considered as an index of bioactivity (bond-to-bone ability), was tested on ProRoot MTA cement after immersion in phosphate-containing solution (DPBS). Methodology, Disk samples were prepared and immersed in DPBS for 10 min, 5 h, 1 and 7 days. The cement surface was studied by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, by micro-Raman spectroscopy and by environmental scanning electron microscope with energy dispersive X-ray (ESEM-EDX) analyses. The pH of the storage solution was also investigated. Results, Spectroscopic analyses revealed calcium phosphate bands after 5-h immersion in DPBS. After 1 day, an even coating composed of apatite spherulites (0.1,0.8 micron diameter) was observed by ESEM/EDX. After 7 days, its thickness had increased. Apatite nucleation had already occurred after 5-h immersion. At this time, the presence of portlandite (i.e. Ca(OH)2, calcium hydroxide) on the cement surface was also observed; at longer times, this component was released into the medium, which underwent a remarkable pH increase. Conclusions, The study confirms the ability of ProRoot MTA to form a superficial layer of apatite within hours. The excellent bioactivity of ProRoot MTA might provide a significant clinical advantage over the traditional cements used for root-end or root-perforation repair. [source] Bioactivity of novel carboxymethyl chitosan scaffold incorporating MTA in a tooth modelINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2010R. Budiraharjo Budiraharjo R, Neoh KG, Kang ET, Kishen A. Bioactivity of novel carboxymethyl chitosan scaffold incorporating MTA in a tooth model. International Endodontic Journal, 43, 930,939, 2010. Abstract Aim, To characterise the bioactivity of a novel carboxymethyl chitosan (CMCS) scaffold with and without incorporating mineral trioxide aggregate (MTA) in a tooth model. Methodology, Cross-linked CMCS scaffold (CaC) and MTA-coated CaC (CaMT) scaffold were prepared by freeze-drying. The bioactivity of the scaffolds was tested in vitro in four different mineralisation solutions (bulk system) and ex vivo in simulated body fluid (SBF) in the tooth model. After mineralisation, the mineral deposits on the scaffolds were analysed using scanning electron microscopy, energy dispersive X-ray, and inductively coupled plasma mass spectroscopy. All data were statistically analysed using the two-sample t -test (P < 0.05). Results, Hydroxyapatite (HAP) deposition was observed on CaC and CaMT scaffolds after 1 week of mineralisation in the tooth model and in the bulk system. The deposition was significantly higher (P < 0.05) on CaMT scaffold than that on CaC scaffold. The amount of HAP formed in the tooth model was significantly lower (P < 0.05) than that in the bulk solution. Conclusions, The CMCS scaffolds are bioactive and capable of biomineralisation by forming HAP within a tooth model ex vivo. The bioactivity of the CMCS scaffold can be enhanced by incorporating MTA. [source] Influence of Structural Principles on the Mechanics of a Biological Fiber-Based Composite Material with Hierarchical Organization: The Exoskeleton of the Lobster Homarus americanusADVANCED MATERIALS, Issue 4 2009Helge-Otto Fabritius Abstract The cuticle of the lobster Homarus americanus is a nanocomposite, such as most structural biological materials. It consists of a matrix of chitin-protein fibers associated with various amounts of crystalline and amorphous calcium carbonate in the rigid parts of the body, and is organized hierarchically at all length scales. One prominent design principle found in the hierarchical structure of such biological fibrous composite materials is the twisted plywood structure. In the lobster cuticle, it is formed by superimposing and gradually rotating planes of parallel aligned chitin-protein fibers. To adjust the mechanical properties to the requirements on the macroscopic level, the spatial arrangement and the grade of mineralization of the fibers can be modified. A second design principle of lobster cuticle is its honeycomb-like structure, generated by the well-developed pore canal system, whose twisted ribbon-shaped canals penetrate the cuticle perpendicular to its surface. Due to the hierarchical structure, the mechanical properties of the lobster cuticle have to be investigated at different length scales, which is essential for the understanding of the structure,mechanical function relations of mineralized tissues (e.g., potentially also bone and teeth). In order to investigate the influence of the structural principles on the mechanical properties on the macroscopic scale miniaturized tensile, compression, and shear tests were carried out to obtain integral mechanical data. Characterization of the microstructure included scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) measurements. [source] An Environmentally Benign, Highly Efficient Catalytic Reduction of p -Nitrophenol using a Nano-Sized Nickel Catalyst Supported on Silica-AluminaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Islam Hamdy Abd El Maksod Abstract A green and effective method is reported for the reduction of p -nitrophenol to p -aminophenol using a nano-sized nickel catalyst supported on silica-alumina in the presence of hydrazine hydrate as an alternative source of hydrogen. It was found that nickel loaded on a silica-alumina support is a very effective catalyst in the hydrogenation of p -nitrophenol to p -aminophenol. Thus it attained 100% conversion in only 69 seconds instead of 260 seconds for commercial Raney nickel. In addition, the possibility to reuse it more than one time with great efficiency gives it another advantage over commercial Rainey nickel which cannot be used more than once. This economical and environmentally friendly method provides a potentially new approach for the synthesis of the intermediate product of paracetamol in industry, which overcomes the drawbacks of the known reduction methods. The prepared catalysts were fully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and electron spin resonance (ESR) tehniques. [source] Estimation of cobalt coating layer thickness on acicular Fe3O4 powder using HR-TEMJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2001Keitarou Sakai The thicknesses of cobalt coating layers grown on four different types of acicular Fe3O4 particles were estimated from the analysis of lattice images and from the determination of the Co depth profile using high-resolution transmission electron microscopy (HR-TEM) coupled with an energy dispersive X-ray (EDX) analysis system. It was observed that the coating thickness might vary with the crystallite size resulting from the growth mechanism of the coating layer. In this study, two different layer thicknesses, 40,Å and less than 10,Å, were evidenced for crystallite sizes of 390,Å and 350,Å, respectively. [source] Characterization and use of acid-activated montmorillonite-illite type of clay for lead(II) removalAICHE JOURNAL, Issue 9 2010John U. Kennedy Oubagaranadin Abstract The natural local deposits of montmorillonite-illite type of clay (MIC) were susceptible for acid activation. Raw clay was taken for experimentation, disintegrated on acid activation with sulfuric acid, which showed a particle size distribution. The montmorillonite and illite phases in the raw clay disappeared on acid activation and the activated clay, MIC(AA), showed with sodium-aluminum-silicate and beidellite phases apart from quartz (low) phase. The raw and acid-activated clays were characterized using X-ray powder diffractometry, X-ray fluorescence, Fourier transform infrared spectrometry, and energy dispersive X-ray, and their adsorption capacities were compared. When tested for adsorption of Pb(II) in aqueous solutions, the acid-activated clay showed about 50% increased adsorption than raw clay. Sips adsorption isotherm and pseudo-second-order kinetic models were found to be best for the batch adsorption data. Kinetic studies showed the existence of film diffusion and intraparticle diffusion. A two-stage batch adsorber was designed for the removal of Pb(II) from aqueous solutions. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Wear mechanisms in metal-on-metal bearings: The importance of tribochemical reaction layersJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2010Markus A. Wimmer Abstract Metal-on-metal (MoM) bearings are at the forefront in hip resurfacing arthroplasty. Because of their good wear characteristics and design flexibility, MoM bearings are gaining wider acceptance with market share reaching nearly 10% worldwide. However, concerns remain regarding potential detrimental effects of metal particulates and ion release. Growing evidence is emerging that the local cell response is related to the amount of debris generated by these bearing couples. Thus, an urgent clinical need exists to delineate the mechanisms of debris generation to further reduce wear and its adverse effects. In this study, we investigated the microstructural and chemical composition of the tribochemical reaction layers forming at the contacting surfaces of metallic bearings during sliding motion. Using X-ray photoelectron spectroscopy and transmission electron microscopy with coupled energy dispersive X-ray and electron energy loss spectroscopy, we found that the tribolayers are nanocrystalline in structure, and that they incorporate organic material stemming from the synovial fluid. This process, which has been termed "mechanical mixing," changes the bearing surface of the uppermost 50 to 200 nm from pure metallic to an organic composite material. It hinders direct metal contact (thus preventing adhesion) and limits wear. This novel finding of a mechanically mixed zone of nanocrystalline metal and organic constituents provides the basis for understanding particle release and may help in identifying new strategies to reduce MoM wear. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:436,443, 2010 [source] Mechanical Behavior and Failure Analysis of Prosthetic Retaining Screws after Long-Term Use In Vivo.JOURNAL OF PROSTHODONTICS, Issue 3 2008Microhardness Analysis, Part 2: Metallurgical Abstract Purpose: 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. Materials and Methods: 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. Results: 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. Conclusions: Significant differences within NB retaining screws and between NB and SG screws were found for microstructure, major alloy constituents, and microhardness. [source] Yellow pigments in painting: characterisation and UV laser-induced modificationsJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2009S. Acquaviva Abstract Artistic yellow pigments, commonly employed from antiquity, were investigated by morphological, spectrophotometric and compositional analyses. Namely, scanning electron microscopy,energy dispersive X-ray (SEM/EDX) characterisations and reflectance, attenuated total reflection,Fourier transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy were carried out on egg yolk tempera models to discriminate the pigments. The models were irradiated with excimer KrF (248 nm) laser at different working conditions, and the effects induced on colour were related to chemical and physical modifications through the same analyses, as a function of laser parameters. It came out that the effects on the pictorial layers are always related to the modifications of the binding medium and, in addition, the laser radiation induces dehydration and transformation of iron oxides in natural earths. Copyright © 2009 John Wiley & Sons, Ltd. [source] Video Microscopy for the Investigation of Gas Phase CopolymerizationMACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2005Daniela Ferrari Abstract Summary: Video microscopy as a tool for investigating olefin gas phase copolymerization is presented for the first time in this paper. The central theme of this work is the study of the comonomer effect shown by an unbridged metallocene catalyst supported on silica. By using video microscopy, it is possible to observe the increase in catalytic activity in terms of particle growth as well as monomer consumption. The observation that a more pronounced induction period in the particle growth profile is shown with increasing propylene concentration led us to investigate the copolymers obtained at different polymerization times using 13C NMR analysis and single particle energy dispersive X-ray (EDX mapping). This allowed us to adapt the "polymer growth and particle expansion model" to the copolymerization. Besides physical causes for the comonomer effect, we wanted to determine whether the catalyst structure plays an important role in the comonomer effect. To this end we investigated two metallocenes bearing the same long bridging unit but differing in the ligand bound to the zirconium center. One metallocene bears a cyclopentadienyl ring, while the other bears an indenyl group. From a close analysis of the 13C NMR, it is clear that both catalysts insert ethylene more easily then propylene, probably due to the long bridging unit that results in a narrower aperture angle of the ligand. In addition to this, the indenyl ligand does not allow the formation of propylene blocks even at high propylene concentration. Snapshot of the polymer particles taken after 165 min of ethylene-1-butene copolymerization with catalyst 1. [source] A comparative electrochemical study of commercial and model aluminium alloy (AA5050)MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 6 2009P. Premendra Abstract A comparative electrochemical study of commercially recycled AA5050 and model AA5050, in their as-cast state, is carried out to investigate the effect of recycling and furthermore the effect of trace elements like Pb, Cu, etc on electrochemical activation and filiform corrosion (FFC) susceptibility. A systematic combination of surface analytical techniques like scanning Kelvin probe force microscopy (SKPFM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) is used to study the composition and electrochemical behaviour of second phase particles. These results, together with localized breakdown measurements using the electrochemical micro-cell, elucidate the effect of recycling and the role played by trace elements in influencing the electrochemical behaviour of the alloy. [source] Commercial carbon nanotubes as heterogeneous catalysts in energy related applicationsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009J. Zhang Abstract We report the application of commercial carbon nanotubes (CNTs) in two important heterogeneously catalyzed reactions, i.e., NH3 decomposition and oxidative dehydrogenation of ethylbenzene (EB). For NH3 decomposition, CNTs were used as supports for Co,Mo nanoparticles. The structure of fresh and used catalysts was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and line-scan energy dispersive X-ray (EDX). Most of the nanoparticles are individually separated and the synergism mainly increases the long-term stability rather than the activity. For the oxidative dehydrogenation, the metal-free CNTs display a superior performance as compared to the Fe-doped CNTs. The outstanding results in both reactions predict an extremely promising future of commercial nanocarbons in modern catalysis. [source] Photoluminescence properties of erbium-doped amorphous gallium-germanium-selenium films fabricated by RF sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S1 2009Takahiko Imai Abstract Chalcogenide glasses have various useful features for optical devices such as a high refractive index, low-loss transmission in the mid-IR, and low phonon energies. The fabrication of thin films is important for use in waveguide applications and integrated photonics. In this work, we report the properties of vacuum deposited films of gallium-germanium-selenium glasses onto fused silica substrates by an RF magnetron sputtering technique (RF electric power of 40-250 W and growth rate of 0.01-2.1 ,m/min). The concentration of Er3+ ions is controlled by the number of sintered Er2S3 small plates on a target. Samples are shown to be in an amorphous-like state as measured by X-ray diffraction experiments. Film thicknesses are proportional to the RF sputtering power and sputtering time. The compositions of films obtained from energy dispersive X-ray (EDX) analysis. There are much dependent on the condition of the sputtering target, for example whether the target is in the bulk or powder-state. Photoluminescence (PL) spectrum, intensity, and lifetime at 1550 nm band are measured by excitation from a 973 nm laser. The PL band of the films has a similar shape to those of bulk glasses. The PL intensity increased with the RF electric power. The PL lifetime at the 1550 nm band of the film is about 1.8-2.6 ms; the latter values are similar to those of bulk samples. The results show that the RF sputtering is a potential method of fabrication for Er-doped GeGaSe thin films. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Microstructures, defects, and localization luminescence in InGaAsN alloy filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003F. Nakajima Abstract We studied the structural and optical properties of InxGa1,xAs1,yNy (x = 0.116, ,0.3 and y = 0,0.031) alloy films grown by low-pressure metalorganic vapour epitaxy (LP-MOVPE), performing high-resolution transmission electron microscopy (HRTEM) and photoluminescece (PL) measurements. The effects of rapid thermal annealing (RTA) at 700 °C under N2 ambient were also examined. The TEM images showed that with increasing In content, not only misfit dislocations near the InGaAsN/GaAs interface due to the large lattice mismatch with the GaAs subatrate, but also many defects in the InGaAsN layer due to the relaxation of local strain increased. From energy dispersive X-ray (EDX) analysis of the high In-content layers (x = 0.3,0.355), we found a significant In fluctuation in the InGaAsN layer. The PL peaks of In0.116Ga0.884As1,yNy (y = 0,0.031) measured at 7 K shifted to the high-energy side after RTA, while those of InxGa1,xAs1,yNy (x = ,0.3, y = 0,0.015) shifted unusually to the low-energy side. This unsual behavior of the high In-content layer after RTA may be attributed to the enlargement of quantum-dot-like regions, which are formed by the compositional fluctuation in microscopic scale. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Deterioration in mechanical properties of glass fiber-reinforced nylon 6,6 composites by aqueous calcium chloride mixture solutionsPOLYMER COMPOSITES, Issue 4 2009D. Manjula Dhevi In this article, nylon 6,6 (NY66) and glass fiber-(30 wt%) reinforced NY66 (GFNY66) specimens were immersed in various aqueous calcium chloride (aq. CaCl2) mixture solutions at different thermal conditions for varying intervals of time, and analyzed using attenuated total reflection-infrared (ATR-IR) spectroscopy, inductively coupled plasma (ICP), energy dispersive X-ray (EDX), gel permeation chromatography (GPC), and mechanical studies. ICP data revealed increasing concentration of absorbed Ca2+ ions with increasing immersion time resulting in disruption of intra- and intermolecular H-bonding as confirmed using ATR-IR results. From EDX data, the ratio of Ca2+ and Cl, ions absorbed by NY66 was calculated and found to follow its stoichiometric equivalence. GPC data exhibited less reduction in Mn and Mw for aq. CaCl2 -treated NY66 specimens suggesting the absence of any significant chemical degradation, but the occurrence of only physical changes involving H-bond breakage and the formation of new CO···Ca2+ dative bond in NY66 matrix. The mechanical properties of GFNY66 samples treated with various types of aq. CaCl2 solutions exhibited pronounced deterioration, possibly due to the interfacial failure between glass fiber and NY66 matrix. The results obtained from this study were quite useful toward understanding the degradation mechanism in NY66 and GFNY66 caused by various aq. CaCl2 mixture solutions, and will be helpful in improving the mechanical properties of recycled NY66. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] MOCVD of YF3 and Y1,xErxF3 Thin Films from Precursors Synthesized In Situ,CHEMICAL VAPOR DEPOSITION, Issue 6-7 2005G. Condorelli Abstract RE(hfac)3 precursors (RE = Y, Er and Hhfac=1,1,1,5,5,5-hexafluoroacetylacetonate) have been obtained in-situ in a metal-organic (MO) CVD reactor by vapor-solid reaction between Hhfac and powders of suitable mixtures of RE2O3 oxides. YF3 and Y1,xErxF3 (x , 0.2) ultra-thin films have been deposited over glass substrates under Ar/O2 environments. Fourier-transform infrared (FTIR) in-situ measurements have been used to identify the nature of the precursor species in the gas phase, as well as to investigate decomposition mechanisms which accompany the film growth. Deposition involves the breakdown of the metal,ligand bond, thus leading to free Hhfac ligands and fluorinated ketones. Films have been characterized by energy dispersive X-ray (EDX) microanalysis, grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). [source] Preparation of Pt,Ru Alloyed Thin Films Using a Single-Source CVD Precursor,CHEMICAL VAPOR DEPOSITION, Issue 3 2003S.-F. Huang Abstract Treatment of (dimethylaminomethyl)ruthenocene with cis -Pt(DMSO)2Cl2 led to the formation of a ruthenocenyl platinum complex [CpRu(,5 -C5H3CH2NMe2)Pt(DMSO)Cl] (1); subsequent treatment of 1 with [Na(hfac)] afforded an air-stable Pt,Ru complex [CpRu(,5 -C5H3CH2NMe2)Pt(hfac)] (2). Its volatility and other physical data relevant to CVD experiments were assessed by thermogravimetric analysis (TGA). The Pt,Ru thin films were then deposited at two deposition temperatures, 300,°C and 400,°C, using O2 as the reactive carrier gas. The as-deposited thin films were characterized using energy dispersive X-ray (EDX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Results indicated the formation of a homogeneous Pt,Ru solid solution at the lower deposition temperature. However, upon raising the temperature to 400,°C, phase separation between Pt and Ru occurred, which then induced the growth of RuO2 grains at the substrate surface and caused depletion of the alloy in ruthenium. The electrocatalytic activities of the films, in respect of methanol oxidation, were investigated, in half-cell experiments, by cyclic voltammetry. [source] | ||||||||||||||||||||||||||||||||||