Imobilização de lacase de Aspergillus sp. em quitosana e sua aplicação na bioconversão de fenóis em reatores de leito fixo

The immobilization of laccase on chitosan by cross-linking and application of the immobilized laccase in the bioconversion of phenolic compounds in batch and fixed bed reactors were studied. The process for immobilization of enzyme was optimized using a rotational central composite design. The optimized conditions to generate immobilized laccase with maximal activity were determined to be a glutaraldehyde concentration of 1.0% (v/v), a pH of 6.0, an immobilization time of 5.0 hours and an enzyme concentration of 5.2 g L-1. In packed bed reactors, the activity of the immobilized enzyme is maintained for a longer time in the bioconversion of 2,6-dimethoxyphenol than in the bioconversion of syringaldazine.

Production of isomaltulose obtained by Erwinia sp. cells submitted to different treatments and immobilized in calcium alginate

In recent decades, there has been an increase in the studies of isomaltulose obtainment, due to its physicochemical properties and physiological health benefits. These properties, which include low cariogenicity, low glycemic index and greater stability, allow the use of this sweetener as a substitute for sucrose in foods; besides the fact that it can be converted to isomalt, a dietary non-cariogenic sugar alcohol used in pharmaceuticals as well as in the food industry. Isomaltulose (6-O-α-D-glucopyronosyl-1-6-D-fructofuranose) is a disaccharide reducer obtained by the enzymatic conversion of sucrose - the α-glucosyltransferase enzyme. Different treatments were performed for the preparation of whole cells; lysed cells; and crude enzyme extract of Erwinia sp. D12 strain immobilized in calcium alginate. The packed bed column of granules, containing Erwinia sp. cells sonicated and immobilized in calcium alginate (CSI), reached a maximum conversion of 53-59% sucrose into isomaltulose and it presented activity for 480 hours. The converted syrup was purified and the isomaltulose crystallization was performed through the lowering of temperature. The isomaltulose crystals presented purity of 96.5%.

Air blast freezing of fruit pulp models in commercial boxes: influence of preferential channels in the bed on freezing times estimating

The freezing times of fruit pulp models packed and conditioned in multi-layered boxes were evaluated under conditions similar to those employed commercially. Estimating the freezing time is a difficult practice due to the presence of significant voids in the boxes, whose influence may be analyzed by means of various methods. In this study, a procedure for estimating freezing time by using the models described in the literature was compared with experimental measurements by collecting time/temperature data. The following results show that the airflow through packages is a significant parameter for freezing time estimation. When the presence of preferential channels was considered, the predicted freezing time in the models could be 10% lower than the experimental values, depending on the method. The isotherms traced as a function of the location of the samples inside the boxes showed the displacement of the thermal center in relation to the geometric center of the product.

Aeromonas spp. isolated from oysters (Crassostrea rhizophorea) from a natural oyster bed, Ceará, Brazil

Between April and October 2002, thirty fortnightly collections of oysters (Crassostrea rhizophorea) from a natural oyster bed at the Cocó River estuary in the Sabiaguaba region (Fortaleza, Ceará, Brazil) were carried out, aiming to isolate Aeromonas spp. strains. Oyster samples were submitted to the direct plating (DP) and the presence/absence (P/A) methods. Aeromonas were identified in 15 (50%) samples analyzed by the DP method and in 13 (43%) analyzed by the P/A method. A. caviae, A. eucrenophila, A. media, A. sobria, A. trota, A. veronii bv. sobria, A. veronii bv. veronii and Aeromonas sp. were isolated. The predominant species was A. veronii (both biovars), which was identified in 13 (43%) samples, followed by A. media in 11 (37%) and A. caviae in seven (23%). From the 59 strains identified, 28 (48%) presented resistance to at least one of the eight antibiotics tested.

INSECTICIDE-TREATED BED NETS IN RONDÔNIA, BRAZIL: EVALUATION OF THEIR IMPACT ON MALARIA CONTROL

Mosquito nets treated with long-lasting insecticide (LLINs), when used in compliance with guidelines of the World Health Organization, may be effective for malaria vector control. In 2012, approximately 150,000 LLINs were installed in nine municipalities in the state of Rondônia. However, no studies have assessed their impact on the reduction of malaria incidence. This study analyzed secondary data of malaria incidence, in order to assess the impact of LLINs on the annual parasite incidence (API). The results showed no statistically significant differences in API one year after LLIN installation when compared to municipalities without LLINs. The adoption of measures for malaria vector control should be associated with epidemiological studies and evaluations of their use and efficiency, with the aim of offering convincing advantages that justify their implementation and limit malaria infection in the Amazon Region.

Efficacy of insecticide impregnated bed-nets to control malaria in a rural forested area in Southern Cameron

Due to current spreading of chemoresistant strains of Plasmodium falciparum malaria control must incorporate vector control programmes. Due to well known constraints house sprayings cannot be performed as before. Personal protection can be developed and a large scale use of insecticide treated bed-nets appeared to be very useful to reduce man-vector contact in Asia, South America and West and East Africa. No trial has done is forest Central Africa where transmission is permanent. We performed such a trial in the southern part of Cameroon (using deltamethrin, at 25mg/m*) and obtained similar data to those observed in the Gambia Burkina Faso and Tanzania with a noteworthy reduction of both transmission and high parasitaemia of P. falciparum (respectively 78% and 75%) meaning a drop of malaria morbidity.

Effect of untreated bed nets on blood-fed Phlebotomus argentipes in kala-azar endemic foci in Nepal and India

Observational studies in the Indian subcontinent have shown that untreated nets may be protective against visceral leishmaniasis (VL). In this study, we evaluated the effect of untreated nets on the blood feeding rates of Phlebotomus argentipes as well as the human blood index (HBI) in VL endemic villages in India and Nepal. The study had a "before and after intervention" design in 58 households in six clusters. The use of untreated nets reduced the blood feeding rate by 85% (95% CI 76.5-91.1%) and the HBI by 42.2% (95% CI 11.1-62.5%). These results provide circumstantial evidence that untreated nets may provide some degree of personal protection against sand fly bites.

Nutritional potential of green banana flour obtained by drying in spouted bed

This study evaluated the chemical composition of peeled and unpeeled green banana Cavendish (AAA) flour obtained by drying in spouted bed, aiming at adding nutritional value to food products. The bananas were sliced and crushed to obtain a paste and fed to the spouted bed dryer (12 cm height and T = 80 ºC) in order to obtain flour. The flours obtained were subjected to analysis of moisture, protein, ash, carbohydrates, total starch, resistant starch, fiber. The green banana flours, mainly unpeeled, are good sources of fiber and resistant starch with an average of 21.91g/100g and 68.02g/100g respectively. The protein content was found in an average of 4.76g/100g, being classified as a low biological value protein with lysine as the first limiting amino acid. The results showed that unpeeled green banana flour obtained by spouted bed drying can be a valuable tool to add nutritional value to products in order to increase their non-digestible fraction.

On-line preconcentration system using a microcolumn packed with Alizarin Red S-modified alumina for zinc determination by flame atomic absorption spectrometry

A simple and sensitive on-line flow injection system for determination of zinc with FAAS has been described. The method is based on the separation and preconcentration of zinc on a microcolumn of immobilized Alizarin Red S on alumina. The adsorbed analyte is then eluted with 250 µL of nitric acid (1 mol L-1) and is transported to flame atomic absorption spectrometer for quantification. The effect of pH, sample and eluent flow rates and presence of various cations and anions on the retention of zinc was investigated. The sorption of zinc was quantitative in the pH range of 5.5-8.5. For a sample volume of 25 mL an enrichment factor of 144 and a detection limit (3S) of 0.2 µg L-1 was obtained. The precision (RSD, n=7) was 3.0% at the 20 µg L-1 level. The developed system was successfully applied to the determination of zinc in water samples, hair, urine and saliva.

Super/subcritical fluid chromatography with packed columns: state of the art and applications

Separations using supercritical fluid chromatography (SFC) with packed columns have been re-discovered and explored in recent years. SFC enables fast and efficient separations and, in some cases, gives better results than high performance liquid chromatography (HPLC). This paper provides an overview of recent advances in SFC separations using packed columns for both achiral and chiral separations. The most important types of stationary phases used in SFC are discussed as well as the most critical parameters involved in the separations and some recent applications.

Energetic efficiency of a deep bed swine production system

The aim of this work was to evaluate the energy flows of a commercial production system of swine deep bed in its finishing phase, located in Juiz de Fora, in the State of Minas Gerais, Brazil. Thus, an energy efficiency study was carried out by monitoring a lot of animals, during a 94-day period. The energy rate of each compound involved in the production process was quantified and the matrixes of energy consumption were determined in the form of animal feeding, electrical energy, piglets, material used as deep bed, human labor, equipment, swine buildings, production of alive swine for slaughter, organic fertilizer production (swine deep bed or swine deep litter). From the direct input energy, 80.57% correspond to animal feeding, 11.90% to pigs for slaughter and 6.76% to piglets, while from the energy output 53.45% correspond to the terminating swine and 46.55% to organic fertilizer (swine deep bed). By the results obtained, we can conclude that such production system has corresponded to an industrial and highly specialized agro ecosystem, importing a great part of the energy consumed in the production process, with 41% of energy efficiency.

Start-up of horizontal anaerobic reactors with sludge blanket and fixed bed for wastewater treatment from coffee processing by wet method

In this study it was evaluated the start-up procedures of anaerobic treatment system with three horizontal anaerobic reactors (R1, R2 and R3), installed in series, with volume of 1.2 L each. R1 had sludge blanket, and R2 and R3 had half supporter of bamboo and coconut fiber, respectively. As an affluent, it was synthesized wastewater from mechanical pulping of the coffee fruit by wet method, with a mean value of total chemical oxygen demand (CODtotal) of 16,003 mg L-1. The hydraulic retention time (HRT) in each reactor was 30 h. The volumetric organic loading (VOL) applied in R1 varied from 8.9 to 25.0 g of CODtotal (L d)-1. The mean removal efficiencies of CODtotal varied from 43 to 97% in the treatment system (R1+R2+R3), stabilizing above 80% after 30 days of operation. The mean content of methane in the biogas were of 70 to 76%, the mean volumetric production was 1.7 L CH4 (L reactor d)-1 in the system, and the higher conversions were around at 0.20 L CH4 (g CODremoved)-1 in R1 and R2. The mean values of pH in the effluents ranged from 6.8 to 8.3 and the mean values of total volatile acids remained below 200 mg L-1 in the effluent of R3. The concentrations of total phenols of the affluent ranged from 45 to 278 mg L-1, and the mean removal efficiency was of 52%. The start-up of the anaerobic treatment system occurred after 30 days of operation as a result of inoculation with anaerobic sludge with active microbiota.

Hydrogen production from cassava processing wastewater in an anaerobic fixed bed reactor with bamboo as a support material

Attempting to associate waste treatment to the production of clean and renewable energy, this research sought to evaluate the biological production of hydrogen using wastewater from the cassava starch treatment industry, generated during the processes of extraction and purification of starch. This experiment was carried out in a continuous anaerobic reactor with a working volume of 3L, with bamboo stems as the support medium. The system was operated at a temperature of 36°C, an initial pH of 6.0 and under variations of organic load. The highest rate of hydrogen production, of 1.1 L.d-1.L-1, was obtained with application of an organic loading rate of 35 g.L-1.d-1, in terms of total sugar content and hydraulic retention time of 3h, with a prevalence of butyric and acetic acids as final products of the fermentation process. Low C/N ratios contributed to the excessive growth of the biomass, causing a reduction of up to 35% in hydrogen production, low percentages of H2 and high concentrations of CO2in the biogas.

Fluid dynamic modelling and simulation of circulating fluidized bed reactors: importance of the interface turbulence transfer

The main objective of this work is to analyze the importance of the gas-solid interface transfer of the kinetic energy of the turbulent motion on the accuracy of prediction of the fluid dynamic of Circulating Fluidized Bed (CFB) reactors. CFB reactors are used in a variety of industrial applications related to combustion, incineration and catalytic cracking. In this work a two-dimensional fluid dynamic model for gas-particle flow has been used to compute the porosity, the pressure, and the velocity fields of both phases in 2-D axisymmetrical cylindrical co-ordinates. The fluid dynamic model is based on the two fluid model approach in which both phases are considered to be continuous and fully interpenetrating. CFB processes are essentially turbulent. The model of effective stress on each phase is that of a Newtonian fluid, where the effective gas viscosity was calculated from the standard k-epsilon turbulence model and the transport coefficients of the particulate phase were calculated from the kinetic theory of granular flow (KTGF). This work shows that the turbulence transfer between the phases is very important for a better representation of the fluid dynamics of CFB reactors, especially for systems with internal recirculation and high gradients of particle concentration. Two systems with different characteristics were analyzed. The results were compared with experimental data available in the literature. The results were obtained by using a computer code developed by the authors. The finite volume method with collocated grid, the hybrid interpolation scheme, the false time step strategy and SIMPLEC (Semi-Implicit Method for Pressure Linked Equations - Consistent) algorithm were used to obtain the numerical solution.