Propriedades estruturais de géis de sílica preparados com adições de dodecil sulfato de sódio

This work aims to study the structural characteristics of silica gels obtained from the acid hydrolysis of tetraethoxysilane (TEOS) in water solutions with different concentrations of sodium dodecyl sulfate (SDS). The structural characteristics were studied in stages ranging from the wet gel to the dry stages of the gels (aerogels and xerogels). Aerogels were obtained by ambient pressure drying (APD) after silylation process using trimethylchlorosilane (TMCS) as silylating agent. Xerogels were obtained by conventional evaporating the liquid phase from non silylated gels. The samples were characterized by nitrogen adsorption and small angle X-ray scattering (SAXS). The structure of the wet gels and of the aerogels prepared with the surfactant exhibited characteristics of mass-fractal structures with fractal dimension D in the range 2.1-2.2 for the wet gels and 2.3-2.4 for the aerogels. The characteristic size  of the fractal domain reduces while the size a0 of the primary silica particle composing the fractal structure increases with the drying of the gels, in a process in which share of the porosity is eliminated. Aerogels exhibited typical values for the specific surface of 900 m2g-1 and of 3.5 cm3.g-1 for the total pore volume. These values are correspondingly comparable to those of the aerogels prepared by supercritical drying, since the silylation process replaces hydrophilic –OH groups by hydrophobic –Si-R3 ones, inhibiting the porosity elimination on drying. The silica particle size also increases lightly with the silylation because the attachment of the –Si-R3 groups on the silica surface. The pore size distribution curves of the aerogels are similar for all samples exhibiting a maximum in around 40 nm, independent the concentration of surfactant. This suggests that the characteristic size of 40 nm is due to the association of surfactant micelles... (Complete abstract click electronic access below)

Effectof inoculum in the emulsification index of biossufactants produced by Bacillus velezensis using wheat bran as substrate in solid-state fermentation

Conselho Nacional de Desenvolvimento em Pesquisa (CNPq)

Estudo sobre desruptores endócrinos em sistemas aquáticos: detecção e perspectivas de tratamento das águas do Rio Aporé-MS/GO, utilizando-se adsorventes sólidos

Pós-graduação em Ciência dos Materiais - FEIS

Efeito do ambiente alterado no epitélio da escama, nas brânquias e na alimentação de Prochilodus lineatus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cerâmicas porosas a base de zircônia na forma de filmes suportados preparados a partir de emulsões

Pós-graduação em Química - IQ

Catalisadores de cobre suportados em óxidos de zircônio hierarquicamente estruturados para a reação de desidrogenação de etanol

Pós-graduação em Química - IQ

Controle da porosidade e das características ácido-base de óxidos mistos derivados da hidrotalcita para aplicação em catálise

Pós-graduação em Química - IQ

Síntese de nanopartículas de sulfeto de cobre, preparação e estabilidade coloidal de fluidos trocadores de calor em meio aquoso

Pós-graduação em Química - IQ

Desenvolvimento de revestimentos siloxano-PMMA reforçados por nanotubos de carbono, óxido de grafite e óxido de grafite reduzido para aplicações anticorrosivas

Pós-graduação em Química - IQ

Estudo microbiológico comparativo entre sabão de clorexidina 2% e um novo sabão antisséptico para lavagem pré-operatória das mãos

Objective: To evaluate, by means of a microbiologic study, two kinds of soaps suggested by surgeons for presurgical handwashing, comparing a well-known antibacterial soap with a new soap formulated from vegetable oils. Materials and methods: Ten volunteers performed handwashing according to previously established protocols for routine antisepsis in operating rooms using 3 different soaps: a common, commercially marketed soap, serving as the control group (Group 1), with no antibacterial characteristics; a soap with 2% chlorhexidine (Group II); and a new soap formulated from vegetable oils at a concentration of 20%, known as surfactant, which was designed by the Chemistry Institute (Unesp/Araraquara – Grupo de Materiais Fotônicos) (Group III). The microbiological samples were collected immediately before and after handwashing and one hour later with the volunteer wearing surgical gloves. Results: ANOVA revealed that the following significant differences are found in the number of bacterial colonies: between soap types (a smaller number of colonies in the Group II soap), between periods (reduction in the number of colonies in the Group II soap), and the significant effect of the soap versus time interaction. Conclusion: The 2% chlorhexidine soap performed better in reducing the number of bacterial colonies on the hands immediately after handwashing and after one hour with the use of surgical gloves, when compared to the 20% surfactant soap.

Desenvolvimento, caracterização e ação anti-biofilme oralde sistemas nanoestruturados bioadesivos contendo o peptídeo KSL-W

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo de interação entre um hormônio estrógeno e modelos simples de membrana biológica

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Utilização de melaço, manipueira e soro de queijo como substratos para produção de biossurfactante por Bacillus Pumilus e sua aplicação em biorremediação de solo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da maturidade pulmonar de cordeiros nascidos a termo e prematuros pela análise citológica, Test de Clements e contagem de corpos lamelares do líquido amniótico

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mass and surface fractal in supercritical dried silica aerogels prepared with additions of sodium dodecyl sulfate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)