Energy Dispersive X-ray Spectroscopy (energy + dispersive_x-ray_spectroscopy)

Distribution by Scientific Domains
Distribution within Chemistry


Selected Abstracts


Capacity Fading Mechanism in All Solid-State Lithium Polymer Secondary Batteries Using PEG-Borate/Aluminate Ester as Plasticizer for Polymer Electrolytes

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Fuminari Kaneko
Abstract Solid-state lithium polymer secondary batteries (LPB) are fabricated with a two-electrode-type cell construction of Li|solid-state polymer electrolyte (SPE)|LiFePO4. Plasticizers of poly(ethylene glycol) (PEG)-borate ester (B-PEG) or PEG-aluminate ester (Al-PEG) are added into lithium-conducting SPEs in order to enhance their ionic conductivity, and lithium bis-trifluoromethansulfonimide (LiTFSI) is used as the lithium salt. An improvement of the electrochemical properties is observed upon addition of the plasticizers at an operation temperature of 60,°C. However, a decrease of discharge capacities abruptly follows after tens of stable cycles. To understand the origin of the capacity fading, electrochemical impedance techniques, ex-situ NMR and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) techniques are adopted. Alternating current (AC) impedance measurements indicate that the decrease of capacity retention in the LPB is related to a severe increase of the interfacial resistance between the SPE and cathode. In addition, the bulk resistance of the SPE film is observed to accompany the capacity decay. Ex situ NMR studies combined with AC impedance measurements reveal a decrease of Li salt concentration in the SPE film after cycling. Ex situ SEM/EDS observations show an increase of concentration of anions on the electrode surface after cycling. Accordingly, the anions may decompose on the cathode surface, which leads to a reduction of the cycle life of the LPB. The present study suggests that a choice of Li salt and an increase of transference number is crucial for the realization of lithium polymer batteries. [source]


Natural and Prosthetic Heart Valve Calcification: Morphology and Chemical Composition Characterization

ARTIFICIAL ORGANS, Issue 4 2010
Raquel F. Weska
Abstract Calcification is the most common cause of damage and subsequent failure of heart valves. Although it is a common phenomenon, little is known about it, and less about the inorganic phase obtained from this type of calcification. This article describes the scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy and Ca K -edge X-ray absorption near edge structure (XANES) characterization performed in natural and bioprosthetic heart valves calcified in vivo (in comparison to in vitro-calcified valves). SEM micrographs indicated the presence of deposits of similar morphology, and XANES results indicate, at a molecular level, that the calcification mechanism of both types of valves are probably similar, resulting in formation of poorly crystalline hydroxyapatite deposits, with Ca/P ratios that increase with time, depending on the maturation state. These findings may contribute to the search for long-term efficient anticalcification treatments. [source]


Gadolinium-Induced Nephrogenic Systemic Fibrosis Is Associated with Insoluble Gd Deposits in Tissues: In Vivo Transmetallation Confirmed by Microanalysis

JOURNAL OF CUTANEOUS PATHOLOGY, Issue 12 2009
Charu Thakral
Background: Nephrogenic systemic fibrosis (NSF) is an extremely debilitating systemic fibrosing disorder affecting renal failure patients. The association of NSF with gadolinium (Gd) containing magnetic resonance contrast agents was noted in 2006. Gd deposition in skin biopsies was demonstrated shortly thereafter. Methods: We used automated scanning electron microscopy (SEM)/energy dispersive x-ray spectroscopy for in situ quantitative analysis of insoluble Gd-containing deposits, recording multi-elemental composition and spatial distribution of detected features. Results: Gd was detected in all 29 patients (53 of 57 skin biopsies) with NSF, biopsied from 2 weeks to 3 years after Gd exposure. Gd concentration ranged from 1 to 2270 cps/mm2 and was detected predominantly in the deep dermis and subcutaneous fibrous septa. Gd was found associated with Ca, P and sometimes Fe or Zn. Patients with sequential biopsies showed persistence or increase of Gd in tissues (6 of 11). Transmission electron microscopy (TEM) identified the intracellular deposits in fibrocytes and macrophages. Conclusions: The demonstration of insoluble tissue deposits of Gd with co-associated elements clearly confirms in vivo transmetallation and dissociation of soluble Gd-chelates. Toxic Gd3+ may trigger fibrosis under permissive conditions, e.g., in renal insufficiency. Pathologists and clinicians need to be aware of this serious but preventable disease. [source]


The effect of alloying elements on the crystallization behaviour and on the properties of galvanized coatings

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2004
G. Vourlias
Abstract The influence of the alloying elements on the interface reactions of zinc coatings during the galvanization process was examined. These reactions affect the crystallization and the structure and properties of the outer layer of the coatings. Depending on the type and concentration of the alloying additions in the galvanizing bath differences were induced in the crystallization process of the Fe-Zn phases. It was found that both the concentration and the distribution of the alloying elements played an important role in the growth of the phases. The formation of the phases and the distribution of the alloying elements in the coatings were determined using X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM) associated with an Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Finally the behaviour of the galvanized coatings was examined under accelerated salt spray corrosion conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Mechanical and tribological characterization of CNx films deposited by d.c. magnetron sputtering

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2007
L. Ipaz
Abstract Carbon nitride (CNx) thin films were deposited onto silicon and steel substrates at 400 °C from a carbon target by d.c. magnetron sputtering system. The composition, structural, and mechanical properties of deposited films were investigated as a function of argon/nitrogen concentration and sputtering power, by means of Energy Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy (RS), and nanoindentation. The EDS and Elastic Forward Analisys Analysis (EFA) showed that the nitrogen concentration in the CNx deposited films varied between 16% and 28% at depending on nitrogen concentrations in argon/nitrogen gas mixture, and deposition power. FTIR analysis indicated the presence of 2266 and 2278 cm,1 stretching peaks associated with CN triple bonds of nitriles and isocyanides, 1640 cm,1 and 1545 cm,1 associated with the C=C and C=N bonds. The thickness of the CNx deposited films varied between 0.4 and 0.8 µm at different sputtering powers. The hardness and Young's modulus were investigated by depth sensing nanoindentation method. The obtained hardness and Young's modulus increased from 4 to 17 GPa, and from 50 to 170 GPa, respectively; when the nitrogen content in the deposited films diminished between 28 and 12%. On the other hand, the friction and wear tests were done using a pin-on-disc tribometer. The friction tests showed values of 0.05 and 0.4 in dry air and humid atmosphere; respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Synthesis and characterization of styrene butadiene rubber,Bentonite clay nanocomposites

POLYMER ENGINEERING & SCIENCE, Issue 7 2009
Sugata Chakraborty
In the present study, naturally occurring unfractionated bentonite clay was used to prepare styrene butadiene rubber/bentonite clay nanocomposite by latex stage blending. The bentonite clay was organo-modified by in situ resol formation by the reaction of resorcinol and formaldehyde. The latex clay mixture was co-coagulated with acid. The resulting clay masterbatch was compounded and evaluated by Fourier Transform Infrared spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetric analysis, and Differential Scanning Calorimetry. XRD showed that the interplanar distance of the in situ resol-modified bentonite clay increased from 1.23 to 1.41 nm for the unmodified bentonite. TEM analysis indicated partial exfoliation and/or intercalation. EDS (Si and Al mapping) of the clay revealed the nature of the dispersion in the nanocomposites vis-à-vis the conventional styrene-butadiene rubber (SBR)/bentonite clay composite. Thermogravimetric analysis was used to compare the decomposition trends of the SBR/clay nanocomposites with the SBR/clay composite. The glass transition temperature of SBR/clay nanocomposites increased as compared with that of neat SBR. Substantial improvement in most of the other mechanical properties was also observed in case of the nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]


Filling of carbon nanotubes for bio-applications

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2007
S. Costa
Abstract Carbon nanotubes (CNT) provide a smart carrier system on the nanometer scale. The system can be used as a template for ferromagnetic fillers. Such a molecular hybrid is a promising potential candidate for the controlled heating of tumour tissue at the cellular level. This is a key reason why it is important to optimize the synthesis route of metal filled carbon nanotubes with regards bulk scale synthesis and purity. In the current study we present multiwalled carbon nanotubes filled with ,-iron phase (Fe-MWCNT). The influence of acid treatment on the stability of the filling and the sample purity is also presented. High resolution transmission microscopy, its Energy dispersive X-Ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) modes have been applied for the analysis of the morphology and chemical composition of the samples. The phase of iron nanowires encapsulated into the carbon nanotubes was determined with selected area electron diffraction (SAED) on a local scale. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Preparation and characterization of crosslinked resins containing ferrite particles

POLYMER ENGINEERING & SCIENCE, Issue 10 2008
Luiz Claudio de Santa Maria
Micrometer-sized magnetic particles hosted on network material were successfully prepared by a simple chemical process (ion exchange followed by co-precipitation) from commercial styrene-divinylbenzene copolymers. Energy dispersive X-ray spectroscopy (EDS) coupled to scanning electron microscopy (SEM) allowed the observation of submicron particles. All the produced spherical beads have presented metallic particles (NiFe2O4, CuFe2O4, CoFe2O4, or MnFe2O4), either as isolated particles or agglomerates, located on their external and internal (within pores) The thermal stability of the composites, evaluated by thermogravimetric techniques, were found to be dependent on the amount of ferrite particles incorporated into them. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers. [source]


Synthesis and Characterization of Single-Crystalline Lanthanum Fluoride with a Ring-Like Nanostructure

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2009
Yang Tian
Abstract LaF3 ring-like nanostructures with a diameter of less than 2 ,m have been fabricated by a facile, effective, and environmentally friendly molten salt synthesis route in which NaNO3 and KNO3 (2:1 molar ratio) act as reaction media and the rare-earth nitrate and NaF as precursor. X-ray diffraction, TEM, HR-TEM, energy dispersive X-ray spectroscopy, and photoluminescence spectroscopy are all used to characterize the as-prepared samples. Experiments peformed with different reaction times indicate that a central-etching of the plates from the inner part towards the edge during nanocrystal growth plays a key role in the formation of LaF3 nanorings since no other templates/surfactants are present in our system. Additionally, the luminescence properties of LaF3 nanorings doped with Eu3+ cation have been investigated andcompared with those of bulk materials and nanoparticles with a size of approximately 50 nm. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


Deposition of PtxRu1,x Catalysts for Methanol Oxidation in Micro Direct Methanol Fuel Cells

ISRAEL JOURNAL OF CHEMISTRY, Issue 3-4 2008
William E. Mustain
Platinum-ruthenium electrodes (PtxRu1-x) have been prepared by electrochemical and electroless deposition and investigated as catalysts for the oxidation of methanol in acidic solutions. PtxRu1-x deposits were electrochemically deposited from acidic chloride electrolytes at potentials between ,0.46 and 0.34 V (vs. NHE). The composition of the electrodeposit was estimated by energy dispersive X-ray spectroscopy and is a strong function of the electrode potential. An empirical model for the deposition process is presented and kinetic parameters are estimated and discussed. Also, the methanol oxidation activity of the PtxRu1-x catalysts was characterized by cyclic voltammetry in 1.0 M CH3OH, 1.0 M H2SO4 solutions. Electroless PtxRu1-x samples were prepared in a modified Leaman bath with hydrazine dihydrochloride as the reducing agent. The kinetic results for the electrochemical deposition of PtxRu1-x were directly applied and the deposition potential was estimated as approximately 0.40 V. [source]


Reducing ammonia emission from poultry manure composting via struvite formation

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2007
Wenxiu Zhang
Abstract Composting can provide a viable alternative for poultry manure management in the Fraser Valley of British Columbia, Canada. However, it has a high potential for ammonia emission because of the high nitrogen content of poultry litter. The objective of this study was to reduce ammonia emission by precipitating ammonia into struvite before it can volatilize from the composting matrix. Nitrogen transformation occurs during composting, but struvite formation can help to conserve nitrogen, and does not allow a large amount of nitrogen to be released into the environment as ammonia or nitrate, because ammonium-nitrogen becomes bound in struvite. It would also be possible to remove phosphorus from the manure. A laboratory-scale experiment was conducted to examine the feasibility of struvite formation during poultry manure composting. Magnesium and phosphate salts were supplemented to create favorable conditions to form struvite. Results indicated that ammonia emission was reduced by 40% to 84%, while the nitrogen retention in compost was enhanced. The struvite formed in compost was confirmed by means of X-ray diffraction; and scanning electron microscopy with energy dispersive X-ray spectroscopy. Copyright © 2007 Society of Chemical Industry [source]


Hybrid ZnAl-LDH/CNTs nanocomposites: Noncovalent assembly and enhanced photodegradation performance

AICHE JOURNAL, Issue 3 2010
Hui Wang
Abstract In this article, we reported a facile and effective strategy for assembling hybrid ZnAl-layered double hydroxide/carbon nanotubes (ZnAl-LDH/CNTs) nanocomposites through noncovalent bonds, for the first time, in the presence of L -cysteine molecules. The materials have been characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray photoelectron spectra (XPS) and specific surface area measurement. The results indicate that L -cysteine as bridging linker plays a key role for enhancing both adhesion and dispersion of LDH nanocrystallites onto the surface of CNTs matrix through the interfacial interaction, and effectively inhibits the in situ growth of LDH crystallites, thus resulting in remarkably reduced LDH crystallite sizes; the Eu(III) fluorescence quenching in intercalated-Eu(III)complex LDH/CNTs nanocomposite can occur because of the interaction between LDH crystallites and CNTs matrix. Furthermore, it is found that as-assembled hybrid LDH/CNTs nanocomposites exhibit excellent performance for photodegradation of methyl orange molecules under UV irradiation, which is closely related to the unique hybrid nanostructure and composition of composites. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]


Streaming potential characterization of LBL membranes on porous ceramic supports

AICHE JOURNAL, Issue 4 2007
Yiwei Chen
Abstract An in-situ characterization of the growth of the self-assembled polyelectrolyte membranes on the porous support was conducted by applying transmembrane streaming potential measurement via surface charge monitoring. The membranes were prepared by layer-by-layer alternative deposition of poly (allylamine hydrochloride) and poly (styrenesulfonate) on porous ceramic supports. The surface charge variations of membranes as functions of different top-assembled materials and numbers of deposited cycles were investigated. Different top-assembled materials make isoelectric points of the as-prepared membranes drift in opposite directions and also lead to symmetrical signal changes of zeta-potential in salt solutions at the isoelectric points of the supports. Ex-situ characterizations, including scanning electron microscopy, atomic force microscopy, and energy dispersive X-ray spectroscopy, also confirm the alternative deposition of polyelectrolytes. It is demonstrated that the transmembrane streaming potential measurement is effective in studying the growth of layer-by-layer membranes on porous support. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source]


Initial exploration of tribological performance of novel triazine derivatives in water

LUBRICATION SCIENCE, Issue 4 2009
Liping Sheng
Abstract Two novel ashless and non-phosphorus triazine derivatives, 2,4,6-tri-[N-hydroxyethyl-amino-methylenesulfanyl]-s-triazine and 2,4,6-tri-[N,N-bishydroxyethyl-amino-methylenesulfanyl]-s-triazine, were synthesised and their structures were analysed through elemental analysis. Their tribological behaviours in water were evaluated with a four-ball machine, and the results indicate that their wear resistance and load-carrying properties were excellent. The chemical features of the worn steel surface were observed and examined by means of inverted metallurgical microscopy and energy dispersive X-ray spectroscopy. The analytical results of typical elements on the worn steel surface demonstrated, during the lubricating process, that the additives reacted with counter-face metal and generated a boundary lubricating and protecting film containing elements of S, N and others, which contributes to improve the tribological properties of the test fluid. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Microstructural study of micron-sized craters simulating Stardust impacts in aluminum 1100 targets

METEORITICS & PLANETARY SCIENCE, Issue 2 2006
Hugues Leroux
First, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to study the morphology of the impact craters and the bulk composition of the residues left by soda-lime glass impactors. A more detailed structural and compositional study of impactor remnants was then performed using transmission electron microscopy (TEM), EDS, and electron diffraction methods. The TEM samples were prepared by focused ion beam (FIB) methods. This technique proved to be especially valuable in studying impact crater residues and impact crater morphology. Finally, we also showed that infrared microscopy (IR) can be a quick and reliable tool for such investigations. The combination of all of these tools enables a complete microscopic characterization of the craters. [source]


Fabrication of a novel micron scale Y-structure-based chiral metamaterial: Simulation and experimental analysis of its chiral and negative index properties in the terahertz and microwave regimes

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 6 2007
Nantakan Wongkasem
Abstract In this report, we describe the fabrication of a chiral metamaterial based on a periodic array of Y-shaped Al structures on a dielectric Mylar substrate. The unit cell dimensions of the Y-structure are ,100 ,m on a side with 8 ,m linewidths. The fabricated Y-structure elements are characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Quantitative elemental analyses were carried out on both the Y-structure, comprised of Al and its oxide, as well as adjacent regions of the underlying mylar substrate using the energy dispersive X-ray spectroscopy (EDS) capability of the SEM. Finite-Difference Time-Domain (FDTD) calculations of the negative index of refraction for a 3D wedge of multiple layers of the 2D metamaterials showed that these metamaterials possess double negative (,,,,,) electromagnetic bulk properties at THz frequencies. The same negative index of refraction was determined for a wedge comprised of appropriately scaled larger Y-structures simulated in the microwave region. This double negative property was confirmed experimentally by microwave measurements on a 3D wedge comprised of stacked and registered Y-structure sheets. Microsc. Res. Tech., 2007. © 2007 Wiley-Liss, Inc. [source]


TEM investigations of (In,Ga)N/GaN quantum structures

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008
P. Manolaki
Abstract The paper reports on the influence of the growth temperature on the structural and chemical properties of (In,Ga)N quantum wells (QWs) on GaN. Two different samples A and B were fabricated. The QWs of the sample A were grown at a constant temperature of 600 °C. For the QWs of the sample B the temperature was 530 °C, while for the GaN barrier it was raised to 600 °C. The chemical and structural properties were studied by electron diffraction contrast imaging using the 0001 and 0002 reflection, respectively. Sample A exhibits homogeneous (In,Ga)N QWs. For sample B some undulated strain contrast of the QWs is visible hinting to the formation of quantum dots (QDs). The self-organisation of (In,Ga)N QDs in sample B is also evidenced by composition sensitive STEM-HAADF imaging, where the individual (In,Ga)N layers exhibit inhomogeneous intensity as well as varied thickness. Moreover, energy dispersive X-ray spectroscopy yielded enrichment of indium at QD sites. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Growth and cathodoluminescent characteristics of blue emitting cerium-doped zinc aluminate layers synthesized by spray pyrolysis technique

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2004
M. García-Hipólito
Abstract Cerium doped ZnAl2O4 cathodoluminescent films have been deposited by ultrasonic spray pyrolysis deposition technique. X-ray diffraction measurements on these layers have shown that their crystalline structure depends on the substrate temperature. Cerium ions have been introduced into zinc aluminate films for produce violet-blue cathodoluminescence emissions. The behavior of cathodoluminescence emission intensity has been studied, as a function of the variations on doping concentrations, in the start spraying solution, substrate temperatures and the electron accelerating voltage. Concentration quenching of the cathodoluminescence occurs at about 0.8 percent of activator (Ce) concentrations inside the synthesized films. The surface morphology characteristics of these films, as a function of the substrate temperature, and the chemical composition, as measured by energy dispersive X-ray spectroscopy, are also exhibited. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Risk of silicosis in cohorts of Chinese tin and tungsten miners and pottery workers (II): Workplace-specific silica particle surface composition,,

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2005
J. Harrison
Abstract Background It is hypothesized that surface occlusion by alumino-silicate affects the toxic activity of silica particles in respirable dust. In conjunction with an epidemiological investigation of silicosis disease risk in Chinese tin and tungsten mine and pottery workplaces, we analyzed respirable silica dusts using a multiple-voltage scanning electron microscopy,energy dispersive X-ray spectroscopy (MVSEM-EDS). Methods Forty-seven samples of respirable sized dust were collected on filters from 13 worksites and were analyzed by MVSEM-EDS using high (20 keV) and low (5 keV) electron beam accelerating voltages. Changes in the silicon-to-aluminum X-ray line intensity ratio between the two voltages are compared particle-by-particle with the 90th percentile value of the same measurements for a ground glass homogeneous control sample. This provides an index that distinguishes a silica particle that is homogeneously aluminum-contaminated from a clay-coated silica particle. Results The average sample percentages of respirable-sized silica particles alumino-silicate occlusion were: 45% for potteries, 18% for tin mines, and 13% for tungsten mines. The difference between the pottery and the metal mine worksites accounted for one third of an overall chi-square statistic for differences in change in measured silicon fraction between the samples. Conclusion The companion epidemiological study found lower silicosis risk per unit cumulative respirable silica dust exposure for pottery workers compared to metal miners. Using these surface analysis results resolves differences in risk when exposure is normalized to cumulative respirable surface-available silica dust. Am. J. Ind. Med. 48:10,15, 2005. Published 2005 Wiley-Liss, Inc. [source]


Generation of paramagnetic hybrid inorganic/organic thin films

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2010
Abhinav Bhushan
Abstract There is a growing interest in developing advanced materials for thin film applications in biology, electronics, photonics and engineering. We report the development of hybrid inorganic/organic thin films containing nickel, iron and cobalt paramagnetic materials. By etching the resist in oxygen plasma after processing, most of the organic component of the resist was removed. The elemental chemical composition of the films was confirmed by energy dispersive X-ray spectroscopy. This process can potentially lead to patterning paramagnetic thin films containing paramagnetic materials by following standard photolithography protocols, obviating the need for a wet or vacuum metal deposition. Copyright © 2010 John Wiley & Sons, Ltd. [source]


Immersion Deposition of Pt Nanoparticles on Porous Silicon for Methanol Oxidation

CHINESE JOURNAL OF CHEMISTRY, Issue 9 2009
Xu Su
Abstract Porous silicon (PS) was chosen as the substrate for supporting the Pt particles because of great surface area, good conductivity and stability. Pt nanoparticles have been successfully prepared on the substrate by immersion deposition, which is convenient. The component and morphological properties of the films have been investigated by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), which shows that the Pt particles have small size and big specific surface. Cyclic voltammetry (CV) research showed that the Pt nanoparticles had novel catalytic activity for methanol when the immersion deposition time was past 24 min. [source]


Back-scattered electron imaging and elemental microanalysis of retrieved bone tissue following maxillary sinus floor augmentation with calcium sulphate

CLINICAL ORAL IMPLANTS RESEARCH, Issue 8 2008
Nicola Slater
Abstract Objectives: To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS). Material and methods: Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material. Results: Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio ,2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11,2.4) and C, mainly calcium phosphate (S/P,0.11; C), which had a mean Ca : P ratio of 1.63±0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process. Conclusions: CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone. [source]


Pyrotechnic Reaction Residue Particle Analysis

JOURNAL OF FORENSIC SCIENCES, Issue 2 2006
Kenneth L. Kosanke Ph.D.
ABSTRACT: Pyrotechnic reaction residue particle (PRRP) production, sampling and analysis are all very similar to that for primer gunshot residue. In both cases, the preferred method of analysis uses scanning electron microscopy to locate suspect particles and then uses energy dispersive x-ray spectroscopy to characterize the particle's constituent chemical elements. There are relatively few times when standard micro-analytical chemistry performed on pyrotechnic residues may not provide sufficient information for forensic investigators. However, on those occasions, PRRP analysis provides a greatly improved ability to discriminate between materials of pyrotechnic origin and other unrelated substances also present. The greater specificity of PRRP analysis is the result of its analyzing a large number of individual micron-sized particles, rather than producing only a single integrated result such as produced using standard micro-analytical chemistry. For example, PRRP analyses are used to demonstrate its ability to successfully (1) discriminate between pyrotechnic residues and unrelated background contamination, (2) identify that two different pyrotechnic compositions had previously been exploded within the same device, and (3) establish the chronology of an incident involving two separate and closely occurring explosions. [source]


Flame retardancy mechanisms of metal phosphinates and metal phosphinates in combination with melamine cyanurate in glass-fiber reinforced poly(1,4-butylene terephthalate): the influence of metal cation

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008
Ulrike Braun
Abstract The pyrolysis and fire behavior of glass-fiber reinforced poly(butylene terephthalate) (PBT/GF) with two different metal phosphinates as flame retardants in combination with and without melamine cyanurate (MC) were analyzed by means of thermogravimetry, thermogravimetry coupled with infrared spectroscopy, flammability, and cone calorimeter tests as well as scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence spectroscopy. In PBT/GF, dosages of 13,20% of the halogen-free flame retardant aluminum phosphinate or aluminum phosphinate in combination with MC fulfill the requirements for electrical engineering and electronics applications (UL 94,=,V-0; LOI,>,42%), whereas the use of the same amount of zinc phosphinate or zinc phosphinate in combination with MC does not improve the fire behavior satisfactorily (UL 94,=,HB; LOI,=,27,28%). The performance under forced flaming conditions (cone calorimeter) is quite similar for both of the metal phosphinates. The use of aluminum and zinc salts results in similar flame inhibition predominantly due to the release of the phosphinate compounds in the gas phase. Both metal phosphinates and MC interact with the polymer changing the decomposition characteristics. However, part of the zinc phosphinate vaporizes as a complete molecule. Because of the different decomposition behavior of the metal salts, only the aluminum phosphinate results in a small amount of thermally stable carbonaceous char. In particular, the aluminum phosphinate-terephthalate formed is more stable than the zinc phosphinate-terephthalate. The small amount of char has a crucial effect on the thermal properties and mechanical stability of the residue and thus the flammability. Copyright © 2008 John Wiley & Sons, Ltd. [source]