Qualidade da vinculação ao pai e à mãe e o desenvolvimento da amizade recíproca em crianças de idade pré-escolar

Estudos empíricos demonstraram que as crianças com uma vinculação mais segura com as figuras parentais são mais capazes de co-construir relações significativas com os pares, e que os relacionamentos afiliativos das crianças (em particular as amizades) parecem ter um grande impacto no desenvolvimento social ao longo da vida. Grande parte dos estudos têm-se centrado sobretudo na relação de vinculação com a mãe e não é claro qual o papel da vinculação com o pai no estabelecimento de relações próximas com os pares. O presente estudo examinou as relações entre a segurança da vinculação à mãe e ao pai aos 2,5 anos e o número de amizades da criança aos quatro anos. Participaram neste estudo 35 díades mãe-criança e pai-criança de famílias bi-parentais. A idade inicial das crianças variou entre 29 e 38 meses (M=31.75; DP=2.56), 23 eram raparigas. Ambos os progenitores trabalhavam fora de casa e as famílias pertenciam a um nível socio-económico médio. Para avaliar a segurança dos comportamentos de vinculação com ambos os pais foi utilizada a versão portuguesa do Attachment Behavior Q-Set (AQS) (Waters, 1995) aos 2,5 anos de idade. Para avaliar o número de amizades foram usadas duas técnicas sociométricas aos quatro anos de idade: 1) Método das Nomeações: (McCandless & Marshall, 1957), e 2) Escala de Apreciação (Asher, Singleton, Tinsley, & Hymel, 1979). Os resultados demonstraram uma consistência significativa nos comportamentos de base-segura da criança com os dois progenitores (r=.47, p<.05), e a uma correlação positiva entre comportamentos de base-segura com o pai e o posterior numero de amizades recíprocas da criança (r=.43, p<.05), o que sugere a existência de um efeito da interacção específica com o pai no estilo relacional da criança com os pares. Discutem-se os resultados argumentando que a vinculação segura ao pai pode ser uma condição necessária para o desenvolvimento de competências específicas na gestão da rede social das crianças em idade pré-escolar

Modeling and simulation of fructo-oligosaccharides production

It is foreseen that Systems Biology will have a great impact not only in Metabolic Engineering and Drug Discovery efforts, but also in Bioprocess development and optimization. In fact, the computational tools developed in this area made possible to simulate a biochemical process with a mathematical model comprising dynamical equations based on first principles as well as empirical kinetic equations and parameters that can be estimated from experimental data. Fructo-oligosaccharides (FOS) have become important as healthy food ingredients because of their beneficial characteristics to the health of human (Lee, 1999). They can be obtained biotechnologically using the enzyme Betafructofuranosidase, produced by some fungi. The main purpose of this work was to develop a mathematical model able to simulate the formation of FOS in a bioreactor, in order to perform a faster optimization of the FOS production process, allowing to identify which parameters can influence the final amount of FOS. An empirical model presented by Kow Jen Duan et al (1994) was used to obtain the first set of reactions. Several hydrolysis equations were added in order to achieve a general mathematical model of the occurring enzymatic reactions. After the reformulation of the Kow Jen Duan model, the kinetic parameters were determined from experimental data using the System Biology toolbox [2] with the Simulated Annealing method for curve fitting. Several experiments in bioreactors were performed with two different FOS producing fungi for that purpose. The time evolution of 7 state variables (Sucrose, Glucose, Fructose, 1-Kestose, Nystose, 1-Fructosyl Nystose and Biomass) was considered. After parameter fitting, several simulations were performed in MatLab and the simulation results were compared with experimental data, exhibiting a very satisfactory correlation for both fungal cultures. Correlation coefficients of 0.9980 - 0.9549 between simulated and experimental data were obtained. This model will be used to optimize the production process, using an optimization tool that has been developed in our research group

Optimization of a fructooligosaccharides purification method using activated charcoal

Fructooligosaccharides (FOS) have gained large commercial interest due to its beneficial properties in the human health as prebiotics. FOS are produced industrially by fermentative processes. However, the result of such fermentations is a complex mixture containing salts and approximately 50% (w/w) of low molecular weight sugars that have to be eliminated. Among other techniques that have been studied, the adsorption onto activated carbon is still the most suitable one since activated carbon is cheap, has a large surface area and pore volume conducting to a good sorption capacity. Furthermore, this sorbent can be regenerated during desorption with ethanol. Based on the above discussion, in this work the adsorption and desorption characteristics of FOS on activated carbon, using a gradient of ethanol, were optimized. Initially, the activated carbon was loaded with fermentative broth. To remove the non adsorbed sugars, a washing step with pure water was included. Afterwards, the retained sugars were recovered by elution with a gradient of ethanol increased sequentially with specific volumes from 1 to 50% (v/v). Fractions collected at different time points were evaporated and subsequently freeze‐dried. This process was found to be very efficient in the demineralization of broth, and it was possible to recover 80% of the initial FOS loaded on the column with 89% of purity. Some of the fractions were found to contain 97% of pure FOS in total sugars. In summary, purification of FOS using an activated charcoal column is a very efficient process yielding high levels of purity from a fermentative broth

Purification of fructo-oligosaccharides by adsorption onto charcoal filters

Production of fructo-oligosaccharides has received particular attention recently due to its beneficial effects as prebiotics. Fermentative processes appear to be a good technique for large scale production of FOS. However, the result of such fermentations is a complex mixture containing salts and low molecular weight sugars that do not contribute to the beneficial properties of the higher molecular weight oligosaccharides, and so have to be eliminated. Among the several strategies being studied to solve this problem, the adorption onto activated carbon is a promising technique that still requires further development. Thus, the aim of this work was the purification of FOS from a fermentation broth using charcoal filters. Microfiltration membranes (0,20 micrometers) were successfully used to separate the biomass; nevertheless salts and other small sugars had to be eliminated using a charcoal filter. Hence, 200 mL of fermentative broth (without cells) was passed through the filter. Subsequently, the filter was washed with water removing the salts and small sugars present in the mixture. The oligosaccharides adsorbed onto the charcoal filter were recovered using a 44% ethanol solution. An increased purity, from 30% to 97% (w/w) in total sugars, was achieved using this downstream process, as compared to the initial mixture. The results gathered in this work suggest that charcoal filters are a promising technology for the purification of FOS from fermentation mixtures at an industrial scale, making clear the need for further work in order to optimize this process

Aspectos anatómicos y fisiológicos de cultivos in vltro de Tropaeolum tuberosum (Ruiz and Pavón)

Se cultivaron explantes de peciolo de T. tuberosum en medio Murashíge and amp; Skoog suplementado con auxinas y citoquininas. Se describe la formación de callo y la regeneración de organoídes semejantes a raíces obtenidos a partir del subcultivo. Vástagos obtenidos mediante micropropagación, se incubaron a temperaturas de 18°e y 22°e, en medio MS para enraizamiento,observándose diferencias notorias en la morfología de las raíces.Petiole explants of T. tuberosum were cultivated in Murashíge and amp; Skoog medium suplemented with auxins and cítokíníns. Callus formation and abnormal morphogenesís obtained from subcuItures are described. Shoots obtained by micropropagation were incubated at 18°e and 22°e in medium MS for rooting. Notorius differences in root morphology were observed