Effectiveness factor for immobilized biocatalysts: two substratestwo products reactions

Immobilized enzymes are being increasingly used as biocatalysts in numerous processes to obtain high-value products for the pharmaceutical, flavour and fragrance industries (Gandhi et al., 2000). The major advantages of immobilization include the increase in enzyme stability, the possibility of enzyme reutilization and the easy separation of the biocatalysts from the reaction mixture. However, it is necessary to account for mass transfer limitations that, under some conditions, may arise in these systems (Gómez et al., 2003; Jeison et al., 2003). These resistances comprise the effects of intraparticle diffusion and external mass-transfer. Given the complexity of the kinetics of multisubstrate enzyme reactions, reactor modelling studies that account for mass-transfer phenomena are so far limited to single-substrate ones (Gómez et al., 2003). To compare the observed reaction rate with the reaction rate in the absence of mass-transfer limitations, an overall effectiveness factor is usually calculated (Gómez et al., 2003; Jeison et al., 2003). In this work, a model is developed to calculate the overall effectiveness factor for immobilized enzymes that carry out irreversible two substrates-two products reactions following kinetic mechanisms such as the Ternary Complex or the Ping-Pong Bi-Bi with inhibition by the second substrate. The model has two dimensionless parameters for each substrate – Thiele modulus (reaction/intraparticle diffusion), Biot number (film diffusion/intraparticle diffusion) – and one related to the reaction kinetics. Their influence on the effectiveness factor is analysed. The results obtained can be applied in the design and simulation of enzymatic reactors

Production of esters by biocatalysed transesterification in supercritical CO2 and Hexane

The development of sustainable processes that use renewable raw materials and minimize chemical and energetic waste has attracted considerable attention and represents a great challenge to both academic researchers and industrial experts. The use of enzymes to catalyse chemical transformations can constitute a more sustainable alternative to some traditional chemical processes and more than 100 biotransformations are already operated at an industrial scale [1]. Lipases usually operate in mild conditions and can catalyse both hydrolytic and synthetic reactions, depending on the surrounding medium. The hydrolysis of esters can be performed in water, but the reverse production reactions are not favoured in this medium, and are usually performed in organic solvents. Supercritical CO2 can constitute a more sustainable alternative to organic solvents as a reaction medium, provided that it does not have a direct adverse effect on the enzyme's active site or significantly reduce its activity. Decyl acetate was chosen as a model compound and its production by a transesterification reaction catalysed by Novozym 435 (immobilized Candida Antarctica Lipase B) was studied in both hexane and supercritical CO2. A comparative analysis between these two alternatives was performed, focusing on the differences on the enzyme's catalytic activity, solubilities of the substrates and mass transfer rates; which significantly affect the outcome of the reaction process and its productivity and provide information on when such solvents can be used. [1] Straathof, A.J.J., Panke, S., Schmid, A. The production of fine chemicals by biotransformations. Current Opinion in Biotechnology, 2002, 13(6), 548-556

A MODIS-based energy balance to estimate evapotranspiration for clear-sky days in Brazilian tropical savannas

Evapotranspiration (ET) plays an important role in global climate dynamics and in primary production of terrestrial ecosystems; it represents the mass and energy transfer from the land to atmosphere. Limitations to measuring ET at large scales using ground-based methods have motivated the development of satellite remote sensing techniques. The purpose of this work is to evaluate the accuracy of the SEBAL algorithm for estimating surface turbulent heat fluxes at regional scale, using 28 images from MODIS. SEBAL estimates are compared with eddy-covariance (EC) measurements and results from the hydrological model MGB-IPH. SEBAL instantaneous estimates of latent heat flux (LE) yielded r 2= 0.64 and r2 = 0.62 over sugarcane croplands and savannas when compared against in situ EC estimates. At the same sites, daily aggregated estimates of LE were r 2 = 0.76 and r2 = 0.66, respectively. Energy balance closure showed that turbulent fluxes over sugarcane croplands were underestimated by 7% and 9% over savannas. Average daily ET from SEBAL is in close agreement with estimates from the hydrological model for an overlay of 38,100 km2 (r2 = 0.88). Inputs to which the algorithm is most sensitive are vegetation index (NDVI), gradient of temperature (dT) to compute sensible heat flux (H) and net radiation (Rn). It was verified that SEBAL has a tendency to overestimate results both at local and regional scales probably because of low sensitivity to soil moisture and water stress. Nevertheless the results confirm the potential of the SEBAL algorithm, when used with MODIS images for estimating instantaneous LE and daily ET from large areas

Desvantagens duplas: Estrutura institucional e vantagens compensatórias no ensino superior brasileiro

This paper examines the interaction between family income and academic performance in determining access to public and private higher education in Brazil during the expansionist period since the 1990s. The study aims to answer three questions: (a) how do family income and academic performance affect the likelihood of accessing higher education? (b) to what extent can low income be compensated for by good grades or vice versa? (c) how do these inequalities manifest in the division between public and private higher education? Using administrative data, we constructed a panel of high school graduates in 2012 who were followed for five years after completing secondary education. The results indicate that, for admission to public institutions, which are tuition-free and prestigious, academic performance is the most important predictor, and the advantage of wealthier students depends on their higher chances of obtaining better grades. In contrast, for entering private institutions, the socioeconomic gap is almost independent of grades, and privileged individuals have a higher chance of admission despite poor academic performance. We conclude that the horizontal stratification of the Brazilian education system shapes the occurrence of dual advantages for students from privileged backgrounds: compensatory advantages in accessing the private sector and cumulative advantages in accessing the public sector, due to their respective privileges of origin and probabilities of obtaining higher grades.Este artículo examina la relación entre la renta familiar y el rendimiento académico en el acceso a la educación superior pública y privada en Brasil desde la década de 1990. Se plantean tres preguntas clave: (a) ¿Cómo influyen los ingresos familiares y el rendimiento académico en la probabilidad de acceder a la educación superior? (b) ¿En qué medida se pueden compensar los bajos ingresos con buenas calificaciones o viceversa? (c) ¿Cómo se reflejan estas desigualdades en la división entre educación superior pública y privada? Utilizando datos administrativos, se construyó un panel de graduados de secundaria en 2012, y se les siguió durante cinco años tras completar la educación secundaria. Los resultados indican que el rendimiento académico es el factor más importante para la admisión en instituciones públicas, las cuales son gratuitas y prestigiosas, y la ventaja de los estudiantes más ricos radica en sus mayores posibilidades de obtener mejores calificaciones. Por otro lado, para ingresar a instituciones privadas, la brecha socioeconómica es casi independiente de las calificaciones, y los estudiantes privilegiados tienen mayores probabilidades de admisión a pesar de un bajo rendimiento académico. En conclusión, la estratificación horizontal de la educación brasileña estructura la aparición de ventajas duales para los estudiantes de origen privilegiado: ventajas compensatorias en el acceso al sector privado y ventajas acumulativas en el acceso al sector público, debido, respectivamente, a sus privilegios de origen y a sus probabilidades de obtener calificaciones más altas.Este trabalho discute a interação entre origem social e desempenho escolar nas probabilidades de acesso ao ensino superior no Brasil no auge da política expansionista que caracterizou o sistema educacional brasileiro desde a década de 1990. Especificamente, procuramos responder três perguntas: (a) como renda familiar e desempenho se combinam na estruturação das chances de acesso dos jovens? (b) até que ponto a nota pode compensar uma renda baixa ou, ao contrário, a renda familiar compensar desempenhos insuficientes na prova? (c) como essas desigualdades se articulam com a segmentação do ensino superior entre os setores público e privado? Os dados derivam de um painel de egressos do ensino médio em 2012 acompanhados por cinco anos após a conclusão da educação básica, com base em cruzamentos de registros administrativos. Os resultados indicam que para o acesso ao setor público - majoritariamente gratuito e composto por instituições academicamente seletivas - o desempenho é o preditor mais importante, independentemente da origem socioeconômica do candidato. O mesmo não se pode dizer do acesso a instituições privadas que, além de apresentar forte hiato socioeconômico, permite que estudantes nos estratos mais altos de renda tenham elevadas chance de acessá-lo ainda que apresentem os piores desempenhos. Concluímos que a estratificação horizontal da educação brasileira estrutura a ocorrência de vantagens duplas para estudantes de origem privilegiada: vantagens compensatórias no acesso ao setor privado e vantagens cumulativas no acesso ao setor público, em razão, respectivamente, de seus privilégios de origem e de suas probabilidades de obter maiores notas

Genomic variations in patients with myelodysplastic syndrome and karyotypes without numerical or structural changes

Myelodysplastic syndrome (MDS) is an onco-hematologic disease with distinct levels of peripheral blood cytopenias, dysplasias in cell differentiation and various forms of chromosomal and cytogenomic alterations. In this study, the Chromosomal Microarray Analysis (CMA) was performed in patients with primary MDS without numerical and/or structural chromosomal alterations in karyotypes. A total of 17 patients was evaluated by GTG banding and eight patients showed no numerical and/or structural alterations. Then, the CMA was carried out and identified gains and losses CNVs and long continuous stretches of homozygosity (LCSHs). They were mapped on chromosomes 1, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 16, 17, 18, 19, 20, 21, X, and Y. Ninety-one genes that have already been implicated in molecular pathways important for cell viability were selected and in-silico expression analyses demonstrated 28 genes differentially expressed in mesenchymal stromal cells of patients. Alterations in these genes may be related to the inactivation of suppressor genes or the activation of oncogenes contributing to the evolution and malignization of MDS. CMA provided additional information in patients without visible changes in the karyotype and our findings could contribute with additional information to improve the prognostic and personalized stratification for patients

Impact of Environment and Social Gradient on Leptospira Infection in Urban Slums

Leptospirosis, a life-threatening zoonotic disease, has become an important urban slum health problem. Epidemics of leptospirosis now occur in cities throughout the developing world, as the growth of slum settlements has produced conditions for rat-borne transmission of this disease. In this prevalence survey of more than 3,000 residents from a favela slum community in Brazil, Geographical Information System (GIS) and modeling approaches identified specific deficiencies in the sanitation infrastructure of slum environments—open sewers, refuse, and inadequate floodwater drainage—that serve as sources for Leptospira transmission. In addition to the environmental attributes of the slum environment, low socioeconomic status was found to independently contribute to the risk of infection. These findings indicate that effective prevention of leptospirosis will need to address the social factors that produce unequal health outcomes among slum residents, in addition to improving sanitation

Transmissão de doença de Chagas por transplante renal

Our objective is to report the case of a male patient submitted to kidney transplant from a living donor infected with Trypanosoma cruzi. The patient developed clinical manifestations of acute Chagas disease in the second post-transplant month and was successfully treated with benzonidazole. We discuss the possible means of transmission of Trypanosoma cruzi, the importance of its transmission to transplantation of solid organs, and the approach to this situation.Paciente submetido a transplante renal com órgão de doador vivo infectado pelo Tripanossoma cruzi e que desenvolve manifestações clínicas de doença de Chagas aguda no segundo mês pós- transplante, sendo tratado com sucesso com benzonidazol. Discutem-se as vias de transmissão e relevância clínica na transplantação de órgãos sólidos assim como as atitudes a serem tomadas diante desta situação

Transmission of Chagas disease in renal transplantation

Paciente submetido a transplante renal com órgão de doador vivo infectado pelo Tripanossoma cruzi e que desenvolve manifestações clínicas de doença de Chagas aguda no segundo mês pós- transplante, sendo tratado com sucesso com benzonidazol. Discutem-se as vias de transmissão e relevância clínica na transplantação de órgãos sólidos assim como as atitudes a serem tomadas diante desta situação.Our objective is to report the case of a male patient submitted to kidney transplant from a living donor infected with Trypanosoma cruzi. The patient developed clinical manifestations of acute Chagas disease in the second post-transplant month and was successfully treated with benzonidazole. We discuss the possible means of transmission of Trypanosoma cruzi, the importance of its transmission to transplantation of solid organs, and the approach to this situation