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• SFE of microalgae Aurantiochytrium sp. and Soxhlet extraction (n-hexane & dichloromethane). • Maximization of total extraction yield, DHA & total phenolics content, & antioxidant capacity. • Design of experiments with 3 factors and 2 levels (200−300 bar, 40−80 °C, 6–12 g C O 2 m i n - 1). • Obtained DHA content 3.5-fold richer than fish oil, and 7.9-fold richer than other microalgaes. The microalgae Aurantiochytrium sp. is a strong alternative source of ω-3 fatty acids, including docosahexaenoic acid (DHA). This work encompasses the optimization of SFE conditions to maximize the total extraction yield η T o t a l , DHA content (C D H A), total phenolics content (T P C), and antioxidant capacity (A O C) of the extracts produced from Aurantiochytrium sp. biomass. A full factorial experimental plan was performed, comprising three factors (pressure, temperature, and flow rate) and two levels (200−300 bar, 40−80 °C, and 6–12 g m i n - 1 , respectively). The maximum and minimum experimental results were η T o t a l = 2.1 and 13.4 wt.%, C D H A = 27.3 and 39.3 wt.%, T P C = 1.19 and 2.24 m g G A E g e x t r a c t - 1 , and A O C = 0.3 and 1.4 m g T E A C g e x t r a c t - 1. Under the studied experimental conditions, increasing pressure up to 300 bar is the optimum to rise both η T o t a l and C D H A. Temperature increase from 40 to 80 °C leads to opposing effects: it favors the concentration of phenolics in the supercritical extracts at the expenses of decreasing DHA content and total yield. Surface models were adjusted to η T o t a l , C D H A and T P C data, and the goodness of the fits ranged from coefficients of determination of 0.752-0.711 (T P C) to 0.997-0.994 (C D H A). Under optimized conditions, supercritical extracts exhibited a DHA content more than 3.5-fold richer than fish oil, and 7.9-fold richer than the best alternative microalgae species (Pavlova lutheri) found in the literature. [ABSTRACT FROM AUTHOR]

The Ambiguity Dilution of Precision (ADOP) is a well-known scalar measure that can be used to infer the strength of the Global Navigation Satellite System (GNSS) model of the carrier phase ambiguities involved in precise relative GNSS positioning. Odijk and Teunissen (2008a) derived closed-form expressions for single-baseline GNSS models that allow verifying the factors affecting the ambiguity resolution as well as the probability of its correct resolution as integer values. However, this weighted-ionosphere ADOP closed form assumes that the standard deviation of the ionosphere delay is dependent on a function associated with the baseline length. This means that a baseline of the same length at different locations around the world and in different moments in time would have the same standard deviation, which in practice is not true. This becomes even worse in regions like Brazil, where the ionospheric anomalies are more intense and frequent, especially in periods of high solar activity. In this work, a new method for calculating the ionospheric delay standard deviation that considers the ionospheric scintillation S4 index is proposed to improve the closed-form ADOP performance. Experiments with a baseline of 280 m located in Presidente Prudente, Brazil (magnetic latitude of around −13°), were carried out. The results showed that in periods of both weak and strong ionospheric scintillation, the introduction of S4 into the ionospheric delay standard deviation was beneficial for ADOP. The average improvement of the ADOP closed form was of around 72% in the analyzed period of weak scintillation and of 35% in the period of strong scintillation. In addition, the results showed that in periods of strong scintillation, relative positioning accuracy is around 100 times worse, up to 30 m, when compared to periods of weak ionospheric scintillation. [ABSTRACT FROM AUTHOR]

• Actetylcarvacrol impairs R. microplus reproduction due to morphological alterations in oocytes. • The main alterations were found in the chorion, cytoplasm and nucleolus. • The semiquantitative analysis used facilitates comparisons between chemicals. Rhipicephalus microplus , commonly known as southern cattle tick, causes huge economic losses in the cattle industry. Its infestation affects the production of meat and milk and causes discomfort to hosts. In addition, it is the vector of Babesia spp. and Anaplasma spp. The most frequent method used to control these parasites is through synthetic acaricides. However, their indiscriminate use can be toxic for hosts and environment as well as cause selection of resistant ticks. Plant extracts and essential oils emerge as promising alternatives to manage tick infestation. Carvacrol, an aromatic monoterpene extracted from plants, has recognized antimicrobial, antioxidant, insecticidal, repellent and acaricidal activities. Acetylation of carvacrol is believed to enhance its nematicidal and acaricidal activities and to decrease its toxicity to hosts. Thus, the aim of this study was to evaluate the effect of different concentrations of acetylcarvacrol in the morphology of ovaries of engorged R. microplus ticks. The most remarkable morphological alterations found in the female germ cells were irregular and thicker chorion, decreasing in size and irregular shape of female germ cells (oocytes), cytoplasmatic vacuolization as well as ring-shaped nucleoli. These alterations were analyzed through a semi-quantitative method proposed in this study for ixodid ticks. Treatment group IV, which was exposed to 4.5 μL/mL of carvacrol acetate, showed the most significant alterations, and it was also statistically different when compared to control groups. Therefore, sublethal concentrations of acetylcarvacrol demonstrated to impact the reproductive system of R. microplus by causing several damages in the female germ cells. This would hinder the generation of new individuals, probably contributing for a long-term control of tick infestation. [ABSTRACT FROM AUTHOR]

Bio-oils are typically produced by pyrolysis processes. Bio-oils can be used directly in a generator to produce electricity or upgraded to produce transportation fuels. Nowadays the interest is that they come out in a biorefinery context. This paper compares bio-oil production within three possible procedures. Targeting the bio-oil product, in virtual biorefinery #1, microalgae is processed by solvent ultrasound-assisted extraction, and lipids follow transesterification; in virtual biorefinery #2, bio-oil comes out from fresh microalgae pyrolysis, and, finally, in virtual biorefinery #3, lipid extraction leftovers proceed for slow pyrolysis. Solvent ultrasound-assisted extraction and slow pyrolysis are tested and measured experimentally using three microalgae as feedstock: Chlorella vulgaris , Nannochloropsis oculata , and Scenedesmus obliquus . These stand-alone processes are analyzed aiming to provide the best option in a virtual biorefinery context. Although very fast/slow pyrolysis produces markedly different products, previous thermogravimetry analysis allowed choosing an adequate pyrolysis temperature. Nevertheless, the influence of temperature, catalyst and nitrogen flow is depicted. The comparison indicators for final remarks relate to final energy consumption and greenhouse gas emissions. Conditions that favor bio-oil production may not be favorable in terms of energy required per mass or energy output. If mass allocation criterion is used lipid extraction followed by slow pyrolysis of the leftovers is advantageous over slow pyrolysis of fresh dry microalgae. Still the fossil energy input largely surpasses the bio-oil energy content. [ABSTRACT FROM AUTHOR]

Doping and strain engineering are effective tuning approaches for improving the electrochemical performance of materials in batteries and catalytic applications. This work investigates the adsorption and diffusion properties of lithium (Li) atoms on two-dimensional (2D) titanium disulfide (TiS 2) using first-principles calculations. This work also investigates the effects of strain and heteroatom doping with manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) on the performance of 2D TiS 2 and the prospects for its use in Li-ion batteries. Compared to other 2D materials such as VS 2 and MoS 2 , our findings reveal that pristine TiS 2 has a strong Li-ion adsorption energy of −2.03 eV, which improves to −2.07 eV and −2.62 eV by strain and doping, respectively. While no noticeable decrease in the diffusion energy barrier of the material is observed due to strain, the substitution of Ti with Co atoms results in a considerable reduction in the energy barrier from 0.19 eV to 0.12 eV. We also observed a dramatic enhancement of the open circuit voltage by ∼ 43% when a tensile strain of 4% is applied, and by ∼ 54% when the Co doping concentration is increased to 22.2%. The results indicate that 2D TiS 2 is a potential contender for battery anodes as well as electrocatalytic applications, with doping and strain engineering further enhancing the properties of the material. [Display omitted] • DFT study of Li-ion adsorption and diffusion on pristine, strained and doped TiS 2. • Doping significantly enhances the adsorption of Li ions on the surface of TiS 2. • TiS 2 doped with Co atoms has a low Li-ion diffusion barrier and a high capacity. [ABSTRACT FROM AUTHOR]

• The experimental results show that the wall significantly changes the mean pressure distribution around the wing. • The comparisons of the experimental and numerical results indicates that the γ - R e θ SST model is a good choice for junction flow simulations at the preliminary design stage. • The Reynolds Stress models, however, do not show any advantage in predicting the mean pressure field. A junction flow formed between a wing and a wall is ubiquitous in engineering applications and impacts aerodynamic performance and energy consumption. This paper studies the mean pressure field in the junction region around wall-mounted wings with NACA 0012 and NACA 6412 wing section profiles. Mean surface pressure measurements have been performed in the University of New South Wales large aerodynamic wind tunnel at a chord-based Reynolds number of 87,000 and a range of angles of attack spanning 0 - 12 degrees. Results of three-dimensional RANS simulations for both wing profiles using five turbulence models are also presented. The experimental results show that the wall significantly changes the mean pressure distribution around the wing, especially in the region upstream of the boundary layer reattachment point. The γ - R e θ SST turbulence model has a transition predictor for the boundary layer above the airfoil far away from the bottom wall and delivers the most accurate pressure field prediction in the wing-wall junction region. The junction pressure structure is well-captured except the LE stagnation region and the suction side of the trailing edge. The Reynolds Stress models, however, do not show any advantage in predicting the mean pressure field at high angles of attack. [ABSTRACT FROM AUTHOR]

Abstract: The US Department of Energy is considering a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with dense uranium nitride (UN) kernels with diameters of 650 or 800μm. The objectives of this effort are to make uranium oxide microspheres with adequately dispersed carbon nanoparticles and to convert these microspheres into UN spheres, which could be then sintered into kernels. Recent improvements to the internal gelation process were successfully applied to the production of uranium gel spheres with different concentrations of carbon black. After the spheres were washed and dried, a simple two-step heat profile was used to produce porous microspheres with a chemical composition of UC0.07−0.10N0.90−0.93. The first step involved heating the microspheres to 2023K in a vacuum, and in the second step, the microspheres were held at 1873K for 6h in flowing nitrogen. [Copyright &y& Elsevier]

Abstract: This paper presents and discusses a hybrid-mixed stress finite element model based on the use of polynomial wavelets for the physically non-linear analysis of concrete structures. The effective stress and the displacement fields in the domain of each element and the displacements on the static boundary are independently approximated. As none of the fundamental equations is locally enforced a priori, the hybrid-mixed stress formulation enables the use of a wide range of functions. In the numerical model reported here, all approximations are defined using complete sets of polynomial wavelets. These bases present some important features. In one hand, the functions are orthogonal, which is an important issue when implementing hybrid-mixed stress elements as it ensures high levels of sparsity. On the other hand, the polynomial wavelet basis is defined through linear combinations of Legendre polynomials. This fact enables the use of closed-form solutions for the computation of the integrations involved in the definition of all linear structural operators. A simple isotropic damage model is adopted and a non-local integral formulation where the strain energy release rate is taken as the non-local variable is considered. The numerical model is both incremental and iterative and is solved with a modified Newton–Raphson method that uses the secant matrix. Classical benchmark tests are chosen to illustrate the use of the model under discussion and to assess its numerical performance. [Copyright &y& Elsevier]

Abstract: NO x emission standards are becoming stringiest over the world especially for heavy-duty vehicles. To comply with current and future regulations some vehicle manufacturers are adopting exhaust aftertreatment systems known as Selective Catalytic Reduction (SCR). The catalysts are based on Vanadium (Va) and the reductant agent based on ammonia. However, Va is listed on the California Proposition 65 List as potentially causing cancer and alternatives are being studied. This paper presents a model based on neural networks that integrated with a road vehicle simulator allows to estimate NO x emission factors for different powertrain configurations, along different driving conditions, and covering commercial, zeolite and mordenite alternatives as the base monolith for SCR. The research included the experimental study of copper based and iron based zeolites (ZSM5 and Cuban natural mordenite). The response of NO x conversion efficiency was monitored in a laboratory for varying space velocity, oxygen, sulfur, water, NO x and SO2 emulating the conditions of a Diesel engine exhaust along a trip. The experimental data was used for training neural networks and obtaining a mathematical correlation between the outputs and inputs of the SCR system. The developed correlation was integrated with ADVISOR road vehicle simulator to obtain NO x emission factors and to test each SCR system installed on light-duty and heavy-duty vehicles for standardized driving cycles and real measured driving cycles. Despite having lower NO x conversion efficiencies than the CATCO in the ETC/ESC and NEDC cycles, FeZSM5 maintain the Euro regulation level. Therefore FeZSM5 can be a possible candidate as far as pollutants regulation is considered. [Copyright &y& Elsevier]

Abstract: In recent years, some research effort has been devoted to the development of non-conventional finite element models for the analysis of concrete structures. These models use continuum damage mechanics to represent the physically non-linear behavior of this quasi-brittle material. Two alternative approaches proved to be robust and computationally competitive when compared with the classical displacement finite element implementations. The first corresponds to the hybrid–mixed stress model where both the effective stress and the displacement fields are independently modeled in the domain of each finite element and the displacements are approximated along the static boundary, which is considered to include the inter-element edges. The second approach corresponds to a hybrid–displacement model. In this case, the displacements in the domain of each element and the tractions along the kinematic boundary are independently approximated. Since it is a displacement model, the inter-element boundaries are now included in the kinematic boundary. In both models, complete sets of orthonormal Legendre polynomials are used to define all approximations required, so very effective p-refinement procedures can be implemented. This paper illustrates the numerical performance of these two alternative approaches and compares their efficiency and accuracy with the classical finite element models. For this purpose, a set of numerical tests is presented and discussed. [Copyright &y& Elsevier]

Abstract: This paper discusses three hybrid-displacement finite element formulations for the simulation of strain localization based on nonlocal damage theory. An isotropic integral nonlocal damage model is chosen. The hybrid finite element formulations adopted in this work are developed from first principles of Mechanics. The first one defines the domain approximations using the Trefftz functions derived for the linear elastic regime. When damage appears the hybrid-Trefftz displacement formulation degenerates into an hybrid-displacement formulation. The second formulation uses an enriched Trefftz basis with the consideration of local Heaviside functions. The third formulation uses orthonormal Legendre polynomials for the domain approximations. A set of benchmark tests is presented and discussed in order to compare the performance and accuracy of the different models. It is shown that the proposed hybrid-Trefftz formulation allows the reproduction of the general behavior of the structure but does not lead to a correct simulation of the strain tensor evolution. The hybrid-displacement formulation that uses orthonormal Legendre polynomials gives coherent results, so it appears to be a promising field of investigation. [Copyright &y& Elsevier]

Abstract: The conversion efficiency of a catalytic converter, mounted on a vehicle equipped with a 2.8l spark ignition engine, was evaluated under steady state operating conditions. The inlet and outlet chemical species concentration, temperature and air fuel ratio (A/F) were measured as a function of the brake mean effective pressure (BMEP) and engine speed (rpm). Oil temperature, coolant temperature, brake power and spark advance were also monitored. In parallel, a mathematical model for the catalytic converter has been developed. The main inputs of the model are the temperature, flow rate, chemical species mass flow and local A/F ratio as measured at the catalyst inlet section. The main conclusions are: (i) the exhaust gas and substrate wall temperatures at the catalyst outlet increase with BMEP and rpm; (ii) the HC conversion efficiency increases with the value of BMEP up to a maximum beyond which it decreases; (iii) the CO conversion efficiencies typically increase with BMEP; (iv) the NO x conversion efficiency remains nearly constant regardless of BMEP and rpm; (v) except for idle, the NO x conversion efficiency is typically the highest, followed in turn by the CO and HC conversion efficiencies; (vi) conversion efficiencies are lower for idle conditions, which can be a problem under traffic conditions where idle is a common situation; (vii) regardless of rpm and load, for the same flow rate the conversion efficiency is about the same; (viii) the model predictions slightly over estimate the exhaust gas temperature data at the catalyst outlet section with the observed differences decreasing with BMEP and engine speed; (ix) in general, the model predictions of the conversion efficiencies are satisfactory. [Copyright &y& Elsevier]

Abstract: The use of numerical models for estimating fuel consumption and emission of HC, CO, NO x and CO2 of gasoline vehicles, under urban driving conditions, is examined. Three models were selected for evaluation: EcoGest, CMEM and ADVISOR. The models were used to simulate a sample of 14 urban trips for two 1999 Ford Taurus vehicles. Trip statistics were monitored on-board of the passenger vehicles across a variety of traffic conditions, using a portable emissions measurement device (PEMS). A key conclusion is that the tested models can be used with relatively high confidence to predict fuel consumption and CO2 emissions. However, results must be viewed with greater caution when it comes to predictions for other pollutants. [Copyright &y& Elsevier]

Abstract: Currently, oil based fuels are the primary energy source of road transport. The growing need for oil independence and CO2 mitigation has lead to the increasing importance of alternative fuel usage. CO2 is produced not only as the fuel is used in the vehicle (tank-to-wheel contribution), but also upstream, from the fuel extraction to the refueling station (well-to-tank contribution), and the life cycle of the fuel production (well-to-wheel contribution) must be considered in order to analyse the global impact of the fuel utilization. A road vehicle tank-to-wheel analysis tool that may be integrated with well-to-tank models was developed in the present study. The integration in a demonstration case study allowed to perform a life cycle assessment concerning the utilization of diesel and natural gas fuels in a specific network line of a bus transit company operating in the city of Porto, Portugal. [Copyright &y& Elsevier]