Papers by Keyword: Nanosized Particle

Abstract: Nowadays, the application of nano-sized anatase titanium dioxide particles becomes one of the essential research focuses by many experts, especially for biomedical applications. In this work, we report the utilization of coprecipitation route in preparing nano-sized anatase titanium dioxide as an antifungal agent. The data analysis for the XRD data of the titanium dioxide particles showed that the sample crystallized with anatase structure and sized in the nanometric size of 13.30 nm. The particle size obtained from Scherrer’s analysis of the XRD data was quite similar to the particle size obtained from electron microscopy investigation. Furthermore, the small-angle scattering data presented that the anatase titanium dioxide constructed a 3-dimensional structure with a compact structure originating from the fractal dimension value of approximately 3. The functional groups of the nano-sized anatase titanium dioxide were traced in the wavelength range of 500-1500 cm^-1 showing the presence of Ti-O bonding. Interestingly, the prepared sample in this experiment exhibited an excellent performance as an antifungal agent represented by inhibition zone diameter of 3.59 mm.

Abstract: The focus of this study is to investigate the effect of carboxylated styrene-butadiene rubber (SBR) latex on the dynamic rheologcial properties of paper coating suspensions modified with nanosized particles. The elastic storage modulus G′ and the viscid loss modulus G′′ are used to evaluate the dynamic rheologcial properties of paper coating suspensions. The effects of different amount carboxylated styrene-butadiene rubber latex on the flow parameters of paper coating suspensions are comparatively presented. It is shown that the dynamic elastic storage modulus G′ and viscid loss modules G′′ of paper coating suspensions increase with the SBR content change from 13% to 18%. The dynamic rheologcial properties are related to the strength of the network structure of paper coating suspensions. It is also found that the elastic storage modulus G′ of paper coating suspensions is larger than viscid loss modulus G′′, which indicates that paper coating suspensions in this investigation all behave like a viscoelastic solid.

Abstract: The effect of calcination (1000-1400 oC) and sintering temperatures (1400-1600 oC) on the phase formation and microstructure of barium strontium zirconate titanate [(Ba0.25Sr0.75)(Zr0.75Ti0.25)O3; BSZT] ceramics were investigated. BSZT powders were prepared by the solid-state reaction method. Higher calcination temperatures increased the percentage of the perovskite phase, but decreased the lattice parameter a of BSZT powders. The pure perovskite phase of BSZT powders was detected above the calcination temperature of 1350 oC. The microstructure of BSZT powders exhibited an almost-spherical morphology and had a porous agglomerated form. The average particle size and the average grain size of the ceramics were increased with the increase of calcination and sintering temperatures. The highest density of the samples was 5.42 g/cm3 which was obtained from ceramic sintered at 1550 oC for 2 h.

Abstract: Perovskite SrZrO3 ceramics were successfully prepared via a combustion technique. The effect of calcination temperatures (900-1400oC) and sintering temperatures (1400-1650oC) on phase and morphology evolution of perovskite SrZrO3 ceramics were studied. The highest purity of perovskite phase powder was obtained at 1250 oC and the purity of the perovskite phase of SrZrO3 ceramics were detected in the samples sintered at 1550 oC for 6 h. The SEM results showed the average particle size (84-214 nm) and the average grain size (0.35-2.09 µm) of samples increased with the increase of firing temperatures. The shrinkage of the ceramics increased as the sintering temperatures increased. The maximum density was ~98.4% of the theoretical density for the sample sintered at 1550 oC for 6 h.

Abstract: This work has as objective the synthesis for the method by combustion reaction of catalytic supports of α-Al2O3 modified with ZnO and Fe2O3 with and without impregnation of the species it activates (Ni) and your structural and morphologic characterization. The catalytic supports were obtained by method of the synthesis da combustion reaction. The catalytic supports were characterized by XRD, adsorption of nitrogen by BET method and infrared. The results of XRD showed the formation of powders with high cristalinity, characteristic picks of difraction of the phase α-Al2O3 indicating that there was the partial substitution of the ions of Al3+ for Zn2+ and Fe3+ in the hexagonal net of the alumina. The impregnation of the nickel promoted an increasing in the size of the particles, this carried to reduction of the superficial area of the same, of the volume and of the diameter of the pores of the structure of the material. Were accomplished catalytics tests in row of seats scale. The result of catalytic tests showed that the developed catalysts in this work were efficient in the methane conversion process.

Abstract: Friction stir processing (FSP) has been applied to fabricate 10~20 vol% nano-sized ZrO2 and 5~10 vol% nano-sized SiO2 particles into an Mg-AZ31 alloy to form bulk composites under the FSP parameters of advancing speed of 800 rpm and pin rotation of 45 min/min. The microstructures and mechanical properties of the resulting composites were investigated. The clustering size of nano-ZrO2 and nano-SiO2 particles, measuring average ~200 nm was relatively uniformly dispersed, and the average grain size of the both Mg alloy of the composites varied within 1.0~2.0 μm after four FSP passes. No evident interfacial product between ZrO2 particles and Mg matrix was found during the FSP mixing in AZ31-Mg/ZrO2. However, significant chemical reactions at the AZ31-Mg/SiO2 interface occurred to form the Mg2Si phase. The mechanical responses of the nano-composites in terms of hardness and tensile properties are examined and compared.

Abstract: The spherical nano-sized bioactive particles in the system of CaO-P2O5-SiO2 were bio-mimetically synthesized using micro-emulsion method. The microstructures and properties of the bio- mimetic nano-materials were characterized using XRD, FTIR, SEM/EDAX and TEM techniques. It was indicated that the nano-particles possessed glassy structural characteristics. The porous composite for bone tissue reconstruction was prepared by compounding poly (hydroxybutyrate-2-co-2-hydroxyvalerate) (PHBV) and the nano-particles of bio-mimetic bioactive glasses (BMBG). Bone-like hydroxyl- carbonate-apatite (HCA) could formed on the surface of porous composite by immersing the composite in simulated body fluid (SBF) at 37°C for 8 hours. With increase of immersion time, the morphology of HCA changed from spherical into flake-like crystals. The study on cells attachment of the porous PHBV/BMBG composite proved that the material possessed satisfactory bioactivity, bio-mineralization function and cells biocompatibility.

Abstract: In this work, nano-sized strontium containing tricalcium phosphate (SrTCP) particles with different strontium content were prepared using co-precipitation method in an ice-water bath and then 800°C calcination. The AAS results show that the relative Sr/(Sr+Ca) ratios are consistent with the amount of strontium added in the initial solution but larger than the designed molar percentage. The TEM micrographs demonstrate the size of the SrTCP particles is in the region of 150-400 nm while the pure TCP particle is about 500nm. The SEM photographs show the morphology of the particles before and after incorporation of strontium and it is obvious that the particle size of SrTCP decrease with the increasing of strontium content.

Abstract: Nanosize particle flow is significantly affected by inter-particle force. Due to the inter-particle force, the most significant characteristic of nanosize particle flow may become the formation of agglomerates or clusters which considerably affects the flow patterns. The formation of agglomerates or clusters results in a reduction in the number and an increase in the size of particles, both of which directly affect the frequency of inter-particle collisions and, in turn, the particle phase properties such as viscosity and pressure, as well as gas/particle drag force in gas/particle flow systems. In this present work, we focus our attention on the verification of nanosize particle flow behavior due to the formation of agglomerates or clusters under different fluctuation of flow and inelasticity of particle collision. By extending the application of the cohesive model using kinetic theory to nanosize particle flow system, we performed the homogeneous simple shear flow analysis using various fluctuation energy and restitution coefficient. The predicted flow properties, such as particle diameter growth, agreed well with the expected trends.