924 research outputs found
Combining gait optimization with passive system to increase the energy efficiency of a humanoid robot walking movement
There are several approaches to create the Humanoid robot gait planning. This problem presents a large number of unknown parameters that should be found to make the humanoid robot to walk. Optimization in simulation models can be used to find the gait based on several criteria such as energy minimization, acceleration, step length among the others. The energy consumption can also be reduced with elastic elements coupled to each joint. The presented paper addresses an optimization method, the Stretched Simulated Annealing, that runs in an accurate and stable simulation model to find the optimal gait combined with elastic elements. Final results demonstrate that optimization is a valid gait planning technique.This work was been supported by FCT (Fundação para a Ciência e Tecnologia) in the scope of the project PEst-OE/EEI/UI0319/2014.info:eu-repo/semantics/publishedVersio
Proteolysis in model portuguese cheeses: Effects of rennet and starter culture
To shed further light onto the mechanisms of proteolysis that prevail throughout ripening of Portuguese cheeses, model cheeses were
manufactured from bovine milk, following as much as possible traditional manufacture practices – using either animal or plant rennet. The individual role upon proteolysis of two (wild) strains of lactic acid bacteria – viz. Lactococcus lactis and Lactobacillus brevis, which are normally found to high viable numbers in said cheeses, was also considered, either as single or mixed cultures. Our experimental
results confirmed the influence of rennet on the proteolysis extent, but not on proteolysis depth. On the other hand, the aforementioned strains clearly improved release of medium- and small-sized peptides, and contributed as well to the free amino acid pool in cheese
Enzymes and secondary metabolites profiles of Gnomoniopsis smithogilvyi are affected by chestnut medium
Chestnut tree (Castanea sativa Mill) is a crop with high economic and social importance in
Trás-os-Montes Region. The pre and post-harvest quality of its nuts can be affected by many
factors, being the lasses dueto fungi very large. During the last decade a new endophyte
fungus, Gnomoniopsis smithogilvyi, causing brown rot, has been isolated from both rotten and
healthy fruits, and its growth seems to be related with the increase of air temperatura and
rainfall during spring. The present study aims to understand the influence of chestnut substrate
on G. smithogilvyi biochemistry, in arder to develop strategies to reduce its incidence in the
fruit and improve the contrai of brown rot. lnitially, the presence of the enzymes involved in the
decomposition of chestnuts, such as amylase, proteases, carboxymethylcellulase (CMCase),
~-glucosidase, xylanase, among others, was investigated. Further, some hydrolase activities
were evaluated in two isolates of G. smithogilvyi incubated in potato (PDB) and chestnut media
(CM) along an incubation period (3, 7 and 14 days), in arder to study the effects "isolate",
"medium" and "incubation period" on enzymes production. Also, the synthesis of secondary
metabolites in fungai dry biomass was assessed by Liquid chromatography coupled to tandem
mass spectrometry (LC-MS/MS). Ali isolates produced the enzymes screened and, in general,
the enzyme production varied between the isolates (P< 0.0000), the media (P< 0.0000) and
along the incubation period (P< 0.0000). Amylase activity was positively correlated with
xylanase (P< 0.0001), CMCase (P< 0.0001), and Avicelase {P< 0.01), xylanase with CMCase
(P< 0.01) and ~-glucosidase with Avicelase (P< 0.0001 ). By contrast, ~-glucosidase was
negatively correlated with CMCase {P< 0.01 ). Twenty secondary metabolites were detected
along the incubation: eight in both isolates and media, tive and three only in isolates grew in
PD o r CM, respectively. Some of these metabolites had been associated with other fungi and
have known biological activities.This work was suported by "ValorCast- Valorização da castanha e otimização da sua comercialização" (PDR2020-1.0.1-
FEADER-032034}, funded by Fundo Europeu Agrfcola de Desenvolvimento Rural (FEADER} and the Portuguesa Government (Ação
1.1 Grupos Operacionais, Medida 1. Inovação, PDR 2020- Programa de Desenvolvimento Rural do Continente). AS, IF, JGL, AAD, are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CITAB (UIDB/04033/2020) and PR to CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio
Optimization of a humanoid robot gait: multilocal optimization approach
The humanoid robot gait planning presents a large number of unknown parameters that should be found to make the humanoid robot to walk. There are several approaches to achieve the gait but an accurate simulation can be used to compute it. A stable joint model of a humanoid robot is used in simulation to optimize the gait parameters. The optimization is based on the stretched simulated annealing with the multilocal algorithm approach. Final results prove the benefits of the presented optimization algorithm.This work is financed by the ERDF - European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT -Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within projects FCOMP-01-0124-FEDER-022701 and FCOMP-01-0124-FEDER-022674
Functional modifications associated with gastrointestinal tract organogenesis during metamorphosis in Atlantic halibut (Hippoglossus hippoglossus)
Background: Flatfish metamorphosis is a hormone regulated post-embryonic developmental event that transforms a symmetric larva into an asymmetric juvenile. In altricial-gastric teleost fish, differentiation of the stomach takes place after the onset of first feeding, and during metamorphosis dramatic molecular and morphological modifications of the gastrointestinal (GI-) tract occur. Here we present the functional ontogeny of the developing GI-tract from an integrative perspective in the pleuronectiforme Atlantic halibut, and test the hypothesis that the multiple functions of the teleost stomach develop synchronously during metamorphosis.
Results: Onset of gastric function was determined with several approaches (anatomical, biochemical, molecular and in vivo observations). In vivo pH analysis in the GI-tract lumen combined with quantitative PCR (qPCR) of α and β subunits of the gastric proton pump (H+/K+-ATPase) and pepsinogen A2 indicated that gastric proteolytic capacity is established during the climax of metamorphosis. Transcript abundance of ghrelin, a putative orexigenic signalling molecule produced in the developing stomach, correlated (p < 0.05) with the emergence of gastric proteolytic activity, suggesting that the stomach’s role in appetite regulation occurs simultaneously with the establishment of proteolytic function. A 3D models series of the GI-tract development indicated a functional pyloric sphincter prior to first feeding. Observations of fed larvae in vivo confirmed that stomach reservoir function was established before metamorphosis, and was thus independent of this event. Mechanical breakdown of food and transportation of chyme through the GI-tract was observed in vivo and resulted from phasic and propagating contractions established well before metamorphosis. The number of contractions in the midgut decreased at metamorphic climax synchronously with establishment of the stomach’s proteolytic capacity and its increased peristaltic activity. Putative osmoregulatory competence of the GI-tract, inferred by abundance of Na+/K+-ATPase α transcripts, was already established at the onset of exogenous feeding and was unmodified by metamorphosis.Conclusions: The functional specialization of the GI-tract was not exclusive to metamorphosis, and its osmoregulatory capacity and reservoir function were established before first feeding. Nonetheless, acid production and the proteolytic capacity of the stomach coincided with metamorphic climax, and also marked the onset of the stomach’s involvement in appetite regulation via ghrelin.Peer Reviewe
Human tendon-derived cell sheets created by magnetic force-based tissue engineering hold tenogenic and immunomodulatory potential
Cell sheet technology and magnetic based tissue engineering hold the potential to become instrumen- tal in developing magnetically responsive living tissues analogues that can be potentially used both for modeling and therapeutical purposes. Cell sheet constructions more closely recreate physiological niches, through the preservation of contiguous cells and cell-ECM interactions, which assist the cellular guidance in regenerative processes. We herein propose to use magnetically assisted cell sheets (magCSs) constructed with human tendon- derived cells (hTDCs) and magnetic nanoparticles to study inflammation activity upon magCSs exposure to IL-1 β, anticipating its added value for tendon disease modeling. Our results show that IL-1 βinduces an inflammatory profile in magCSs, supporting its in vitro use to en- lighten inflammation mediated events in tendon cells. Moreover, the response of magCSs to IL-1 βis mod- ulated by pulsed electromagnetic field (PEMF) stimulation, favoring the expression of anti-inflammatory genes, which seems to be associated to MAPK(ERK1/2) pathway. The anti-inflammatory response to PEMF together with the immunomodulatory potential of magCSs opens new perspectives for their applicability on tendon regeneration that goes beyond advanced cell based modeling.This research was funded by the ERC CoG MagTendon (No. 772817), Fundação para a Ciência e Tecnologia (FCT) for the doctoral grant PD/BD/128089/2016 of A. Vinhas and the project MagTT PTDC/CTM-CTM/29930/2017 (POCI-01-0145-FEDER-29930), project
Norte-01-0145-FEDER-02219015 supported by Norte Portugal Regional Operational Programme (NORTE 2020) and EC Twinning project Achilles (No. 810850)
Multiple linear and principal component regressions for modelling ecotoxicity bioassay response
The ecotoxicological response of the living organisms in an aquatic system depends on the physical, chemical and bacteriological
variables, as well as the interactions between them. An important challenge to scientists is to understand the
interaction and behaviour of factors involved in a multidimensional process such as the ecotoxicological response.With this
aim, multiple linear regression (MLR) and principal component regression were applied to the ecotoxicity bioassay response
of Chlorella vulgaris and Vibrio fischeri in water collected at seven sites of Leça river during five monitoring campaigns
(February, May, June, August and September of 2006). The river water characterization included the analysis of 22 physicochemical
and 3 microbiological parameters. The model that best fitted the data was MLR, which shows: (i) a negative
correlation with dissolved organic carbon, zinc and manganese, and a positive one with turbidity and arsenic, regarding
C. vulgaris toxic response; (ii) a negative correlation with conductivity and turbidity and a positive one with phosphorus,
hardness, iron, mercury, arsenic and faecal coliforms, concerning V. fischeri toxic response. This integrated assessment may
allow the evaluation of the effect of future pollution abatement measures over the water quality of Leça River
Innovative robot design for cleaning solar panels
The accumulation of dust particles on the solar panels decrease the total amount of solar energy received by the Photovoltaic panel (PV) and, it has also been proven that the increase of temperature reduces the overall efficiency. These effects have been studied by different researchers based on collected data comparison. As both of these parameters have a negative effect on the efficiency of the solar panel, it is essential to keep them clean and at low temperatures. The use of technologies, such as robots, is an effective way of carrying out repetitive tasks at low cost and in a short time. This work consists of developing a robot capable of cleaning and cooling the solar panels, based on images acquired through a camera positioned directly towards the panels, thus maintaining periodic cleaning in order to increase its efficiency. The preliminary results demonstrate the possibility of using this approach for the accomplishment of this task.This work is financed by National Funds through the Portuguese funding agency, FCT - Fundação
para a Ciência e a Tecnologia within project UIDB/50014/2020.info:eu-repo/semantics/publishedVersio
Layer-by-layer deposition of antimicrobial polymers on cellulosic fibers : a new strategy to develop bioactive textiles
In recent years, there has been an increase of infectious diseases caused by different microorganisms and the development of antibiotic resistance. In this way, the search for new and efficient antibacterial materials is imperative. The main polysaccharides currently used in the biomedical and pharmaceutical domains are chitin and its derivative chitosan (CH) and alginates (ALG). In this study, a simple technique of Layer by Layer (LbL) of applying polycation CH and polyanion ALG was used to prepare CH/ALG multilayers on cotton samples via the electrostatic assembly with success. The CH/ALG cotton samples (functionalized) were investigated for their antibacterial properties towards Staphylococcus aureus and Klebsiella pneumonia using the international standard method JIS L 1902:2002. The antibacterial activity of the functionalized samples was tested in terms of bacteriostatic and bactericidal activity, and results showed that the samples exhibited a bacteriostatic effect on the two bacteria tested, as expected. In addition, samples with five layers (CH/ALG/CH/ALG/CH) were more effective in inhibiting bacterial growth. This new coating for cellulosic fibers is a new strategy and may open new avenues for the development of antimicrobial polymers with potential application in health-care field.The authors would like to thank Fundacao para a Ciencia e Tecnologia (FCT) for the funding granted concerning the project - PTDC/EBB-BIO/113671/2009 (FCOMP-01-0124-FEDER-014752) Skin2Tex. Also, we would like to thank Fundo Europeu de Desenvolvimento Regional (FEDER) through COMPETE - Programa Operacional Factores de Competitividade (POFC) for the co-funding
Rheological, textural and microstructural features of probiotic whey cheeses
Whey cheeses have been manufactured with probiotic bacteria e viz. Bifidobacterium animalis Bo and Lactobacillus casei LAFTIrL26, from combinations of bovine whey and milk, following protein denaturation
at 90 ºC; they were subsequently inoculated (at 10%) with those strains, and homogenized afterwards; additives such as salt and sugar were then incorporated; and the resulting solid matrices were stored at 7º C for up to 21 d. Oscillatory measurements and instrumental texture profile analyses were
performed, and sensory analyses were carried out by a trained panel. Microstructural features were in addition ascertained by scanning electron microscopy. L. casei exhibited a higher acidifying activity than B. animalis, which produced distinct textures; higher firmness and viscoelasticity were indeed found in matrices inoculated with the former. Incorporation of sugar and L. casei favoured consumer acceptability, relative to plain matrices. Microstructural differences
were detected between matrices at different times of storage and formulated with distinct additives.info:eu-repo/semantics/acceptedVersionhttps://creativecommons.org/licenses/by-nc-nd/4.0
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