Computer-Aided Solvent Screening for Biocatalysis

A computer-aidedsolventscreening methodology is described and tested for biocatalytic systems composed of enzyme, essential water and substrates/products dissolved in a solvent medium, without cells. The methodology is computationally simple, using group contribution methods for calculating constrained properties related to chemical reaction equilibrium, substrate and product solubility, water solubility, boiling points, toxicity and others. Two examples are provided, covering the screening of solvents for lipase-catalyzed transesterification of octanol and inulin with vinyl laurate. Esterification of acrylic acid with octanol is also addressed. Solvents are screened and candidates identified, confirming existing experimental results. Although the examples involve lipases, the method is quite general, so there seems to be no preclusion against application to other biocatalyst

Os níveis pertinentes para a pesquisa - ação sobre a gestão dos recursos naturais nas regiões de fronteira: o caso da Transamazônica

A busca atual de uma gestão adequada dos recursos naturais para o seu uso sustentável coloca a questão dos níveis mais pertinentes de pesquisa e de intervenção: estabelecimentos agrícolas, comunidades, ou coletividades locais, organizações formais, a região, estado como um todo? Ou, então, um espaço institucional de articulação destes diversos níveis? E em função de que critérios decidir? A partir de observações e da analise de resultados de uma pesquisa-ação desenvolvida dentro do Programa Agro-ecológico da Transamazônica – PAET, em parceria com o Movimento pela Sobrevivência na Transamazônica – MPST e uma equipe interdisciplinar de pesquisa-desenvolvimento – LAET, propõe-se estudar estas questões no contexto de uma área da fronteira agrícola amazônica aberta nos anos 1970, onde hoje predomina a agricultura familiar em que se pesem a instância de grandes fazendas de criação bovina e uma forte tendência à concentração fundiária. São examinados possíveis níveis de intervenção: o lote familiar, com possibilidade de exploração mais intensiva e diversificada; a localidade, ainda que carente de maior coesão social; o município como espaço de interação de negociação da decisão, porém com limitada competência legislativa nas áreas fundiárias e ambientais; a região, enfim. A sugestão conclusiva seria de privilegiar o nível de estabelecimentos no plano de intervenções de natureza tecnológica, o município e a região no plano politico e institucional

Complex melting of semi-crystalline chicory (Cichorium intybus L.) root inulin

When concentrated solutions (30–45% by weight) of inulin (degree of polymerization 2–66, number average degree of polymerization 12) are cooled at 1 °C/min or 0.25 °C/min from 96 °C to 20 °C, suspensions of semi-crystalline material in water are formed. A thermal nucleation process was detected by optical microscopy: the 8-like shaped crystallites resulting from primary nucleation at higher temperature are larger than those resulting from secondary nucleation at lower temperature. Differential scanning calorimetry (DSC) thermograms display melting profiles with three to four partly overlapping endotherms that vary as a function of concentration, cooling rate during crystallization and storage time at 25 °C of the crystallite suspension. Recrystallization during melting was observed. The wide-angle X-ray scattering patterns of the samples at 25 °C correspond to those of the hydrated crystal polymorph. The structural changes during melting indicated the existence of a single crystal polymorph throughout melting. A periodicity of 95 Å, arising from alternating regions of different electron density, is detected in the small angle X-ray scattering patterns at 25 °C. The stepwise increase of the long period upon heating is related to the existence of two types of lamellar stacks: one with a higher long period, resulting from the primary nucleation and thus crystallized at high temperature, and a second one with a smaller long period, formed by crystallization at lower temperature. The lamellae formed at low temperature melt at a lower temperature than those formed at high temperature, explaining the existence of the two DSC-endotherms

Characterization of the physical state of spray-dried inulin.

Modulated differential scanning calorimetry, wide angle x-ray scattering, and environmental scanning electron microscopy were used to investigate the physical and morphological properties of chicory root inulin spray dried under different conditions. When the feed temperature increased up to 80 degrees C, the average degree of polymerization of the solubilized fraction increased, leading to a higher glass transition temperature (Tg). Above 80 degrees C, the samples were completely amorphous, and the Tg did not change. The starting material was semicrystalline, and the melting region was composed of a dual endotherm; the first peak subsided as the feed temperature increased up to a temperature of 70 degrees C, whereas above 80 degrees C, no melting peak was observed as the samples were completely amorphous. To a lesser extent, the inlet air temperature of 230 degrees C allowed a higher amorphous content of the samples than at 120-170 degrees C but induced a blow-out of the particles