XRD Techniques (xrd + techniques)

Distribution by Scientific Domains

Selected Abstracts

Pilot-scale combustion of fast-pyrolysis bio-oil: Ash deposition and gaseous emissions

Ala Khodier
Abstract Fast pyrolysis is a promising method to transform solid biomass into a liquid product called "bio-oil" with an energy density of four to five times greater than the feedstock. The process involves rapidly heating biomass to 450,600°C in the absence of air and condensing the vapor produced to give bio-oil. Typically, 50,75% (weight) of the feedstock is converted into bio-oil that has a number of uses, for example energy production or bio-refinery feedstock. This study investigated the gaseous emissions and ash deposition characteristics resulting from bio-oil combustion in a pilot scale combustion test rig at Cranfield University. A feeding system with heated lines and heated/stirred reservoir was used to feed a spray nozzle in the combustion chamber. Ash deposit samples were collected from the resulting flue gas using three air-cooled probes that simulate heat exchanger tubes with surface temperatures of 500, 600, and 700°C. The deposits formed were analyzed using SEM/EDX and XRD techniques to assess the corrosion potential of the deposits. The results are compared to measured ash deposit compositions formed from biomass combustion. Thermodynamic modeling software was used to make predictions for the partitioning of a range of elements for bio-oil combustion and the results compared to the measured data. © 2009 American Institute of Chemical Engineers Environ Prog, 2009 [source]

Biomorphic Silicon Carbide Coated with an Electrodeposition of Nanostructured Hydroxyapatite/Collagen as Biomimetic Bone Filler and Scaffold,

M. Lelli
Abstract The paper describes the method of preparation and chemical/physical characterization of a new biomaterial to be used as a bone substitute and bone-tissue engineering scaffold, which synergistically joins a porous bio-inspired morphology and the mechanical properties of biomorphic silicon carbide (BioSiC) with the surface bioactivity of a nanostructured hydroxyapatite/collagen biomimetic coating. FT-IR spectroscopy and XRD techniques are utilized to determine the chemical coating's composition. The morphology and size of the inorganic and protein components are investigated by TEM. The characteristic morphology of BioSiC channels and pores, which differ as a function of the transversal or longitudinal cross-section and with etching time, are investigated by SEM. Natural wood transformed into BioSiC acts as a cathode in an electrochemically assisted process that produces on its surface a biomimetic coating of hydroxyapatite nanocrystals and reconstituted type I collagen fibrils, producing an innovative apatite/collagen biomimetic porous bone filler and scaffold for tissue engineering. [source]

FMR study of ultrahigh vacuum e-beam evaporated Co23Cu77 nanogranular films: Magnetotransport properties

R. Mustafa Öksüzoglu
Abstract The magnetic, magnetotransport and structural properties of Co23Cu77 granular thin films (7,43 nm) have been investigated using ferromagnetic resonance (FMR) and high-resolution XRD techniques. Co particles possess a crystalline fcc structure in the investigated films. A correlation between the GMR effect and the anisotropy field has been found, which increases with increasing film thickness. Temperature-dependent FMR measurements revealed a blocking effect, which results from the competition of long range dipole,dipole interaction and anisotropy fields of Co particles. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

New route to synthesis of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross-coupling reactions

Feyyaz Durap
Abstract Herein we report a new method for the synthesis and characterization of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP-stabilized palladium(0) nanoclusters with a particle size of 4.5 ± 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 °C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV,vis, and XRD techniques. The PVP-stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP-stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Study on Lead Dioxide Modified Electrode and Its Application in Detection of Phenols

Ai Shi-Yun
Abstract The conditions for the preparation of PbO2 modified Pt rotation disc electrode in solutions containing HC104 and Pb(II) were studied, and the morphology and composition of the obtained PbO2 film were characterized by SEM and XRD techniques, respectively. The results show that the modification process of PbO is dependent on the rotation velocity of the electrode and the concentrations of HCIO4 and Pb(II). And it was observed that the obtained PbO2 film was rutile ,-PDO2 structure. At a certain positive potential, HO· and HO2· radicals can be generated on the surface of the modified PbO2/Pt electrode and then oxidize phenols. According to the change of the responding anodic current, the determination of phenols was realizable and good results were obtained. [source]