RESUMO
Cobalt supported on mesostructured TiO2 catalysts has been prepared by a wet-impregnation method. The Co/TiO2 catalytic system showed better catalytic performance after support calcination at 380 °C. Co nanoparticles appeared well distributed along the mesopore channels of TiO2. After reduction pretreatment and reaction, a drastic structural change leads to mesopore structure collapse and the dispersion of the Co nanoparticles on the external surface. Along this complex process, Co species first form discrete nanoparticles inside the pore and then diffuse out as the pore collapses. Through this confinement, a strong metal-support interaction effect is hindered, and highly stable metal active sites lead to better performance for Fischer-Tropsch synthesis reaction toward C5+ products.
RESUMO
Using dual mesoporous titania as a support, due to the presence of intrinsic Brönsted acid sites, the main approach to 4,6-dimethylbenzothiophene (46DMDBT) hydrodesulfurization (HDS) becomes the direct desulfurization (DDS) route through isomerization and dismutation reactions, instead of the hydrogenation (HYD) pathway usually observed with a conventional promoted (by Ni or Co) MoS2/Al2O3 catalyst.
RESUMO
Two hundred and seventy-seven multidrug resistant clinical isolates [K. pneumoniae, (N = 87); E coli, (N = 30); Salmonella typhimurium (N = 100); P. aeruginosa, (N = 30); S. aureus, (N = 30)] from hospitalized patients specimens, were tested in vitro for sensitivity to Ciprofloxacin. Application of the disk diffusion test and determination of the minimal inhibitory concentration by the microdilution method indicated that, almost all isolates were sensitive to the drug. Overall, S. aureus and P. aeruginosa were the less sensitive organisms. Ciprofloxacin-resistant mutants occurred at frequencies of > or = 10(-5)/CFU.
Assuntos
Ciprofloxacina/farmacologia , Infecções por Enterobacteriaceae/microbiologia , Enterobacteriaceae/efeitos dos fármacos , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Brasil , Resistência Microbiana a Medicamentos/genética , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/isolamento & purificação , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/isolamento & purificação , Infecções por Salmonella/microbiologia , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Salmonella typhimurium/isolamento & purificação , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificaçãoRESUMO
The synthesis of the dodecapeptide [sequence (20--31)] representing the hypothetical calcium binding site I of calmodulin by classical methods in solution is described. The interaction of this synthetic calmodulin fragment with calcium ions has been investigated by CD in water and in 98% trifluoroethanol solution. Calcium ions have no effect on the dichroic absorption of the dodecapeptide in aqueous solution in the wavelength range 200-250 nm. However, in 98% trifluoroethanol a linear variation of the CD properties has been observed as a function of the Ca2/peptide molar ratio. The CD results indicate the formation of a 1 : 1 calcium-dodecapeptide complex with a very high binding constant.