Crashworthiness study on hybrid energy absorbers as vertical struts in civil aircraft fuselage designs

[Abstract:] This research concerns the crashworthiness study and enhancement of commercial aircraft fuselage structures by incorporating crushable hybrid energy absorbers to work as vertical struts. To assess their contribution on a representative aircraft structure, a numerical simulation of a Boeing 737-200 drop test is developed and validated with experimental data available in the literature. The fuselage section is then simulated both with and without the fuel tank, showing more harmful effects for the latter scenario. The numerical model accurately captures the experiment’s collapse process with low artificial energy ratios. Later, four vertical hybrid energy absorbers designed for programmed and progressive collapse, are added in the cargo compartment, connecting the underfloor beams and the frames. Different designs and positions are studied, combining aluminum tubes with square and circular cross-sections, filled with a core made from a GFRP skeleton and foam extrusions. Acceleration graphs show a reduction in passenger injury levels from severe to moderate according to an Eiband diagram when energy absorbers are fitted. Energy trends from the hybrid absorbers are also monitored, with dissipation of up to 10 kJ of the fuselage’s kinetic energy through plastic deformation and collapse. Results also show a significant improvement on the global crashworthiness of the fuselage, leading to an increase in plastic dissipation by the frames from 76 kJ to 122 kJ and a reduction on the accelerations up to 50% when the energy-absorbing structures are added.Ministerio de Economía, Industria, y Competitividad. MINECO; DPI2016-76934-RMinisterio de Economía, Industria, y Competitividad; DPI2016-76934-

Optimisation of thin-walled hybrid vertical struts for crashworthy aircraft designs

[Abstract:] This research concerns the crashworthiness enhancement of a model of a Boeing 737-200 fuselage section. Using a validated numerical specimen, four thin-walled crushable hybrid energy absorbers are added to the aircraft to work as vertical struts. The absorbers are composed of a hollow aluminium tube, a star-shaped glass fibre–reinforced polymer inner matrix and foam extrusions. The absorbers—with variable tube edge and thickness, composite thickness and core height—are single- and multi-objectively optimised. Surrogate models and genetic algorithms are used for the minimisation of acceleration loads, injury levels and the strut’s weight. Results yield a more efficient frames’ collapse evolution with plastic dissipation increased by over 50%. Consequently, acceleration peaks are up to 50% lower at the two measured locations while maintaining low mass values. Injury levels were also reduced from severe to moderate according to an Eiband diagram.Ministerio de Economía y Competitividad; DPI2016-76934-

The effect of menthol rinsing before intermittent exercise on physiological, physical, and thermo-behavioral responses of male football referees in hot and humid environment

IntroductionIn the current experiment, we aimed to evaluate whether eliciting pre-exercise non-thermal cooling sensations would alter perceptual measures, and physical and physiological responses in football referees.MethodsNine highly trained male football referees undertook two 45-minute intermittent exercise protocols in hot and humid conditions (34.2 ± 0.6°C, 62.5 ± 1.0% relative humidity). In a randomized counterbalanced crossover design, 1 of 2 beverages were given before the warm-up: a 0.01% menthol solution or a placebo noncaloric solution. Physical performance was quantified as total distance covered in each of the three 15-minute exercise blocks. Core temperature, heart rate, thermal sensation and thermal comfort were measured at rest and after each exercise block.ResultsNo changes were observed between trials and over time for distance covered. No main effect of mouth rinse was observed for core temperature and heart rate, but both increased over time in all conditions (P < 0.001). Thermal sensation and thermal comfort were significantly improved with menthol after mouth-rinsing (P < 0.05), but with no differences at any other time-point.DiscussionThese results indicate that non-thermal cooling oral stimuli provide immediate behavioral changes but may not influence physiological or physical responses in football referees, during intermittent exercise in hot and humid environments. Clinical Trial Registrationwww.clinicaltrials.gov, identifier NCT05632692

Optimisation of lab-scale continuous alcohol-free beer production

In order to study the formation and conversion of the most important flavour compounds, the real wort used in alcohol-free beer fermentation was mimicked by a complex model medium containing glucose, yeast extract, and selected aldehydes. The fermentation experiments were carried out in a continuously operating gas-lift reactor with brewing yeast immobilised on spent grains (brewing by-product). During the continuous experiment, parameters such as oxygen supply, residence time (Rt), and temperature (T) were varied to find the optimal conditions for the alcohol-free beer production. The formation of ethanol, higher alcohols (HA), esters (ES), as well as the reduction of aldehydes and consumption of glucose were observed. The results suggest that the process parameters represent a powerful tool in controlling the degree of fermentation and flavour formation brought about by immobilised biocatalyst. Subsequently, the optimised process parameters were used to produce real alcohol-free beer during continuous fermentation. The final product was compared with batch fermented alcohol-free beers using the methods of instrumental and sensorial analysis.Ministry of Education, Youth and Sports of the Czech Republi

Screening of key abiotic factors for biomass production of Pavlova gyrans

Microalgae biomass is an important source of bioactive compounds with commercial interest (e.g., polyunsaturated fatty acids, proteins, pigments) for several industrial sectors such as cosmetics, pharmaceutical, food, and feed. Known for their plasticity and high growth rates under different environments, a precise control of microalgae cultivation is of the utmost importance to maximize biomass productivity and its biochemical composition, reducing, at the same time, the production costs involved. Nutritional conditions and abiotic parameters (e.g., temperature, light) are well-documented in bibliography as the main responsible factors for significant variations in microalgae biomass productivities and bioactive compounds profile. The aim of this study was to evaluate the main culture variables impacting the biomass growth of marine microalga Pavlova gyrans, an interesting species commonly used as feed in aquaculture due to its biochemical profile, which presents high concentrations of polyunsaturated fatty acids (e.g., eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)) and several valuable phytosterols and pigments (e.g., carotenoids). The study was carried out by the application of a Plackett-Burman design (PB) as a screening tool to identify the physicochemical factors that favour biomass productivities (p-value<0.1). Using PB, it was possible to assess the impact of 17 independent variables in the biomass productivity, namely the concentration of each nutrient of the growth medium (13 in total), as well as the salinity, airflow, inoculum size, and light intensity. Biomass productivity ranged from 72 to 256 mg ash-free dry weight (AFDW).L-1.d-1, while the maximum biomass produced ranged from 0.8 to 2.2 g AFDW.L-1.Light intensity (p-value<0.001) and NaNO3 concentration (p-value=0.001) were found to have a positive effect on this parameter. On the contrary, the use of higher concentrations of CuSO4.5H2O negatively affected the growth of P. gyrans (p-value=0.073).This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit. The author Filipe Maciel thanks to the FCT its financial grant (SFRH/BD/133005/2017). This work is funded by the European Regional Development Fund (ERDF) through the Competitiveness factors Operational program – COMPETE and by National Funds through the FCT under the project AgriFood XXI (NORTE- 01-0145-FEDER-000041). This research work was supported by ALGAVALOR - Lisboa-01-0247-FEDER-035234, supported by Operational Programme for Competitiveness and Internationalization (COMPETE2020), by Lisbon Portugal Regional Operational Programme (Lisboa 2020) and by Algarve Regional Operational Programme (Algarve 2020) under the Portugal 2020 Partnership Agreement, through the ERDF.info:eu-repo/semantics/publishedVersio

Does intake of bread supplemented with wheat germ have a preventive role on cardiovascular disease risk markers in healthy volunteers? A randomised, controlled, crossover trial

Objective Intake of whole grains is associated with a reduced risk of cardiovascular disease (CVD). This evidence is also strong for bran alone, but findings about germ are conflicting. Our aim was to elucidate the role of germ in primary prevention of cardiovascular events, and therefore, a staple food was selected for 6g of germ supplementation. This corresponds to sixfold increase in the global mean consumption of germ, while preserving the sensory proprieties of refined bread which is crucial for consumers acceptance. Design Randomised, double-blinded, crossover, controlled clinical trial with 15-week follow-up comprising a 2-week run-in, two intervention periods of 4weeks each and a 5-week washout period. Setting A single centre in the north of Portugal. Participants 55 eligible healthy adults (mean age of 34 years and body mass index between 19 and 38kg/m2) were randomly assigned. Interventions The study consisted of two intervention periods including daily intake of refined wheat bread enriched with 6g of wheat germ and control (non-enriched bread). Outcomes Changes in fasting cholesterol and triglycerides, fasting and postprandial glucose, insulin sensitivity and C reactive protein. Results We observed no significant effect of daily intake of wheat germ on cholesterol and triglycerides levels, on postprandial glucose response and on insulin sensitivity. Incremental area under curve glucose and homeostasis model assessment for insulin resistance did not change, suggesting that 6g of wheat germ have no effect on glucose metabolism. No effect was also observed in the subgroup of participants who complied with the protocol (n=47). Conclusions The absence of alterations on lipid and glucose profiles suggests that germ up to 6g/day may have no preventive effect on CVD risk. However, it is important to investigate other food vehicles that can accommodate higher doses of wheat germ in future studies.This work was supported by the Programa Operacional Competitividade e Internacionalização–COMPETE2020 and by National Funds through Fundação para a Ciência e a Tecnologia-FCT (through the operations FCOMP-01-0202-FEDER-038861 and POCI-01-0145-FEDER-007746).info:eu-repo/semantics/publishedVersio

Unveiling the Antifouling Performance of Different Marine Surfaces and Their Effect on the Development and Structure of Cyanobacterial Biofilms

Since biofilm formation by microfoulers significantly contributes to the fouling process, it is important to evaluate the performance of marine surfaces to prevent biofilm formation, as well as understand their interactions with microfoulers and how these affect biofilm development and structure. In this study, the long-term performance of five surface materials-glass, perspex, polystyrene, epoxy-coated glass, and a silicone hydrogel coating-in inhibiting biofilm formation by cyanobacteria was evaluated. For this purpose, cyanobacterial biofilms were developed under controlled hydrodynamic conditions typically found in marine environments, and the biofilm cell number, wet weight, chlorophyll a content, and biofilm thickness and structure were assessed after 49 days. In order to obtain more insight into the effect of surface properties on biofilm formation, they were characterized concerning their hydrophobicity and roughness. Results demonstrated that silicone hydrogel surfaces were effective in inhibiting cyanobacterial biofilm formation. In fact, biofilms formed on these surfaces showed a lower number of biofilm cells, chlorophyll a content, biofilm thickness, and percentage and size of biofilm empty spaces compared to remaining surfaces. Additionally, our results demonstrated that the surface properties, together with the features of the fouling microorganisms, have a considerable impact on marine biofouling potential

Novel pathways converge with quorum sensing to regulate plant and insect host-specific factors in Erwinia carotovora

Erwinia carotovora Ecc15 is a vector-borne phytopathogen that relies on insects to be transmitted between plant hosts. To interact with its hosts, this bacterium depends on host-specific bacterial traits. Plant tissue maceration depends on production of plant cell wall degrading enzymes (PCWDE), while survival in the digestive tract of the insect requires the Erwinia virulence factor (evf). Evf expression is responsible for the cost of Ecc15 infection in Drosophila melanogaster and overexpression is lethal to the insect host. Therefore, its expression must be well controlled. Expression of evf and PCWDEs is co-regulated by quorum sensing via the transcriptional regulator Hor. Since virulence factors are often controlled by multiple signals, we asked which additional factors regulate evf expression. Using a genetic screen, we identified the sensor histidine kinase arcB and a new TetR-like regulator (named herein as lvtR, after Low Virulence Transcriptional Repressor), as novel regulators not only of evf, but also of pelA, which encodes a major PCWDE. We further demonstrate that arcB and lvtR mutants have reduced plant tissue maceration and reduced development delay and lethality in Drosophila melanogaster, compared to wild-type bacteria. Thus showing the importance of these regulators in the establishment of Erwinia-host-vector interactions. We also found that ArcB and LvtR regulation converges on Hor, independently of quorum sensing, to co-regulate expression of both plant and insect bacterial interaction factors during plant infection. Taken together, our results reveal a novel regulatory hub that enables Ecc15 to integrate quorum sensing responses and environmental cues to co-regulate traits required for infection of both the plant and the insect vector. Moreover, we show that ArcB regulation of bacteria-host interaction processes is conserved in other bacteria.info:eu-repo/semantics/acceptedVersio