RESUMO
Chemical kinetics models for ethanol under ultra-lean engine conditions were evaluated to couple with CFD multidimensional simulations of a spark-assisted homogeneous charge compression ignition (HCCI) rotary engine. Five reduced reaction sets proper for CFD simulations and two detailed reaction mechanisms for comparison were tested by simulating ignition delay times, laminar flame speeds, and a single-cycle HCCI engine with virtual piston dimensions. The simulated results of the new mechanism with 188 reactions were well-fitted to both experimental ignition delay times for ultra-lean ethanol/air conditions and laminar flame speeds at high pressures. This reaction set resulted in better-simulated ignition delay times at 30 and 40 bar for ultra-lean ethanol/air conditions than other chemical kinetics models. Maximum temperatures and pressures of 2500-2580 K and 280-289 bar, respectively, were observed for hydrous ethanol/air under ultra-lean conditions in HCCI engine. In addition, the simulation results of the HCCI ethanol engine presented high pressure rise rates of 8-26 bar/CAD at 3600 rpm. These results indicated that the engine test should be carried out at 2500 rpm with 2 bar of boost pressure for CFD model calibration with the new optimized reaction mechanism.
RESUMO
The hospital anxiety depression scale (HADS) is a benchmark used to investigate possible and probable cases of psychosomatic illness. Its affiliation with autonomic recovery after exercise is unclear and, as a technique applied to evaluate cardiovascular risk. We assessed a possible link between HADS and autonomic recovery after exercise. We studied healthy subjects split into two groups: Low HADS (n = 20) and High HADS (n = 21). Subjects consented to moderate aerobic exercise on a treadmill at 60% to 65% of the maximum heart rate (HR) for 30 min. We studied HR variability (HRV) before and during 30 min after exercise. Subjects with higher HADS values presented delayed recovery of HR and root-mean square of differences between adjacent normal RR intervals (RMSSD) after submaximal exercise. RMSSD during recovery from exercise had a significant association with HADS. In summary, subjects with higher HADS presented slower vagal recovery following exercise.
Assuntos
Ansiedade , Depressão , Exercício Físico , Frequência Cardíaca , Adulto , Sistema Nervoso Autônomo/fisiologia , Exercício Físico/fisiologia , Teste de Esforço , Feminino , Frequência Cardíaca/fisiologia , Hospitais , Humanos , Masculino , Técnicas ProjetivasRESUMO
Polyphosphates (polyPs) have been found in all cell types examined to date and play diverse roles, depending on the cell type. In eukaryotic organisms, polyPs have been mainly investigated in mammalian cells, with few studies on insects. In this study, we investigated mitochondrial polyphosphate metabolism in the red flour beetle, Tribolium castaneum. Substrate specificity for different chain lengths demonstrated the presence of two exopolyphosphatase isoforms in mitochondria. T. castaneum mitochondrial polyP levels decreased after injection with soluble pyrophosphatase (Tc-sPPase) dsRNA, while the membrane exopolyphosphate activity increased. Mitochondrial respiration modulated exopolyphosphatase activity only in wild-type beetles. Tripolyphosphate was able to increase the F-ATPase activity in wild-type and Tc-sPPase RNAi beetles. We suggest that inorganic pyrophosphatase modulates polyphosphate metabolism in mitochondria and affects the link between mitochondrial activity and polyphosphate metabolism in T. castaneum.
Assuntos
Pirofosfatase Inorgânica/metabolismo , Mitocôndrias/metabolismo , Polifosfatos/metabolismo , Tribolium/enzimologia , Adenosina Trifosfatases , Animais , Feminino , Pirofosfatase Inorgânica/química , Proteínas de Insetos/metabolismo , Masculino , Interferência de RNA , Tribolium/metabolismoRESUMO
The production of vegetable crops has been characterized as a highly intensive activity in the use of soil, water, inputs and labor in semi-arid regions, being practiced mostly by small family farmers as a way of subsistence, or in the small-scale commercialization of surplus production. Among the agricultural practices that have been successfully used by vegetable producers are intercrop systems that, when implemented with adequate management, present gains in productivity, nutritional, economic, and environmental value. The aim of this study was to estimate the optimal plot sizes of plantings of carrot (Daucus carota L.) intercropped with arugula (Eruca sativa L.) in bi-cultivation in three spatial arrangements, as well as to determine bio-agroeconomic revenues from associations between these vegetable crops in a semi-arid region. Estimates of optimal sizes of experimental plots in intercropping systems, provided by the methods of bootstrap resampling and of sampling intensity (10%), were four, four and three basic units, respectively, for the spatial arrangements 2R:2C, 3R:3C, and 4R: 4C, between rows of arugula (R) intercropped with carrot (C), and by the Hatheway method, all spatial arrangements were of four basic units. The best bio-agroeconomic performance of carrot intercropped with arugula in bi-cultivation was obtained in the spatial arrangement 2R:2C.