Chitosan as flocculant agent for clarification of stevia extract

Stevia is used as a sweetener due to its low calorific value and its taste, which is very similar to that of sucrose. After extraction from dried leaves, stevia extract is dark in colour, and therefore needs to be whitened to increase acceptance by consumers. In this study we tested chitosan, a cationic polyelectrolyte, as flocculant agent for the whitening of the Stevia extract. Positive charges of chitosan can interact electrostatically with a counter-ion, sodium tripolyphosphate (TPP), and then chitosan precipitates. A factorial design was used to study the whitening process, in which Glycosides Removal, Colour Removal, Turbidity Removal and Soluble Solids Removal were evaluated. The studied factors were Chitosan Mass and pH of the TPP solution. The results showed that chitosan is a good flocculant agent, being able to flocculate both the glycosides and the pigments that make the extract coloured.UNIOESTE Centro de Engenharias e Ciências ExatasUNIFESP Centro de Ciências Exatas e da TerraUNIFESP, Centro de Ciências Exatas e da TerraSciEL

Crescimento de plantulas da especie invasora Calotropis procera em solos de campos rupestres ferruginosos e floresta seca sazonal

The present study evaluated the growth, biomass allocation and nutrient content in seedlings of the invasive and exotic especies Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), cultured in greenhouse, in soils from two different ecosystems: ironstone rupestrian fields (Canga) of Brumadinho, Minas Gerais; and seasonally dry forest (Caatinga), of Serra Talhada, Pernambuco. Seedlings from the Canga treatment were significantly higher in concern to stem length, leaf biomass and total biomass. In respect to nutrient content there were higher phosphorus, iron and zinc levels in the seedlings from the Canga treatment. The iron accumulation indicates the capacity of C. procera to tolerate high levels of iron, which is characteristic of Canga soils. In the Caatinga treatment there was a higher root/ shoot ratio and a higher potassium accumulation in the plant tissues. The obtained results suggest that C. procera displays a good adaptation to the edaphic conditions of the Canga treatment, which indicates an invasive potential towards the Canga ecosystem. Key words: Caatinga, Calotropis procera, Canga, early growth, invasion.O presente estudo avaliou o crescimento, a alocação de biomassa e os teores de nutrientes em plântulas da espécie exótica e invasora Calotropis procera (Aiton) W.T. Aiton (Apocynaceae), cultivadas em casa de vegetação, em solos provenientes de dois ecossistemas distintos: campo rupestre ferruginoso (Canga, Brumadinho, Minas Gerais) e floresta seca sazonal (Caatinga, Serra Talhada, Pernambuco). Plântulas do tratamento Canga foram significativamente maiores em relação ao comprimento do caule, biomassa de folhas e biomassa total. Em relação aos teores de nutrientes, houve maior teor de fósforo, ferro e zinco nos tecidos de plântulas do tratamento Canga. O acumulo de ferro indica a capacidade de C. procera em tolerar os altos teores de ferro característicos dos solos de Canga. No tratamento Caatinga, houve uma maior razão raiz-ramo e maior acúmulo de potássio em seus tecidos. Os resultados obtidos sugerem que C. procera demonstra boa adaptação às condições dos solos do tratamento Canga, indicando um potencial para invasão no ecossistema de Canga. Palavras-chave: Caatinga, Calotropis procera, Canga, crescimento inicial, invasão biológica

Phase Transition in Liquid Drop Fragmentation

A liquid droplet is fragmented by a sudden pressurized-gas blow, and the resulting droplets, adhered to the window of a flatbed scanner, are counted and sized by computerized means. The use of a scanner plus image recognition software enables us to automatically count and size up to tens of thousands of tiny droplets with a smallest detectable volume of approximately 0.02 nl. Upon varying the gas pressure, a critical value is found where the size-distribution becomes a pure power-law, a fact that is indicative of a phase transition. Away from this transition, the resulting size distributions are well described by Fisher's model at coexistence. It is found that the sign of the surface correction term changes sign, and the apparent power-law exponent tau has a steep minimum, at criticality, as previously reported in Nuclear Multifragmentation studies [1,2]. We argue that the observed transition is not percolative, and introduce the concept of dominance in order to characterize it. The dominance probability is found to go to zero sharply at the transition. Simple arguments suggest that the correlation length exponent is nu=1/2. The sizes of the largest and average fragments, on the other hand, do not go to zero but behave in a way that appears to be consistent with recent predictions of Ashurst and Holian [3,4].Comment: 10 pages, 11 figures. LaTeX (revtex4) with psfig/epsfi

Foraminifera on coral reefs of Brazil: the FOCO project

Abstrac

Liquid-Ordered Phase Formation by Mammalian and Yeast Sterols: A Common Feature With Organizational Differences

Here, biophysical properties of membranes enriched in three metabolically related sterols are analyzed both in vitro and in vivo. Unlike cholesterol and ergosterol, the common metabolic precursor zymosterol is unable to induce the formation of a liquid ordered (lo) phase in model lipid membranes and can easily accommodate in a gel phase. As a result, Zym has a marginal ability to modulate the passive membrane permeability of lipid vesicles with different compositions, contrary to cholesterol and ergosterol. Using fluorescence-lifetime imaging microscopy of an aminostyryl dye in living mammalian and yeast cells we established a close parallel between sterol-dependent membrane biophysical properties in vivo and in vitro. This approach unraveled fundamental differences in yeast and mammalian plasma membrane organization. It is often suggested that, in eukaryotes, areas that are sterol-enriched are also rich in sphingolipids, constituting highly ordered membrane regions. Our results support that while cholesterol is able to interact with saturated lipids, ergosterol seems to interact preferentially with monounsaturated phosphatidylcholines. Taken together, we show that different eukaryotic kingdoms developed unique solutions for the formation of a sterol-rich plasma membrane, a common evolutionary trait that accounts for sterol structural diversity.Peer Reviewe

Effects of pollen collection on colony development and in the bromatological composition Apis mellifera L. pupae

Africanized bees (Apis mellifera L.) were studied in the Botucatu region (São Paulo State), Brazil, from August to November, 1996, with the objective of quantifying pollen trapping and its effects on colony development and composition of worker bee pupae. Mean trapped pollen yield was 1.47 kg/beehive. Trapping had little effect on brood production, causing only a 9.7% reduction in total worker brood area and a 4.0% reduction in drone brood area, as compared to the treatment without pollen types. Pollen harvest did not affect the bromatological composition of worker pupae (white bodies and slightly pigmented eyes), mean values obtained for both treatments being 18.87% dry matter, 48.07% crude protein, 18.52% ether extract and 3.72% ash

Prospective, randomized trial comparing fluids and dobutamine optimization of oxygen delivery in high-risk surgical patients [ISRCTN42445141]

INTRODUCTION: Preventing perioperative tissue oxygen debt contributes to a better postoperative recovery. Whether the beneficial effects of fluids and inotropes during optimization of the oxygen delivery index (DO(2)I) in high-risk patients submitted to major surgeries are due to fluids, to inotropes, or to the combination of the two is not known. We aimed to investigate the effect of DO(2)I optimization with fluids or with fluids and dobutamine on the 60-day hospital mortality and incidence of complications. METHODS: A randomized and controlled trial was performed in 50 high-risk patients (elderly with coexistent pathologies) undergoing major elective surgery. Therapy consisted of pulmonary artery catheter-guided hemodynamic optimization during the operation and 24 hours postoperatively using either fluids alone (n = 25) or fluids and dobutamine (n = 25), aiming to achieve supranormal values (DO(2)I > 600 ml/minute/m(2)). RESULTS: The cardiovascular depression was an important component in the perioperative period in this group of patients. Cardiovascular complications in the postoperative period occurred significantly more frequently in the volume group (13/25, 52%) than in the dobutamine group (4/25, 16%) (relative risk, 3.25; 95% confidence interval, 1.22–8.60; P < 0.05). The 60-day mortality rates were 28% in the volume group and 8% in the dobutamine group (relative risk, 3.00; 95% confidence interval, 0.67–13.46; not significant). CONCLUSION: In patients with high risk of perioperative death, pulmonary artery catheter-guided hemodynamic optimization using dobutamine determines better outcomes, whereas fluids alone increase the incidence of postoperative complications

Bromatological and mineral compositions of collected pollen for africanized honeybees (Apis mellifera L.) in Botucatu, São Paulo State

The bromatological and mineral compositions of pollen collected by Africanized honeybees (Apis mellifera L.) in the Botucatu region, São Paulo State, Brazil, from August to November, 1966, were investigated. The pollen collections from six beehives, at weekly intervals, lasted for seven consecutive days. Mean fresh pollen composition was: 75.9% dry matter, 26.2% crude protein (CP), 5.1% ether extract (EE), 2.6% ash, 1.1% crude fiber, 3.58% nitrogen, 0.43% phosphorus, 0.67% potassium, 0.26% calcium, 0.08% magnesium, 0.21% sulfur, 114.2 ppm iron, 88.4 ppm zinc, 15.0 ppm copper, 32.4 ppm manganese, and 9.9 ppm boron. Statistical analysis showed that pollen collected in October had the highest contents of CP, and of the elements P, S and Mn compared to the other months. According to cluster and principal components analyses for bromatological composition, the variables with most and least discriminatory power were the percentages of CP and EE, respectively. As to mineral composition, the most discriminatory variables were S, Mn, and N, while the least discriminatory were Mg, B, and K