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Dioxide Particles (dioxide + particle)
Selected AbstractsHydrothermal Synthesis of Structure- and Shape-Controlled Manganese Oxide Octahedral Molecular Sieve NanomaterialsADVANCED FUNCTIONAL MATERIALS, Issue 9 2006W.-N. Li Abstract Highly uniform single-crystal Na-OMS-2 (OMS: octahedral molecular sieve), pyrolusite, and ,-MnO2 nanostructures with an interesting 3D urchinlike morphology have been successfully prepared using a hydrothermal method based on a mild and direct reaction between sodium dichromate and manganese sulfate. The crystal phases, shapes, and tunnel sizes of the manganese dioxide nanostructures can be tailored. Reaction temperature, concentrations of the reactants, and acidity of the solution play important roles in controlling the synthesis of these manganese dioxides. Field-emission scanning electron microscopy and transmission electron microscopy (TEM) studies show that the nanomaterials obtained are constructed of self-assembled nanorods. X-ray diffraction and TEM results indicate that the constituent manganese dioxide particles are single-crystalline materials. Energy dispersive X-ray analysis and magnetic studies imply that chromium cations may be incorporated into the framework and/or tunnels of the manganese dioxides. A mechanism for the growth of manganese dioxides with urchinlike architectures is proposed. [source] Optical and physicochemical properties of silica-supported TiO2 photocatalystsAICHE JOURNAL, Issue 8 2006Javier Marugán Abstract Commercial applications of photocatalysis in slurry reactors employing titanium dioxide particles present the disadvantage of the additional cost associated with the downstream catalyst separation. In past years a significant effort has been made to develop supported titania photocatalysts on particles of larger size in order to facilitate the sedimentation recovery process. In this work, two different silica materials have been used for preparing immobilized catalysts. Their physicochemical characteristics have been compared with those corresponding to two commercially available unsupported titanium dioxide catalysts. However, for reaction kinetics and reactor design purposes, three additional properties must be known: (i) the spectral specific radiation absorption coefficient, (ii) the spectral specific radiation scattering coefficient, and (iii) the asymmetry factor of a model for the angular distribution of the scattered photons (the phase function). They have been determined with specially designed spectrophotometer transmission, diffuse transmittance, and diffuse reflectance experiments and constitute the most significant addition to this contribution. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Controlling particle size during anatase precipitationAICHE JOURNAL, Issue 9 2001Sekhar Sathyamoorthy Titanium dioxide particles in the form of anatase are precipitated from concentrated titanyl sulfate solution in the sulfate process, which are then recovered by a filtration process downstream of the precipitation stage. A previous study by Sathyamoorthy et al. showed that the final anatase particles are aggregates (1-2 ,m) consisting of numerous crystals (7,8 nm) arranged in primary agglomerates (60,100 nm). Pigment quality is determined by crystal and primary agglomerate size. One way of improving filtration rate is by the formation of larger aggregates, while maintaining the crystal and primary agglomerate size at optimum values. In a new seeding procedure proposed, the controlled inoculation of seeds used in industry is combined with a new type of seed (Large Seeds). The new seeding procedure has the potential to increase downstream filtration efficiency by increasing aggregate size, while maintaining crystal and primary agglomerate sizes close to the values correctly obtained in industry. High yield in the precipitation process is also maintained. [source] Synthesis and characterization of nanocomposites of silicon dioxide and polyurethane and epoxy resin interpenetrating networkPOLYMER INTERNATIONAL, Issue 9 2003Hongwen Zhang Abstract Nanocomposites with varying concentrations of nanosized silicon dioxide particles were prepared by adding nanosilica to interpenetrating polymer networks (IPN)s of polyurethane and epoxy resin (PU/EP). The PU/EP IPNs and nanocomposites were studied by dynamic mechanical analysis, scanning electronic microscopy, wide-angle X-ray diffraction and small-angle X-ray scattering. The result showed that adding nanosize silicon dioxide can improve the properties of compatibility, damping and phase structure of IPN matrices. Copyright © 2003 Society of Chemical Industry [source] Serum biomarker profiling by solid-phase extraction with particle-embedded micro tips and matrix-assisted laser desorption/ionization mass spectrometry,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2008Arti Navare One of the main challenges in high-throughput serum profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is the development of proteome fractionation approaches that allow the acquisition of reproducible profiles with a maximum number of spectral features and minimum interferences from biological matrices. This study evaluates a new class of solid-phase extraction (SPE) pipette tips embedded with different chromatographic media for fractionation of model protein digests and serum samples. The materials embedded include strong anion exchange (SAX), weak cation exchange (WCX), C18, C8, C4, immobilized metal affinity chromatography (IMAC) and zirconium dioxide particles. Simple and rapid serum proteome profiling protocols based on these SPE micro tips are described and tested using a variety of MALDI matrices. We show that different types of particle-embedded SPE micro tips provide complementary information in terms of the spectral features detected for , -casein digests and control human serum samples. The effect of different sample pretreatments, such as serum dilution and ultrafiltration using molecular weight cut-off membranes, and the reproducibility observed for replicate experiments, are also evaluated. The results demonstrate the usefulness of these simple SPE tips combined with offline MALDI-TOF MS for obtaining information-rich serum profiles, resulting in a robust, versatile and reproducible open-source platform for serum biomarker discovery. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||