750 resultados para Education -- Effect of technological innovations on


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This study aimed to evaluate the effects of physical exercise on body weight reduction. For 12 weeks, 22 obese women (BMI>30 kg/m(2)) were submitted to a physical exercise program. At the beginning and at the final of the program there were evaluated: BMI, waist (WC) and hip circumferences (HC), and waist-hip ratio (WHR); body composition by DEXA; hemoglobin and erythroctye, total cholesterol, HDL and LDL, triacylglycerol and blood glucose; aerobic power. At the final of the program, aerobic power, hemoglobin and erythrocyte values were significantly increased, confirming the physical training effects. Related to anthropometric values, only the visceral fat (WC, HC and WHR) were reduced. The exercise shows to be an important supporting in the body weight loss program, not exactly promoting body weight loss, but lowering risk factors to develop chronic diseases.

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Potassium oxalate desensitizers were previously shown to effectively reduce the immediate permeability of resin-bonded dentin. The current study evaluated whether the effect of the combined application of oxalate with etch-and-rinse adhesives interferes with the durability of resin-dentin bonds when using etch-and-rinse adhesives. The bond strength of resin-bonded dentin specimens composed of two-step or three-step etch-and-rinse adhesives (Single Bond, One-Step and Scotchbond Multi-Purpose, respectively) was tested immediately (24 hours) and after 12 months of water storage. The adhesives were used either according to the manufacturers` instructions (control groups) or after treating acid-etched dentin with a potassium oxalate gel (BisBlock, BISCO, Inc). The treatment of dentin with potassium oxalate was shown to negatively affect the baseline bond strength of resin-bonded dentin specimens, regardless of the adhesive used (p<0.05). After storage, the bond strength of the resin-bonded interfaces was significantly reduced for all the tested groups (p<0.001). Nevertheless, the rate of decreasing bond strength was significantly lower for oxalate-treated specimens than for the controls (p<0.05).

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The aim of this study was to examine the influence of the performance level of athletes on pacing strategy during a simulated 10-km running race, and the relationship between physiological variables and pacing strategy. Twenty-four male runners performed an incremental exercise test on a treadmill, three 6-min bouts of running at 9, 12 and 15 km h(-1), and a self-paced, 10-km running performance trial; at least 48 h separated each test. Based on 10-km running performance, subjects were divided into terziles, with the lower terzile designated the low-performing (LP) and the upper terzile designated the high-performing (HP) group. For the HP group, the velocity peaked at 18.8 +/- A 1.4 km h(-1) in the first 400 m and was higher than the average race velocity (P < 0.05). The velocity then decreased gradually until 2,000 m (P < 0.05), remaining constant until 9,600 m, when it increased again (P < 0.05). The LP group ran the first 400 m at a significantly lower velocity than the HP group (15.6 +/- A 1.6 km h(-1); P > 0.05) and this initial velocity was not different from LP average racing velocity (14.5 +/- A 0.7 km h(-1)). The velocity then decreased non-significantly until 9,600 m (P > 0.05), followed by an increase at the end (P < 0.05). The peak treadmill running velocity (PV), running economy (RE), lactate threshold (LT) and net blood lactate accumulation at 15 km h(-1) were significantly correlated with the start, middle, last and average velocities during the 10-km race. These results demonstrate that high and low performance runners adopt different pacing strategies during a 10-km race. Furthermore, it appears that important determinants of the chosen pacing strategy include PV, LT and RE.

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The objective of this research was to improve Glucose-6-phosphate dehydrogenase (G6PD) production by Saccharomyces cerevisiae W303-181, which carry the plasmid YEpPGK-G6PD, by varying the following cultivation conditions: pH value (4.8, 5.7 and 6.6); inoculum concentration (0.1, 0.6 and 1.1 g/L) and initial glucose concentration (20.0, 30.0 and 40.0 g/L). The effect of those variables on G6PD production capability was studied by the application of response surface statistical analysis. The results showed that the highest G6PD production (1594.2 U/L), specific activity (1189.7 U/g(cell)) and productivity (45.6 U/L.h) occurred at pH 4.8, inoculum concentration of 0.1 g/L and initial glucose concentration of 20.0 g/L, under agitation of 150 rpm at 30 degrees C after 36 h. In this work, the strain expressed about 21 fold more activity than the wild S. cerevisiae strain, being an attractive and promising new source of this enzyme.

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The objective of this work was to evaluate the influence of bioglass additions on the sintering and mechanical properties of yttria-stabilized zirconia ceramics, Y-TZP Samples containing different bioglass additions, varying between 0 and 30 wt.%, were cold uniaxial pressed at 80 MPa and sintered in air at 1200 degrees C or 1300 degrees C for 120 min. Sintered samples were characterized by X-ray Diffractometry and Scanning Electron Microscopy. Hardness and fracture toughness were determined using Vickers indentation method. As a preliminary biological evaluation, in vitro cytotoxicity tests by Neutral Red Uptake method (using mouse connective tissue cells, NCTC clone L929 from ATCC bank) were realized to determine the cytotoxicity level of ZrO(2)-bioglass ceramics. The increasing of bioglass amount leads to the decreasing of relative density due to martensitic (tetragonal-monoclinic) transformation during cooling of the sintered samples. Y-TZP samples sintered at 1300 degrees C containing 5 wt.% of bioglass presented the best results. with high relative density, hardness and fracture toughness of 11.3 GPa and 6.1 MPa m(1/2), respectively. Furthermore, the un-cytotoxic behavior was observed in all sintering conditions and bioglass amounts used in this study. (C) 2009 Elsevier B.V. All rights reserved.

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The objective of the present research was to evaluate the effect of fibre morphology (e.g., length, width, fibrillation, broken ends, content of fines and number of fibres per gram) on flocculation and drainage properties of fibre-cement suspensions and on physical properties of the fibre-cement composites. Mechanical refining was used to change the morphological properties of Eucalyptus and Pinus pulps. Results show that the mechanical refining increased the size of the formed flocs and decreased the concentration of free small particles (with dimensions between 1 and 20 pm) as a consequence of the increased fibrillation and content of fines, which increased the capacity of the fibres to capture the mineral particles. High levels of refining were necessary for Pinus pulp to obtain cement retention values similar to those obtained by unrefined Eucalyptus pulp. This is due to the higher number of fibres per gram in Eucalyptus pulp than in Pinus pulp. Pulp refining improved the packing of the particles and, although decreased the drainage rate. it contributed to a less porous structure, which improved the microstructure of the composite. (C) 2009 Elsevier Ltd. All rights reserved.

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Geosynthetics interlayer systems are effective techniques to control reflective cracking in damaged pavements. It comprises the inclusion of nonwoven geotextiles between the damaged layer and the new overlay of the pavement to reduce the propagation of cracks and to extend pavement life. However, the success of this technique depends directly on the understanding of the geotextile`s behavior when impregnated with asphalt This paper evaluates different nonwoven geotextiles frequently used in anti-reflective cracking systems, focusing on initial stiffness gain and permeability reduction after asphalt impregnation. Fresh and impregnated samples of polyester and polypropylene nonwoven geotextiles were tested. Cationic rapid setting emulsified asphalt was used as asphalt binder. Wide-width tensile tests were carried out based on the specification of ABNT - NBR 12824 (1993). Water vapor transmission tests were conducted according to ASTM E 96M (2005). Results of tensile tests on impregnated geotextiles showed a significant increase on tensile strength values, probably due to the inter contact of the fibers. Results also showed high increase in strength values at strain levels less than 0.05% and decrease on stiffness gains with increase of strains. Water vapor transmission tests demonstrated that cationic asphalt emulsion applied on nonwoven geotextiles allows a drastic reduction in permeability values to turn nonwoven geotextiles into a low permeability barrier. (C) 2010 Elsevier Ltd. All rights reserved.

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Many lab-scale studies have been carried out regarding the effect of feed strategy on the performance of anaerobic sequencing batch reactors (ASBR); however, more detailed pilot-scale studies should be performed to assess the real applicability of this type of operation. Therefore, the objective of this work was to assess the effect of feed strategy or fill time in a 1-m(3) mechanically stirred pilot-scale sequencing batch reactor, treating 0.65 m(3) sanitary wastewater in 8-h cycles at ambient temperature. Two reactor configurations were used: one containing granular biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam as inert support (denominated anaerobic sequencing batch biofilm reactor (AnSBBR)). The reactors were operated under five distinct feed strategies, namely: typical batch and fed-batch for 25%, 50%, 75%, and 100% of the cycle length. Stirring frequency in the ASBR was 40 rpm with two flat-blade turbine impellers and 80 rpm in the AnSBBR with two helix impellers. The results showed that both the ASBR and AnSBBR when operated under typical batch, fed-batch for 50% and 75% of the cycle length, presented improved organic matter removal efficiencies, without significant differences in performance, thus showing important operational flexibility. In addition, the reactors presented operation stability under all conditions.

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Currently, there is an increasing demand for the production of biodiesel and, consequently, there will be an increasing need to treat wastewaters resulting from the production process of this biofuel. The main objective of this work was, therefore, to investigate the effect of applied volumetric organic load (AVOL) on the efficiency, stability, and methane production of an anaerobic sequencing batch biofilm reactor applied to the treatment of effluent from biodiesel production. As inert support, polyurethane foam cubes were used in the reactor and mixing was accomplished by recirculating the liquid phase. Increase in AVOL resulted in a drop in organic matter removal efficiency and increase in total volatile acids in the effluent. AVOLs of 1.5, 3.0, 4.5 and 6.0 g COD L(-1) day(-1) resulted in removal efficiencies of 92%, 81%, 67%, and 50%, for effluent filtered samples, and 91%, 80%, 63%, and 47%, for non-filtered samples, respectively, whereas total volatile acids concentrations in the effluent amounted to 42, 145, 386 and 729 mg HAc L(-1), respectively. Moreover, on increasing AVOL from 1.5 to 4.5 g COD L(-1) day(-1) methane production increased from 29.5 to 55.5 N mL CH(4) g COD(-1). However, this production dropped to 36.0 N mL CH(4) g COD(-1) when AVOL was increased to 6.0 g COD L(-1) day(-1), likely due to the higher concentration of volatile acids in the reactor. Despite the higher concentration of volatile acids at the highest AVOL, alkalinity supplementation to the influent, in the form of sodium bicarbonate, at a ratio of 0.5-1.3 g NaHCO(3) g COD (fed) (-1) , was sufficient to maintain the pH near neutral and guarantee process stability during reactor operation.

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The effect of different precracking methods on the results of linear elastic K(Ic) fracture toughness testing with medium-density polyethylene (MDPE) was investigated. Cryogenic conditions were imposed in order to obtain valid K(Ic) values from specimens of suitable size. Most conservative K(Ic) values were obtained by slow pressing a fresh razor blade at the notch root of the specimen. Due to the low deformation level imposed on the crack tip region, the slow pressing razor blade technique also produced less scatter in fracture toughness results. It has been shown that the slow stable crack growth preceding catastrophic brittle failure during K(Ic) tests in MOPE under cryogenic conditions should not be disregarded as it has relevant physical meaning and may affect the fracture toughness results. (C) 2010 Elsevier Ltd. All rights reserved.

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Before one models the effect of plastic deformation on magnetoacoustic emission (MAE), one must first treat non-180 degrees domain wall motion. In this paper, we take the Alessandro-Beatrice-Bertotti-Montorsi (ABBM) model and modify it to treat non-180 degrees wall motion. We then insert a modified stress-dependent Jiles-Atherton model, which treats plastic deformation, into the modified ABBM model to treat MAE and magnetic Barkhausen noise (HBN). In fitting the dependence of these quantities on plastic deformation, we apply a model for when deformation gets into the stage where dislocation tangles are formed, noting two chief effects, one due to increased density of emission centers owing to increased dislocation density, and the other due to a more gentle increase in the residual stress in the vicinity of the dislocation tangles as deformation is increased.

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BACKGROUND: The use of the volatile salt ammonium carbamate in protein downstream processing has recently been proposed. The main advantage of using volatile salts is that they can be removed from precipitates and liquid effluents through pressure reduction or temperature increase. Although previous studies showed that ammonium carbamate is efficient as a precipitant agent, there was evidence of denaturation in some enzymes. In this work, the effect of ammonium carbamate on the stability of five enzymes was evaluated. RESULTS: Activity assays showed that alpha-amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1), lysozyme (1,4-beta-N-acetylmuramoylhydrolase, EC 3.2.1.17) and lipase (triacyl glycerol acyl hydrolase, EC 3.1.1.3) did not undergo activity loss in ammonium carbamate solutions with concentrations from 1.0 to 5.0 mol kg(-1), whereas cellulase complex (1,4-(1,3 : 14)-beta-D-glucan 4-glucano-hydrolase, EC 3.2.1.4) and peroxidase (hydrogen peroxide oxidoreductase, EC 1.11.1.7) showed an average activity loss of 55% and 44%, respectively. Precipitation assays did not show enzyme denaturation or phase separation for alpha-amylase and lipase, while celullase and peroxidase precipitated with some activity reduction. Analysis of similar experiments with ammonium and sodium sulfate did not affect the activity of enzymes. CONCLUSION: Celullase and peroxidase were denatured by ammonium carbamate. While more systematic studies are not available, care must be taken in designing a protein precipitation with this salt. The results suggest that the generally accepted idea that salts that denature proteins tend to solubilize them does not hold for ammonium carbamate. (C) 2010 Society of Chemical Industry

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Minimal pasteurization of orange juice (OJ) consists of using minimum holding time and temperature to ensure partial inactivation of pectin methylesterase (PME). This process produces juice with preserved sensory attributes and has a better acceptance by consumers when compared with commercially pasteurized OJ. Sensory profile and physical-chemical characteristics of minimally processed OJ was determined, during refrigerated storage, for two OJ blends with different pH values and the same level of PME thermal inactivation. A selected and trained sensorial panel (n = 16) performed sensory analysis, based on a quantitative descriptive analysis, twice a week for 30 days, evaluating the attributes of appearance (suspended particles and color intensity), odor (natural orange and fermented orange) and flavor (orange characteristic, fermented orange, acid and bitter taste). Storage presented great effect on OJ sensory profile; however, it was not noticeable on physical-chemical characteristics.

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For the optimal design of plate heat exchangers (PHEs), an accurate thermal-hydraulic model that takes into account the effect of the flow arrangement on the heat load and pressure drop is necessary. In the present study, the effect of the flow arrangement on the pressure drop of a PHE is investigated. Thirty two different arrangements were experimentally tested using a laboratory scale PHE with flat plates. The experimental data was used for (a) determination of an empirical correlation for the effect of the number of passes and number of flow channels per pass on the pressure drop; (b) validation of a friction factor model through parameter estimation; and (c) comparison with the simulation results obtained with a CFD (computational fluid dynamics) model of the PHE. All three approaches resulted in a good agreement between experimental and predicted values of pressure drop. Moreover, the CFD model is used for evaluating the flow maldistribution in a PHE with two channels Per Pass. (c) 2008 Elsevier Ltd. All rights reserved.

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The sugarcane spittlebug, Mahanarva fimbriolata (Hemiptera: Cercopidae), is considered the most important pest of sugarcane harvested without the burning of trash, or green cane, in Brazil. The objective of this work was to compare the biology of M. fimbriolata on six sugarcane varieties: SP79-1011, SP80-1816, SP80-1842, SP81-3250, RB72454, and RB835486. The experiments were conducted at a temperature of 25 +/- 1 degrees C, RH of 70 +/- 10%, and a photoperiod of 14:10 [L:D]. Variety RB72454 outperformed the rest, reducing the nymphal population that fed on its roots by 50%. With regard to adults, variety SP81-3250 allowed greater mean longevity of males (38 days) and females (51 days), greater mean oviposition period (46 days), and higher mean fecundity (1215 eggs/female); these parameters were statistically different from those obtained with other varieties. For the eggs, there was no significant effect of variety on developmental time or viability. Consequently, the variety SP81-3250 should be avoided in areas predisposed to the occurrence of M. fimbriolata.