LC-MS characterization of intermediates and products of acid orange dyes after laccase treatment

Poster apresentado em COST 847 & D32 actions joint meeting, na Povoa de Varzim, 200

Enzymatic degradation of azo dyes under long time oxidative conditions

Trametes villosa laccase was used for direct azo dye degradation for which the reaction products were analyzed over long periods of time. Laccases have been extensively studied for the degradation of azo dyes [1-3].These enzymes are multicopper phenol oxidases that decolorize azo dyes through a highly non-specific free radical mechanism forming phenolic type compounds, thereby avoiding the formation of toxic aromatic amines [4,5].In the literature, there are a large number of papers reporting on decolorization of azo dyes however the fate of the products of azo dye laccase reactions is ignored [6-8]. Therefore, the purpose of this work is the study of the azo dye degradation products in the presence of laccase. Direct azo dye laccase degradation and amino-phenols polymerization was performed for several days. The formed soluble products were studied by LC-MS while the polymerized insoluble products were studied by 13C -NMR. LC-MS analysis shows the formation of phenolic compounds in the dye oxidation process as well as a large amount of polymerized products that retain the azo group integrity. The amino-phenols reactions were also investigated by 13C-NMR and LC-MS analysis and the real polymerization character of laccase enzymes was shown. This study highlights the fact that laccases polymerize the reaction products obtained in long time batch decolorization processes of the azo dyes. These polymerized products provide unacceptable color levels in effluents limiting the application of laccases as bioremediation agents

Eye Size at Birth in Prosimian Primates: Life History Correlates and Growth Patterns

BACKGROUND: Primates have large eyes relative to head size, which profoundly influence the ontogenetic emergence of facial form. However, growth of the primate eye is only understood in a narrow taxonomic perspective, with information biased toward anthropoids.\ud \ud METHODOLOGY/PRINCIPAL FINDINGS: We measured eye and bony orbit size in perinatal prosimian primates (17 strepsirrhine taxa and Tarsius syrichta) to infer the extent of prenatal as compared to postnatal eye growth. In addition, multiple linear regression was used to detect relationships of relative eye and orbit diameter to life history variables. ANOVA was used to determine if eye size differed according to activity pattern. In most of the species, eye diameter at birth measures more than half of that for adults. Two exceptions include Nycticebus and Tarsius, in which more than half of eye diameter growth occurs postnatally. Ratios of neonate/adult eye and orbit diameters indicate prenatal growth of the eye is actually more rapid than that of the orbit. For example, mean neonatal transverse eye diameter is 57.5% of the adult value (excluding Nycticebus and Tarsius), compared to 50.8% for orbital diameter. If Nycticebus is excluded, relative gestation age has a significant positive correlation with relative eye diameter in strepsirrhines, explaining 59% of the variance in relative transverse eye diameter. No significant differences were found among species with different activity patterns.\ud \ud CONCLUSIONS/SIGNIFICANCE: The primate developmental strategy of relatively long gestations is probably tied to an extended period of neural development, and this principle appears to apply to eye growth as well. Our findings indicate that growth rates of the eye and bony orbit are disassociated, with eyes growing faster prenatally, and the growth rate of the bony orbit exceeding that of the eyes after birth. Some well-documented patterns of orbital morphology in adult primates, such as the enlarged orbits of nocturnal species, mainly emerge during postnatal development.\ud \u

Entwicklung eines Verfahrens zur Aufbereitung von Abwaessern aus der Textilindustrie mit dem Schwerpunkt des Abbaus von Azofarbstoffen in einem zweistufigen Bio-Membran-Reaktor (BMR) Schlussbericht

SIGLEAvailable from TIB Hannover: F04B1489 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman

Photochemistry of Transition Metal Complexes Induced by Outer-Sphere Charge Transfer Excitation

The intermolecular (outer sphere, OS) interaction of a reducing and an oxidizing metal complex generates a new optical transition involving charge transfer (CT) from the electron donor to the acceptor. OS CT transitions are classified according to the redox site (metal or ligand). Generally, the interaction between donor and acceptor is facilitated by ion pairs consisting of an oxidizing complex cation and a reducing complex anion. There are also ion pairs which are composed of a metal complex and an organic counter ion as electron donor or acceptor. In addition, the review includes examples of OS CT interaction which do not involve ion pairs at all. — A short introduction into the theory is followed by the discussion of the spectroscopy of OS CT of transition metal complexes. Finally, photoreactions induced by OS CT transitions are reviewed. The optical transfer is frequently followed by a rapid back electron transfer which regenerates the starting complexes. In many cases the primary products are kinetically labile and substitution reactions compete successfully with back electron transfer. As a result stable redox products may be formed. As an alternative, the substitution can be followed by back electron transfer. Product formation appears then as a substitution of the starting complexes. The various possibilities are illustrated by appropriate examples