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

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

Strategies for lipids and phenolics degradation in the anaerobic treatment of olive mill wastewater

Strategies are proposed for the anaerobic treatment of lipid and phenolic-rich effluents, specifically the raw olive mill wastewater (OMW). Two reactors were operated under OMW influent concentrations from 5 to 48 g COD L-1 and Hydraulic Retention Time between 10 and 5 days. An intermittent feeding was applied whenever the reactors showed a severe decay in the methane yield. This strategy improved the mineralization of oleate and palmitate, which were the main accumulated Long Chain Fatty Acids (LCFA), and also promoted the removal of resilient phenolic compounds, reaching remarkable removal efficiencies of 60% and 81% for two parallel reactors at the end of a feed-less period. A maximum biogas production of 1.4 m3 m-3 d-1 at an Organic Loading Rate of 4.8 kg COD m-3 d-1 was obtained. Patterns of individual LCFA oxidation during the OMW anaerobic digestion are presented and discussed for the first time. The supplementation of a nitrogen source boosted immediately the methane yield from 21 and 18 to 76 and 93% in both reactors. The typical problems of sludge flotation and washout during the anaerobic treatment of this oily wastewater were overcome by biomass retention, according to the Inverted Anaerobic Sludge Blanket (IASB) reactor concepts. This work demonstrates that it is possible to avoid a previous detoxification step by implementing adequate operational strategies to the anaerobic treatment of OMW.The authors acknowledge the financial support of the “Fundação para a Ciência e a Tecnologia”, FCT/MCTES, through the project PTDC/ENR/69755/2006 and also through the grants given to Marta Gonçalves SFRH/BD/40746/2007 and José Carlos Costa SFRH/BDP/ 48962 /2008. The authors thank Tânia Ferreira for the help in LCFA analysis and Ana Cavaleiro for her scientific support

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

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

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

Influence of electrode degradation on organic solar cells functioning – a computational study

Recently, organic solar cells (OSC) have reached the efficiency of 10% becoming a reliable alternative to the conventional high cost inorganic solar cells. However, to gain a place in the competitive market of solar cells it is necessary to improve their lifetime. Due to the nature of the materials used, there are several degradation mechanisms [1] that lead to a decrease on device efficiency and thus to its failure, being of upmost importance to understand how they affect organic solar cells functioning. One of these mechanisms consists on electrodes degradation when in contact with air or water, leading to a change on electrode work function and thus of the energy levels at electrode/organic layer interface. As a result, the decrease on OSC efficiency has been attributed to a loss on the electrode´s ability in collecting charges from the active layer [2, 3]. However, it is unclear how a change on electrode’s work function affects the main optoelectronic mechanisms that rule the device performance [4], which can give some guidelines to prevent its failure. In order to clarify this issue we performed computational experiments with our improved mesoscopic model. Our results show that changing electrodes work function affects simultaneously all optoelectronic mechanisms that rule exciton and charges dynamics, and thus the device performance.Fundação para a Ciência e a Tecnologia (FCT

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

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

Physical Fitness Differences Between Prepubescent Boys and Girls

The purpose of this study was to analyze in which physical capabilities boys and girls are closer or distant. An additional objective was to find which of the body fat, physical activity, and somatotype factors have a greater effect on prepubescent children's physical fitness. This was a cross-sectional study involving 312 children (10.8 ± 0.4 years). The physical fitness assessment employed sets of aerobic fitness, strength, flexibility, speed, agility, and balance. The boys presented higher values in all selected tests, except tests of balance and flexibility, in which girls scored better. Gender differences in the physical fitness were greatest in the explosive strength of upper (p ≤ 0.01, η(p)(2) = 0.09) and lower limbs (p ≤ 0.01, η(p)(2) = 0.08), although with a medium-size effect of gender, and smaller in the abdominal (p > 0.05, η(p)(2) = 0.007) and upper limbs (p > 0.05, η(p)(2) = 0.003) muscular endurance, and trunk extensor strength and flexibility (p > 0.05, η(p)(2) = 0.001). The endomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the girls, and the ectomorphic (p ≤ 0.01, η(p)(2) = 0.31) and mesomorphic (p ≤ 0.01, η(p)(2) = 0.26) in the boys, had the high-sized effect on the physical fitness. The physical activity in the girls, and the endomorphic and body fat in the boys, did not have a significant effect. These findings can help in the planning of activities that take into account the success and motivation of both boys and girls and thus increase levels of physical activity and physical fitness at school. However, in prepubescent children, one cannot neglect the influence of genetic determinism, observed from the morphoconstitutional point of view.info:eu-repo/semantics/publishedVersio

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

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

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

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