39 resultados para combined heat and power production

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)


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Introduction: Fibroblasts are the most abundant cells in dental pulp. To investigate their capacity to produce the chemokines CCL3, CXCL8, and CXCL12 as well as nitric oxide (NO), we evaluated the production of these mediators in supernatants of cultured human dental pulp fibroblasts (HDPF) stimulated by heat-killed Enterococcus faecalis (HKEF). Methods: Primary cultures of HDPF were stimulated with medium alone or HKEF (1:1, 10:1, or 100:1 bacteria:fibroblast) for 1, 6, and 24 hours. Chemokines and NO were assessed through enzyme-linked immunosorbent assay and Griess reaction, respectively. Statistical analysis was performed by using analysis of variance and Tukey post test. Results: CCL3 was not detected, whereas constitutive CXCL8 was not affected. Production of CXCL12 was increased at 1 and 6 hours, and NO was increased at the concentration of 1:1 bacteria:fibroblast at 24 hours. Viability and proliferation assays did not reveal cell number differences. Conclusions: These findings demonstrate that heat-killed E. faecalis is able to increase production of CXCL12 and NO by HDPF. (J Endod 2010;36:91-94)

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Transplantation of pancreatic islets is efficient in improving the metabolic control and quality of life and in preventing severe hypoglycemia in patients with brittle type I diabetes mellitus. More accurate methods to assess islet viability would be extremely useful in designing target interventions for islet cytoprorection and in reducing the number of islets required to achieve insulin independence. Here we report on an application of calorimetry to evaluate the metabolic response of pancreatic islets to glucose stimulation. A significant increase in metabolic heat was produced by islet samples when consecutively subjected to 2.8 and 16.3 mmol L-1 glucose. Under these glucose concentrations, 1000 islets released average heat values of 9.16 +/- 0.71 mJ and 14.90 +/- 1.21 mJ over 50 min, respectively. Additionally, the glucose stimulation indexes were 1.67 +/- 0.30 for insulin. 1.72 +/- 0.13 for heat and 2.91 +/- 0.50 for lactate, raising the important possibility of substituting the secreted insulin index/ratio by the index/ratio of the heat released in the evaluation of Langerhans islets viability for transplantation. Altogether, Our results demonstrate the applicability of calorimetry to assess the quality of isolated pancreatic islets and to study vital islet functions. (c) 2008 Published by Elsevier B.V.

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The biological cause of Pork Stress syndrome, which leads to PSE (pale, soft, exudative) meat, is excessive release of Ca(2+) ions, which is promoted by a genetic mutation in the ryanodine receptors (RyR) located in the sarcoplasmic reticulum of the skeletal muscle cells. We examined the relationship between the formation of PSE meat under halothane treatment and heat stress exposure in chicken alpha RYR hot spot fragments. Four test groups were compared: 1) birds slaughtered without any treatment, i.e., the control group (C); 2) birds slaughtered immediately after halothane treatment (H); 3) birds slaughtered immediately after heat stress treatment (HS), and 4) birds exposed to halothane and to heat stress (H+HS), before slaughtering. Breast muscle mRNA was extracted, amplified by RT-PCR, and sequenced. PSE meat was evaluated using color determination (L*value). The most common alteration was deletion of a single nucleotide, which generated a premature stop codon, resulting in the production of truncated proteins. The highest incidence of nonsense transcripts came with exposure to halothane; 80% of these abnormal transcripts were detected in H and H+HS groups. As a consequence, the incidence of abnormal meat was highest in the H+HS group (66%). In HS, H, and C groups, PSE meat developed in 60, 50, and 33% of the samples, respectively. Thus, halothane apparently modulates alpha RYR gene expression in this region, and synergically with exposure to heat stress, causes Avian Stress syndrome, resulting in PSE meat in broiler chickens.

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In order to verify the effects of heat and exercise acclimation (HA) on resting and exercise-induced expression of plasma and leukocyte heat shock protein 72 (Hsp72) in humans, nine healthy young male volunteers (25.0 +/- 0.7 years; 80.5 +/- 2.0 kg; 180 +/- 2 cm, mean +/- SE) exercised for 60 min in a hot, dry environment (40 +/- 0A degrees C and 45 A +/- 0% relative humidity) for 11 days. The protocol consisted of running on a treadmill using a controlled hyperthermia technique in which the work rate was adjusted to elevate the rectal temperature by 1A degrees C in 30 min and maintain it elevated for another 30 min. Before and after the HA, the volunteers performed a heat stress test (HST) at 50% of their individual maximal power output for 90 min in the same environment. Blood was drawn before (REST), immediately after (POST) and 1 h after (1 h POST) HST, and plasma and leukocytes were separated and stored. Subjects showed expected adaptations to HA: reduced exercise rectal and mean skin temperatures and heart rate, and augmented sweat rate and exercise tolerance. In HST1, plasma Hsp72 increased from REST to POST and then returned to resting values 1 h POST (REST: 1.11 A +/- 0.07, POST: 1.48 A +/- 0.10, 1 h POST: 1.22 A +/- 0.11 ng mL(-1); p < 0.05). In HST2, there was no change in plasma Hsp72 (REST: 0.94 A +/- 0.08, POST: 1.20 A +/- 0.15, 1 h POST: 1.17 A +/- 0.16 ng mL(-1); p > 0.05). HA increased resting levels of intracellular Hsp72 (HST1: 1 A +/- 0.02 and HST2: 4.2 A +/- 1.2 density units, p < 0.05). Exercise-induced increased intracellular Hsp72 expression was observed on HST1 (HST1: REST, 1 A +/- 0.02 vs. POST, 2.9 A +/- 0.9 density units, mean +/- SE, p < 0.05) but was inhibited on HST2 (HST2: REST, 4.2 +/- 1.2 vs. POST, 4.4 +/- 1.1 density units, p > 0.05). Regression analysis showed that the lower the pre-exercise expression of intracellular Hsp72, the higher the exercise-induced increase (R = -0.85, p < 0.05). In conclusion, HA increased resting leukocyte Hsp72 levels and inhibited exercise-induced expression. This intracellular adaptation probably induces thermotolerance. In addition, the non-increase in plasma Hsp72 after HA may be related to lower stress at the cellular level in the acclimated individuals.

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The structure of probability currents is studied for the dynamical network after consecutive contraction on two-state, nonequilibrium lattice systems. This procedure allows us to investigate the transition rates between configurations on small clusters and highlights some relevant effects of lattice symmetries on the elementary transitions that are responsible for entropy production. A method is suggested to estimate the entropy production for different levels of approximations (cluster sizes) as demonstrated in the two-dimensional contact process with mutation.

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Oxides RNiO(3) (R - rare-earth, R not equal La) exhibit a metal-insulator (MI) transition at a temperature T(MI) and an antiferromagnetic (AF) transition at T(N). Specific heat (C(P)) and anelastic spectroscopy measurements were performed in samples of Nd(1-x)Eu(x)NiO(3), 0 <= x <= 0.35. For x - 0, a peak in C(P) is observed upon cooling and warming at essentially the same temperature T(MI) - T(N) similar to 195 K, although the cooling peak is much smaller. For x >= 0.25, differences between the cooling and warming curves are negligible, and two well defined peaks are clearly observed: one at lower temperatures that define T(N), and the other one at T(MI). An external magnetic field of 9 T had no significant effect on these results. The elastic compliance (s) and the reciprocal of the mechanical quality factor (Q(-1)) of NdNiO(3), measured upon warming, showed a very sharp peak at essentially the same temperature obtained from C(P), and no peak is observed upon cooling. The elastic modulus hardens below T(MI) much more sharply upon warming, while the cooling and warming curves are reproducible above T(MI). Conversely, for the sample with x - 0.35, s and Q(-1) curves are very similar upon warming and cooling. The results presented here give credence to the proposition that the MI phase transition changes from first to second order with increasing Eu doping. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3549615]

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The STAR Collaboration at the Relativistic Heavy Ion Collider presents a systematic study of high-transverse-momentum charged-di-hadron correlations at small azimuthal pair separation Delta phi in d+Au and central Au+Au collisions at s(NN)=200 GeV. Significant correlated yield for pairs with large longitudinal separation Delta eta is observed in central Au+Au collisions, in contrast to d+Au collisions. The associated yield distribution in Delta eta x Delta phi can be decomposed into a narrow jet-like peak at small angular separation which has a similar shape to that found in d+Au collisions, and a component that is narrow in Delta phi and depends only weakly on Delta eta, the ""ridge."" Using two systematically independent determinations of the background normalization and shape, finite ridge yield is found to persist for trigger p(t)>6 GeV/c, indicating that it is correlated with jet production. The transverse-momentum spectrum of hadrons comprising the ridge is found to be similar to that of bulk particle production in the measured range (2 < p(t)< 4 GeV/c).

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Blanks (flasks without substrate containing only inoculum and medium) are used in vitro to correct for gas. CH(4) and residual organic matter (OM) fermented in inoculum. However inclusion of rumen fermentation modifiers may affect fermentation of OM in the substrate and inoculum. Thus, data correction using blanks that lack additives may result in inaccurate adjustment for background fermentation. Our objective was to evaluate impacts of using blanks containing additive (i.e., specific blanks) or blanks without additive on estimation of in vitro net gas and CH(4) production. We used the semi-automatic in vitro gas production technique including monensin sodium at 2.08 mg/l of buffered rumen fluid (Experiment 1) or carvacrol, eugenol and 1,8-cineol at 667 mg/l (Experiment 2) in flasks with substrate and in blank flasks. At 16h of incubation, monensin reduced (P <= 0.02) total gas production in flasks containing substrate (162.0 ml versus 146.3 ml) and in blanks (84.4 ml versus 79.2 ml). Total methane production was also decreased (P <= 0.05) by adding monensin to flasks containing substrate (15.7 ml versus 11.9 ml) as well as in blanks (6.4 ml versus 5.0 ml). Inclusion of carvacrol or eugenol reduced (P <= 0.05) total gas and CH(4) production in flasks with substrate and in blanks, but in a more pronounced manner than monensin. For these three additives, correction for blank without additive resulted in lower net gas and CH(4) production than correction for a treatment specific blank. For instance, correcting carvacrol data using a blank without the additive resulted in negative net gas and CH(4) production (-6.5 and -1.5 ml. respectively). These biologically impossible results occurred because total gas and CH(4) production in blanks without carvacrol (46.1 and 2.1 ml, respectively) were higher than in flasks containing substrate plus carvacrol (39.7 and 0.6 ml, respectively). Results demonstrated that inclusion of rumen additives affected fermentation of OM in the substrate and the inoculum. Thus, correction of gas and CH(4) production using blanks without additives resulted in overestimation of these variables. Blanks containing the additive of interest should be included when rumen fermentation modifiers are evaluated in vitro. This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson. (C) 2011 Elsevier B.V. All rights reserved.

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Tomato is amongst the most consumed vegetables in the world, not only for its culinary versatility but also for its high nutritional value. In the last years, consumers have shown an increased concern regarding food origin and safety. The organic tomato production has been a promising alternative for the consumer offering a safer food in relation to environmental, social and nutritional aspects. This study assessed the chemical composition of tomato seeds produced in both conventional and organic systems by INAA. The results showed significant differences (P <= 0.05) in the mass fractions of Br, Cs, Eu, Fe, K, Mo, Na, Rb and Sm between both systems, indicating influence of the crop management adopted in the different tomato production systems.

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The purpose of our study was to compare the effects of 8-week progressive strength and power training regimens on strength gains and muscle plasticity [muscle fiber hypertrophy and phenotype shift, mammalian target of rapamycin (mTOR), regulatory-associated protein of mTOR (RAPTOR), rapamycin-insensitive companion of m-TOR (RICTOR), calcineurin and calcipressin gene expression]. Twenty-nine physically active subjects were divided into three groups: strength training (ST), power training (PT) and control (C). Squat 1 RM and muscle biopsies were obtained before and after the training period. Strength increased similarly for both ST and PT groups (P < 0.001). Fiber types I, IIa and IIb presented hypertrophy main time effect (P < 0.05). Only type IIb percentage decreased from pre- to post-test (main time effect, P < 0.05). mTOR and RICTOR mRNA expression increased similarly from pre- to post-test (P < 0.01). RAPTOR increased after training for both groups (P < 0.0001), but to a greater extent in the ST (P < 0.001) than in the PT group. 4EBP-1 decreased after training when the ST and PT groups were pooled (P < 0.05). Calcineurin levels did not change after training, while calcipressin increased similarly from pre- to post-test (P < 0.01). In conclusion, our data indicate that these training regimens produce similar performance improvements; however, there was a trend toward greater hypertrophy-related gene expression and muscle fiber hypertrophy in the ST group.

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Ide, BN, Leme, TCF, Lopes, CR, Moreira, A, Dechechi, CJ, Sarraipa, MF, da Mota, GR, Brenzikofer, R, and Macedo, DV. Time course of strength and power recovery after resistance training with different movement velocities. J Strength Cond Res 25(7): 2025-2033, 2011-The purpose of this study was to evaluate the time course of strength and power recovery after a single bout of strength training designed with fast and slow contraction velocities. Nineteen male subjects were randomly divided into 2 groups: the slow-velocity contraction (SV) group and the fast velocity contraction (FV) group. Resistance training protocols consisted of 5 sets of 12 repetition maximum (5 x 12RM) with 50 seconds of rest between sets and 2 minutes between exercises. Contraction velocity was controlled by the execution time for each repetition (SV-6 seconds to complete concentric and eccentric phases and for FV-1.5 seconds). Leg Press 45 degrees 1RM (LP 1RM), horizontal countermovement jump (HCMJ), and right thigh circumference (TC) were accessed in 6 distinct moments: base (1 week before exercise), 0 (immediately after exercises), 24, 48, 72, and 96 hours after exercise protocol. The SV and FV presented significant LP 1RM decrements at 0, and these were still evident 24-48 hours postexercise. The magnitude of decline was significantly (p<0.05) higher for FV. The SV and FV presented significant HCMJ decrements at 0, but only for FV were these still evident 24-72 hours postexercise. The SV and FV presented significant TC increments at 0, and these were still evident 24-48 hours postexercise for SV but for FV it continued up to 96 hours. The magnitude of increase was significantly (p<0.05) higher for FV. In conclusion, the fast contraction velocity protocol resulted in greater decreases in LP 1RM and HCMJ performance, when compared with slow velocity. The results lead us to interpret that this variable may exert direct influence on acute muscle strength and power generation capacity.

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BACKGROUND: Xylitol is a sugar alcohol (polyalcohol) with many interesting properties for pharmaceutical and food products. It is currently produced by a chemical process, which has some disadvantages such as high energy requirement. Therefore microbiological production of xylitol has been studied as an alternative, but its viability is dependent on optimisation of the fermentation variables. Among these, aeration is fundamental, because xylitol is produced only under adequate oxygen availability. In most experiments with xylitol-producing yeasts, low oxygen transfer volumetric coefficient (K(L)a) values are used to maintain microaerobic conditions. However, in the present study the use of relatively high K(L)a values resulted in high xylitol production. The effect of aeration was also evaluated via the profiles of xylose reductase (XR) and xylitol clehydrogenase (XD) activities during the experiments. RESULTS: The highest XR specific activity (1.45 +/- 0.21 U mg(protein)(-1)) was achieved during the experiment with the lowest K(L)a value (12 h(-1)), while the highest XD specific activity (0.19 +/- 0.03 U mg(protein)(-1)) was observed with a K(L)a value of 25 h(-1). Xylitol production was enhanced when K(L)a was increased from 12 to 50 h(-1), which resulted in the best condition observed, corresponding to a xylitol volumetric productivity of 1.50 +/- 0.08 g(xylitol) L(-1) h(-1) and an efficiency of 71 +/- 6.0%. CONCLUSION: The results showed that the enzyme activities during xylitol bioproduction depend greatly on the initial KLa value (oxygen availability). This finding supplies important information for further studies in molecular biology and genetic engineering aimed at improving xylitol bioproduction. (C) 2008 Society of Chemical Industry

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The objective of this work was to characterize the delignification effluent originating from the delignification industry and evaluate the combination of the fungus and photocatalytic process (TiO(2)/UV system) for the treatment of this effluent. The delignification effluent has proven harmful to the environment because it presents high color (3516 CU), total phenol (876 mg/L and TOC (1599 mg/L) and is also highly toxic even in a low concentration. The results of photocatalysis were 11%, 25% and 13% higher for reductions in color, total phenol and TOC, respectively. The combined treatments presented benefits when compared to the non-combined treatments. Fungus and photocatalysis in combination proved to be the best treatment, reducing the color, total phenol, toxicity (inhibition of Escherichia coli growth) and TOC by 94.2%, 92.6%, 4.9% and 62%, respectively. (C) 2008 Elsevier B.V. All rights reserved.

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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 flow type and rotor speed was investigated in a round-bottom reactor with 5 L useful volume containing 2.0 L of granular biomass. The reactor treated 2.0 L of synthetic wastewater with a concentration of 800 mgCOD/L in 8-h cycles at 30 degrees C. Five impellers, commonly used in biological processes, have been employed to this end, namely: a turbine and a paddle impeller with six-vertical-flat-blades, a turbine and a paddle impeller with six-45 degrees-inclined-flat-blades and a three-blade-helix impeller. Results showed that altering impeller type and rotor speed did not significantly affect system stability and performance. Average organic matter removal efficiency was about 84% for filtered samples, total volatile acids concentration was below 20 mgHAc/L and bicarbonate alkalinity a little less than 400 mgCaCO(3)/L for most of the investigated conditions. However, analysis of the first-order kinetic model constants showed that alteration in rotor speed resulted in an increase in the values of the kinetic constants (for instance, from 0.57 h(-1) at 50 rpm to 0.84 h(-1) at 75 rpm when the paddle impeller with six-45 degrees-inclined-flat-blades was used) and that axial flow in mechanically stirred reactors is preferable over radial-flow when the vertical-flat-blade impeller is compared to the inclined-flat-blade impeller (for instance at 75 rpm, from 0.52 h(-1) with the six-flat-blade-paddle impeller to 0.84 h(-1) with the six-45 degrees-inclined-flat-blade-paddle impeller), demonstrating that there is a rotor speed and an impeller type that maximize solid-liquid mass transfer in the reaction medium. Furthermore, power consumption studies in this reduced reactor volume showed that no high power transfer is required to improve mass transfer (less than 0.6 kW/10(3) m(3)). (C) 2008 Elsevier Ltd. All rights reserved.