Espectrometria de massas com ionização por "electrospray" aplicada ao estudo de espécies inorgânicas e organometálicas

Although electrospray ionization mass spectrometry (ES-MS) has been extensively applied to study organic and biochemical species, it is also specially suitable to study inorganic and organo-metallic species. Such species, even those that are low-volatile or thermo-unstable, can be easily ionized or simply transferred from liquid to gas phase by electrospray. However, chemical transformations frequently occur during the process. This paper discusses the fundamental aspects of electrospray ionization as well as its analytical applicability to inorganic and organo-metallic species in order to spread the technique and make its characteristics more familiar to potential users.

Adsorção e dessorção aniônicas individuais por gibbsita pedogenética

Anion adsorption/desorption dynamics was studied as individual processes on surface of particles of a gibbsitic clay. The data suggest a remarkable gibbsite role as nitrate leaching retardant in soil. The opposite behavior of gibbsite towards adsorption/desorption of silicate and phosphate suggests the need of an adequate compromise solution regarding interval and rate applications of anions in cultivated gibbsitic soils. The high P adsorption verified in pH values lower than that reported for the point of zero charge of synthetic Al-hydroxides implies that this process takes place in pedogenic gibbsites through inner sphere complexation.

Processos físico-químicos em drenagem ácida de mina em mineração de carvão no sul do Brasil

Acid mine drainage generated from coal mine showed a pH of 3.2, high concentrations of SO4(2-), Al, Fe, Mn, Zn and minor As, Cd, Co, Cr, Cu, Ni and Pb. The major reduction in the concentration occurred for Al, As, Cr, Fe and Pb after the treatment with CaO. The evolution of these acid waters within the tributary stream showed decreasing concentration for all soluble constituents, except Al. This natural attenuation was controlled by pH (6.4 to 10.8) as a result of concurrent mixing with tributary stream and reaction with local bedrock that contains limestone. Aluminum increasing concentration during this evolution seems to be related to an input of Al-enriched waters due to the leaching of silicate minerals in alkaline conditions.

Uso das técnicas de infravermelho e de ressonância magnética nuclear na caracterização da reação ácido-base de um cimento odontológico experimental

Glass ionomer cements (GICs) are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid) in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental and to investigate the structural changes during hardening of the cements by FTIR and Al MAS NMR. These analyses showed that the experimental glass powder reacted with organic acid to form the GICs and it is a promising material to manufacture dental cements.

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1902/04/30 (A5,N52).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1904/02/29 (A7,N1).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1902/09/30 (A5,N56)- (A5,N57).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1898/03 (A1,N3).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1901/07/31 (A4,N43).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1903/10/31 (A6,N70).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1905/05 (A8,N5).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1901/03 (A4,N39).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1899/11 (A2,N23).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1905/10 (A8,N9).

L'Espérantiste : organe propagateur de la langue internationale "Espéranto" paraissant à la fin de chaque mois / directeur-fondateur : L. de Beaufront

1900/10 (A3,N34).