510 research outputs found

    Anaerobic digestion of OMW : intermittent feeding strategy and LCFA oxidation profile

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    ManuscriptAn intermittent feeding strategy was applied to the anaerobic treatment of raw olive mill wastewater (OMW). Two reactors were operated under influent concentrations of 5 to 50 g COD L-1. Two and one batch (feed-less) periods were applied to reactor R1 and R2, respectively, operating in continuous thenceforth. It was demonstrated that the intermittent feeding of OMW improved the mineralization of accumulated Long Chain Fatty Acids (LCFA) inside the reactor. Nevertheless, LCFA accumulated again when the organic loading rate was increased from 2 to 3 and 5 kg COD m-3 d-1. The profiles of LCFA, obtained with OMW digestion, were different from previous studies with synthetic effluents. At the beginning of reactors operation, oleate was the main LCFA compound (~50%) followed by palmitate. Afterwards, a shift in the LCFA pattern accumulation was noticed for both reactors. At periods with higher OMW concentrations (30-50 g COD L-1, 3-5 kg COD m-3 d-1) palmitate was the main LCFA accumulated with 69% at R1 and 54% at R2. For real oily wastewaters, a periodically batch period could be a practical solution to maintain low values of LCFA inside the reactor. The addition of a nitrogen source was essential to enhance the methane yield

    Somatotype is more interactive with strength than fat mass and physical activity in peripubertal children

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    The purpose of this study was to analyse the interaction between somatotype, body fat and physical activity in prepubescent children. This was a cross!sectional study design involving 312 children (160 girls, 152 boys) aged between 10 and 11.5 years old (10.8 ± 0.4 years old). Evaluation of body composition was done determining body mass index and body fat by means of skin!fold measurements, using the method described by Slaughter. Somatotype was computed according to the Carter’s method. Physical activity was assessed with the Baecke questionnaire. The physical activity assessment employed sets of curl!ups, push!ups, standing broad jump, medicine ball throw, handgrip strength and Margaria!Kalamen power stair. There were negative associations for body fat, endomorphy and mesomorphy with curl!ups, push!ups and broad jump tests and positive associations with ball throw, handgrip strength and Margaria! Kalamen power tests. The associations for ectomorphy were the inverse of those for endomorphy and mesomorphy. Non obese children presented higher values for curl!ups, push!ups and standing broad jump. In medicine ball throw, handgrip strength and Margaria!Kalamen power test obese children presented higher scores, followed by children who were overweight. The mesoectomorphic boys and ectomesomorphic girls performed higher in all tests. The morphological typology presented more interactions with strength than % of body fat and physical activity. These data seem to suggest that the presence/absence of certain physical characteristics is crucial in the levels of motor provision in prepubescent children

    Unravelling the effect of strand orientation on exciton migration in conjugated polymers

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    The study of the average distance that singlet excitons travel during their lifetime in conjugated polymers has attracted considerable attention during the past decade, because of its importance in the functioning of many polymer-based optoelectronic devices, like solar cells and photodetectors. Intriguingly, different values of exciton diffusion length have been extracted from experiments on seemingly identical conjugated polymers. Here we use computer simulations to show that the observed discrepancies in the reported values of the exciton diffusion length may arise from differences in the orientation of conjugated polymer strands relative to the substrate surface, a factor which has been mostly overlooked. Our results show that, on pristine polymer nanodomains with conjugated strands perpendicular to the substrate surface, exciton migration length is approximately 30% and 40% lower than on those with parallel and random strand orientation relative to that surface, respectively, resulting from the different contents of physical traps present in nanodomains with different strand orientation. This work underlines the importance of molecular arrangement on exciton migration, and provides a novel theoretical framework for estimating the dependence of the exciton diffusion length with the orientation of conjugated polymers strands within the nanodomains, as well as helping the design of more efficient polymer-based optical and optoelectronic devices, such as optical sensors, photodiodes, photovoltaic cells and white light-emitting diodes.This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2011, and under the projects CONC-REEQ/443/EEI/2005 and PEst-C-FIS/UI607/2011-2012. Two of us (H.M.G.C. and H. M. C. B.) are also indebted to FCT and POPH for financial support the post-doctoral grants SFRH/BPD/64554/2009 and SFRH/BPD/80561/2011

    Ab initio study of the properties of Ti1-x-ySixAlyN solid solution

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    We have studied the electronic, structural, and elastic properties of Ti1-x-ySixAlyN metastable phase, using first principles calculations based on the density functional theory. These calculations provide the lattice parameter, density of states, cohesive energy, formation energy and elastic constants, when Si and Al atoms replace Ti in the TiN lattice. The calculated values of lattice parameters and elastic constants are generally in good agreement with experiments and compare well with other theoretical results. We show that the trend followed by cohesive energy, formation energy, elastic constants is related to the electronic properties and bonding characteristics of these compounds

    Adhesion of bis-salphen-based coordination polymers to graphene: insights from free energy perturbation study

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    Manipulation of nanoscale objects using molecular self-assembly is a potent tool to achieve large scale nanopatterning with small effort. Coordination polymers of bis-salphen compounds based on zinc have demonstrated their ability to align carbon nanotubes into micro-scale networks with an unusual “rings-and-rods” pattern. This paper investigates how the compounds interact with pristine and functionalized graphene using density functional theory calculations and molecular dynamic simulations. Using the free energy perturbation method we will show how the addition of phenyl side groups to the core compound and functionalization of graphene affect the stability, mobility and conformation adopted by a dimer of bis-(Zn)salphen compound adsorbed on graphene surface and what it can reveal about the arrangement of chains of bis-(Zn)salphen polymer around carbon nanotubes during the self-assembly of microscale networks.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020 and projects SATRAP (POCI-01-442 0145-FEDER-028108) and SATRAP-PLUS (EXPL/FIS-MAC/0947/2021)

    Effects of Concurrent Training on Explosive Strength and VO2max in Prepubescent Children

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    The purpose of this study was to compare the effects of an 8-weeks training period of resistance training alone (GR), combined resistance and endurance training (GCON) and a control group (GC) on explosive strength and V(O2max) in a large sample of prepubescent boys and girls. 125 healthy children (58 boys, 67 girls), aged 10-11 years old (10.8±0.4 years) were assigned into 2 training groups to train twice a week for 8 weeks: GR (19 boys, 22 girls), GCON (21 boys, 24 girls) and a control group (GC: 18 boys, 21 girls; no training program). A significant but medium-sized increase from pre- to the post-training in the vertical jump (Effect size=0.22, F=34.44, p<0.01) and V(O2max) (Effect size=0.19, F=32.89, p<0.01) was observed. A significant large increase in the 1 kg (Effect size=0.53, F=202.17, p<0.01) and 3 kg (Effect size=0.48, F=132.1, p<0.01) ball throwing, standing long jump (Effect size=0.53, F=72.93, p<0.01) and running speed (Effect size=0.45, F=122.21, p<0.01) was also observed. The training group (GR and GCON) and sex factors did not significantly influence the evolution of strength variables from pre- to the post-training. The V(O2max) increased significantly only in GCON. Concurrent training is equally effective on training-induced explosive strength, and more efficient than resistance training only for V(O2max), in prepubescent boys and girls. This should be taken into consideration in order to optimize strength training school-based programs.info:eu-repo/semantics/publishedVersio

    Validity and Reliability of the Portuguese Version of the Dispositional Flow Scale-2 in Exercise

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    This study aimed to analyze the factorial validity and reliability of the Portuguese version of the Dispositional Flow Scale-2 (DFS-2; Jackson and Eklund, 2002) with a sample of 1437 exercise participants, a population in which flow has not been widely studied. The CFA adjustment indices of the nine-factor first-order structure were acceptable. Both the time transformation and loss of self-consciousness scales presented modest correlations with the remaining flow dimensions. Internal consistency estimates were satisfactory for all flow factors. Except for time transformation, all the dispositional flow scales correlated with perceived competence in and enjoyment of exercise. These findings provide support for the validity and reliability of the Portuguese version of the DFS-2 for measuring flow experiences in exercise. The use of the nine flow factor level scores rather than a single global score is recommended

    Classification of Techniques Used in Self-Determination Theory-Based Interventions in Health Contexts: An Expert Consensus Study

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    While evidence suggests that interventions based on self-determination theory can be effective in motivating adoption and maintenance of health-related behaviors, and in promoting adaptive psychological outcomes, the motivational techniques that comprise the content of these interventions have not been comprehensively identified or described. The aim of the present study was to develop a classification system of the techniques that comprise self-determination theory interventions, with satisfaction of psychological needs as an organizing principle. Candidate techniques were identified through a comprehensive review of self-determination theory interventions and nomination by experts. The study team developed a preliminary list of candidate techniques accompanied by labels, definitions, and function descriptions of each. Each technique was aligned with the most closely-related psychological need satisfaction construct (autonomy, competence, or relatedness). Using an iterative expert consensus procedure, participating experts (N=18) judged each technique on the preliminary list for redundancy, essentiality, uniqueness, and the proposed link between the technique and basic psychological need. The procedure produced a final classification of 21 motivation and behavior change techniques (MBCTs). Redundancies between final MBCTs against techniques from existing behavior change technique taxonomies were also checked. The classification system is the first formal attempt to systematize self-determination theory intervention techniques. The classification is expected to enhance consistency in descriptions of self-determination theory-based interventions in health contexts, and assist in facilitating synthesis of evidence on interventions based on the theory. The classification is also expected to guide future efforts to identify, describe, and classify the techniques that comprise self-determination theory-based interventions in multiple domains.</p

    Effects of body fat and dominant somatotype on explosive strength and aerobic capacity trainability in prepubescent children

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    he purpose of this study was to analyze the influence of body fat and somatotype on explosive strength and aerobic capacity trainability in the prepubertal growth spurt, marked by rapid changes in body size, shape, and composition, all of which are sexually dimorphic. One hundred twenty-five healthy children (58 boys, 67 girls), aged 10–11 years (10.8 6 0.4 years), who were self-assessed in Tanner stages 1–2, were randomly assigned into 2 experimental groups to train twice a week for 8 weeks: strength training group (19 boys, 22 girls), endurance training group (21 boys, 24 girls), and a control group (18 boys, 21 girls). Evaluation of body fat was carried out using the method described by Slaughter. Somatotype was computed according to the Heath-Carter method. Increased endomorphy reduced the likelihood of vertical jump height improvement (odds ratio [OR], 0.10; 95% confidence interval [CI], 0.01–0.85), increased mesomorphy (OR, 6.15; 95% CI, 1.52–24.88) and ectomorphy (OR, 6.52; 95% CI, 1.71–24.91) increased the likelihood of sprint performance, and increased ectomorphy (OR, 3.84; 95% CI, 1.20–12.27) increased the likelihood of aerobic fitness gains. Sex did not affect the training-induced changes in strength or aerobic fitness. These data suggest that somatotype has an effect on explosive strength and aerobic capacity trainability, which should not be disregarded. The effect of adiposity on explosive strength, musculoskeletal magnitude on running speed, and relative linearity on running speed and aerobic capacity seem to be crucial factors related to training-induced gains in prepubescent boys and girls.info:eu-repo/semantics/publishedVersio
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