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Understanding the mechanism of aluminium nanoparticle oxidation
Rai, A.,Park, K.,Zhou, L.,Zachariah, M. R. INSTITUTE OF PHYSICS 2006 COMBUSTION THEORY AND MODELLING Vol.10 No.5
<P> Aluminium nanoparticles have gained importance in the last decade because of their increased reactivity as compared with traditional micron-sized particle. The physics of burning of aluminium nanoparticle is expected to be different than that of micron-sized particles, and the current article is motivated by these differences. We have previously measured the size resolved reactivity of nanoaluminium by single-particle mass spectrometry, to which we now add transmission electron microscope (TEM) and an on-line density measurement. The latter two studies revealed the presence of hollow particles following oxidation of nanoaluminium and indicating the significance of diffusion of aluminium in the overall process. Based on experimental evidence, we believe that aluminium nanoparticle oxidation occurs in two regimes. Prior to melting of aluminium slow oxidation occurs through the diffusion of oxygen through the aluminium oxide shell. Above the melting point, we transition to a fast oxidation regime whereby both aluminium and oxygen diffuse through the oxide shell to enhance the oxidation rate. We also develop a phenomenological model for nanoaluminium oxidation that accounts for the experimentally observed rates, the fact that both fuel and oxidizer are diffusing, and a new effect related to internal pressure gradients. The latter phenomen is based on molecular dynamic simulations suggesting that there are large pressure gradients present inside these particles, with the aluminium core under a positive pressure and the aluminium oxide shell under a negative pressure. We have considered the effect of these pressure gradients on the oxidation process. A power law relation was obtained (t ∝ r1.6± 0.1) between the time required for oxidation and particle radius.</P>
Burkholderia cepacia Complex Infection in a Cohort of Italian Patients with Cystic Fibrosis
Lambiase, Antonietta,Raia, Valeria,Stefani, Stefania,Sepe, Angela,Ferri, Pasqualina,Buonpensiero, Paolo,Rossano, Fabio,Pezzo, Mariassunta Del The Microbiological Society of Korea 2007 The journal of microbiology Vol.45 No.3
The aims of this study were to detect Burkholderia cepacia complex (Bcc) strains in a cohort of Cystic Fibrosis patients (n=276) and to characterize Bcc isolates by molecular techniques. The results showed that 11.23% of patients were infected by Bcc. Burkholderia cenocepacia lineage III-A was the most prevalent species (64.3%) and, of these, 10% was cblA positive and 50% esmR positive. Less than half of the strains were sensitive to ceftazidime, meropenem, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole. About half of the strains (41%) had homogeneous profiles, suggesting cross-transmission. The infection by B. cenocepacia was associated to a high rate of mortality (p=0.01).
Burkholderia cepacia Complex Infection in a Cohort of Italian Patients with Cystic Fibrosis
Antonietta Lambiase,Valeria Raia,Stefania Stefani,Angela Sepe,Pasqualina Ferri,Paolo Buonpensiero,Fabio Rossano,Mariassunta Del Pezzo 한국미생물학회 2007 The journal of microbiology Vol.45 No.3
The aims of this study were to detect Burkholderia cepacia complex (Bcc) strains in a cohort of Cystic Fibrosis patients (n=276) and to characterize Bcc isolates by molecular techniques. The results showed that 11.23% of patients were infected by Bcc. Burkholderia cenocepacia lineage III-A was the most prevalent species (64.3%) and, of these, 10% was cblA positive and 50% esmR positive. Less than half of the strains were sensitive to ceftazidime, meropenem, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole. About half of the strains (41%) had homogeneous profiles, suggesting cross-transmission. The infection by B. cenocepacia was associated to a high rate of mortality (p=0.01).