INCORPORAÇÃO DE NB EM ZEÓLITAS: USO COMO CATALISADORES NA DECOMPOSIÇÃO DO PERÓXIDO DE OXIGÊNIO

In this work, the comercial zeolites ZSM-5 and Y were submitted to previous ionic change with NH4NO3, followed by the addition of Nb. The incorporation of Nb on its structure aims increasing the acidity and improved the catalyst activity of these zeolites. The materials obtained are characterized by X-Ray diffraction patterns, chemical analysis, SEM and textural analysis by N2 adsorption. Furthermore, the materials were avaliated by decomposition reaction of the H2O2. The Nb presence improved the catalytic activity for H2O2 decomposition. Moreover, high amounts of Nb incorporated into zeolites caused a partial destruction of the structure of the materials as evidenced by X-Ray diffraction patterns.

CARACTERIZACION ECOLOGICA DE LA SALINA ARTIFICIAL POZOS COLORADOS, CARIBE COLOMBIANO

An ecological study of Pozos Colorados marine brine was carried out between January an August 1987. Although the two sampled stations were greatly different to each other in genera the dynamics of the ecosystem were apparently controlled by salinity, which varied between 7 and 341 °/oo; its increase, accompanied by a decrease of the water level, possibly generated temperature increament and a decrease of the dissolved oxygen, ranging between 26,3 an 41 °C for the first and between 0 and 5,4 mg/l for the latter. Although the average pH wa neutral (7,5), this reductive environment, also characterized by the abundance of organi matter, ocassionaily generated a slight acidity (6,7). The net primary production was negative i most cases, as a result of an intense respiratory activity. Therefore, the system behaved a heterotrophic, using organic matter as subsidiary energy. The species dynamics was possibl determined by rain and ionic change relations, showing a succesion dominated initially b benthic cyanophites and Dunaliella viridis; an increase in salinity was followed by the appear ance of Dunaliella salina, which dominated in high salinities, before the total dominance of red and pink bacteria began.

Influence of ions and dinitrophenol on adrenocortical steroidogenesis

The Na, K, Ca, Mg or PO4 content of an artificial medium, shown to support steroidogenesis as well as homologous blood, was altered individually, and the influence of each ionic change on the biosynthetic function of the perfused calf adrenal investigated under three conditions: a) without ACTH, b) with ACTH and c) with steroid substrates. The effect of dinitrophenol (DNP) was explored under similar conditions. Both ACTH-stimulated and unstimulated glands perfused without Ca exhibited an appreciable decrement in corticoid output without any depletion in metabolic activity. Omission of Mg, K or PO4 ions, and reduction of the Na content from 149 to 125 mEq/l. exerted no significant effect. None of the ionic alterations modified the specific, enzymatic hydroxylation or 3ß-dehydrogenase activities of adrenals perfused with various steroid substrates. Adrenals perfused with a markedly elevated K level (25.0 rather than 3.4 mEq/l.) were not inhibited but instead autonomously responded to it by secreting increased amounts of corticoids. Addition of 10–4 M DNP, with and without ACTH, resulted in a striking suppression of corticoid production without a commensurate metabolic depression, and induced depletions of from 80 to 100% in the ability of exposed glands to perform 11ß-, 17α- and 21-hydroxylation without affecting their transformation of the Δ5-3ß-OH group to Δ4-3-ketone.

NOTE ON THE USE OF NON-ORTHOGONAL WAVE FUNCTIONS IN PERTURBATION CALCULATIONS

A method of first approximation is proposed for handling collision problems involving a chemical or ionic change, so that the interaction energy function is different at the beginning and end of the collision.