Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Genus. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Current advances and applications of in-tube solid-phase microextraction

Abstract: In-tube solid-phase microextraction (in-tube SPME) with capillary column as extraction device allows direct coupling to high performance liquid chromatography (HPLC) systems. This technique associates the advantages of on-line systems with the advantages of miniaturized systems. Since its development, in-tube SPME has been continuously improved. New couplings have also been evaluated on the basis of state-of-the-art HPLC instruments. Major achievements include the development of new capillary coatings to enhance the in-tube SPME performance (sorption capacity and selectivity). Innovative SPME fibers (fiber in-tube SPME) and capillary coatings based mainly on monolithic, nanoparticles, ionic liquids, carbon, and hybrid materials have been evaluated. This review provides an overview of the fundamental theory and current advances concerning in-tube SPME systems and highlights their main applications in environmental, clinical, and food analyses.

Anion exchange in layered double hydroxides by surfactant salt formation

Abstract: In this paper a method of anion exchange in layered double hydroxides (LDHs) based on the formation of a salt between an anionic and a cationic surfactant, which is extracted from aqueous solution into an organic unmixed phase, is discussed. Two Zn(II)–Cr(III) LDHs, synthesised by direct coprecipitation under constant pH intercalated with dodecylsulfate (DS) and dodecylbenzenesulfonate (DBS), were used as starting materials (precursors). By this method various inorganic and organic anions can be intercalated by exchange with the surfactant anion in the interlamellar domain, resulting in new intercalated materials. The kinetics of such exchange and the possibility of controlled partial exchange are also discussed. The exchanged materials obtained showed phase purity and considerable high crystallinity. Another advantage of this method is related to the conditions in which the precursor and the final products can be obtained, i.e. the precursors are very easy to synthesise and no further treatments for use in this exchange, such as hydrothermal treatment, are required in either case. Moreover, the kinetic study showed that the anion exchange is very quick. An advance on anion exchange process in LDHs is also demonstrated by the possibility of controlled quantitative substitution.

Repeated evolution of soldier sub-castes suggests parasitism drives social complexity in stingless bees

Abstract: The differentiation of workers into morphological castes represents an important evolutionary innovation that is thought to improve division of labor in insect societies. Given the potential benefits of task-related worker differentiation, it is puzzling that physical worker castes, such as soldiers, are extremely rare in social bees and absent in wasps. Following the recent discovery of soldiers in a stingless bee, we studied the occurrence of worker differentiation in 28 stingless bee species from Brazil and found that several species have specialized soldiers for colony defence. Our results reveal that worker differentiation evolved repeatedly during the last ~ 25 million years and coincided with the emergence of parasitic robber bees, a major threat to many stingless bee species. Furthermore, our data suggest that these robbers are a driving force behind the evolution of worker differentiation as targets of robber bees are four times more likely to have nest guards of increased size than non-targets. These findings reveal unexpected diversity in the social organization of stingless bees.

Xylanases from Aspergillus niger, Aspergillus niveus and Aspergillus ochraceus produced under solid-state fermentation and their application in cellulose pulp bleaching

Abstract: This study describes the production of xylanases from Aspergillus niveus, A. niger, and A. ochraceus under solid-state fermentation using agro-industrial residues as substrates. Enzyme production was improved using a mixture of wheat bran and yeast extract or peptone. When a mixture of corncob and wheat bran was used, xylanase production from A. niger and A. ochraceus increased by 18%. All cultures were incubated at 30 °C at 70–80% relative humidity for 96 h. For biobleaching assays, 10 or 35 U of xylanase/g dry cellulose pulp were incubated at pH 5.5 for 1 or 2 h, at 55 °C. The delignification efficiency was 20%, the brightness (percentage of ISO) increased two to three points and the viscosity was maintained confirming the absence of cellulolytic activity. These results indicated that the use of xylanases could help to reduce the amount of chlorine compounds used in cellulose pulp treatment.