Classical Radiation Reaction in Particle-In-Cell Simulations

Under the presence of ultra high intensity lasers or other intense electromagnetic fields the motion of particles in the ultrarelativistic regime can be severely affected by radiation reaction. The standard particle-in-cell (PIC) algorithms do not include radiation reaction effects. Even though this is a well known mechanism, there is not yet a definite algorithm nor a standard technique to include radiation reaction in PIC codes. We have compared several models for the calculation of the radiation reaction force, with the goal of implementing an algorithm for classical radiation reaction in the Osiris framework, a state-of-the-art PIC code. The results of the different models are compared with standard analytical results, and the relevance/advantages of each model are discussed. Numerical issues relevant to PIC codes such as resolution requirements, application of radiation reaction to macro particles and computational cost are also addressed. The Landau and Lifshitz reduced model is chosen for implementation.Comment: 12 pages, 8 figure

Full-scale ab initio 3D PIC simulations of an all-optical radiation reaction configuration at 1021W/cm210^{21}\mathrm{W/cm^2}

Using full-scale 3D particle-in-cell simulations we show that the radiation reaction dominated regime can be reached in an all optical configuration through the collision of a $\sim$1 GeV laser wakefield accelerated (LWFA) electron bunch with a counter propagating laser pulse. In this configuration radiation reaction significantly reduces the energy of the particle bunch, thus providing clear experimental signatures for the process with currently available lasers. We also show that the transition between classical and quantum radiation reaction could be investigated in the same configuration with laser intensities of $10^{24}\mathrm{W/cm^2}$

Particle Merging Algorithm for PIC Codes

Particle-in-cell merging algorithms aim to resample dynamically the six-dimensional phase space occupied by particles without distorting substantially the physical description of the system. Whereas various approaches have been proposed in previous works, none of them seemed to be able to conserve fully charge, momentum, energy and their associated distributions. We describe here an alternative algorithm based on the coalescence of N massive or massless particles, considered to be close enough in phase space, into two new macro-particles. The local conservation of charge, momentum and energy are ensured by the resolution of a system of scalar equations. Various simulation comparisons have been carried out with and without the merging algorithm, from classical plasma physics problems to extreme scenarios where quantum electrodynamics is taken into account, showing in addition to the conservation of local quantities, the good reproducibility of the particle distributions. In case where the number of particles ought to increase exponentially in the simulation box, the dynamical merging permits a considerable speedup, and significant memory savings that otherwise would make the simulations impossible to perform

Goat milk free fatty acid characterization during conventional and ohmic heating pasteurization

The disruption of the milk fat globule membrane can lead to an excessive accumulation of free fatty acids in milk, which is frequently associated with the appearance of rancid flavors. Solid-phase microextraction and gas chromatography techniques have been shown to be useful tools in the quantification of individual free fatty acids in dairy products providing enough sensitivity to detect levels of rancidity in milk. Therefore, the aim of this study was to characterize the short-chain and medium-chain free fatty acid profile in i) raw untreated goat milk; ii) raw goat milk passing through pumps and heating units (plate-and-frame heat exchanger and ohmic heater); and iii) processed goat milk by conventional and ohmic pasteurization to determine the influence of each treatment in the final quality of the milk. Multivariate statistical analysis has shown that the treatments studied were not responsible for the variability found on free fatty acid contents. In particular, it was possible to conclude that ohmic pasteurization at 72°C for 15 s did not promote an extended modification of free fatty acid contents in goat milk when compared with that of conventional pasteurization. Furthermore, principal component analysis showed that the capric acid can be used to discriminate goat’s milk with different free fatty acid concentrations. Hierarchical cluster analysis showed evidence of the existence of correlations between contents of short and medium chain free fatty acids in goat milk

In-season internal and external training load quantification of an elite European soccer team

Elite soccer teams that participate in European competitions need to have players in the best physical and psychological status possible to play matches. As a consequence of congestive schedule, controlling the training load (TL) and thus the level of effort and fatigue of players to reach higher performances during the matches is therefore critical. Therefore, the aim of the current study was to provide the first report of seasonal internal and external training load that included Hooper Index (HI) scores in elite soccer players during an in-season period. Nineteen elite soccer players were sampled, using global position system to collect total distance, high-speed distance (HSD) and average speed (AvS). It was also collected session rating of perceived exertion (s-RPE) and HI scores during the daily training sessions throughout the 2015-2016 in-season period. Data were analysed across ten mesocycles (M: 1 to 10) and collected according to the number of days prior to a one-match week. Total daily distance covered was higher at the start (M1 and M3) compared to the final mesocycle (M10) of the season. M1 (5589m) reached a greater distance than M5 (4473m) (ES = 9.33 [12.70, 5.95]) and M10 (4545m) (ES = 9.84 [13.39, 6.29]). M3 (5691m) reached a greater distance than M5 (ES = 9.07 [12.36, 5.78]), M7 (ES = 6.13 [8.48, 3.79]) and M10 (ES = 9.37 [12.76, 5.98]). High-speed running distance was greater in M1 (227m), than M5 (92m) (ES = 27.95 [37.68, 18.22]) and M10 (138m) (ES = 8.46 [11.55, 5.37]). Interestingly, the s-RPE response was higher in M1 (331au) in comparison to the last mesocycle (M10, 239au). HI showed minor variations across mesocycles and in days prior to the match. Every day prior to a match, all internal and external TL variables expressed significant lower values to other days prior to a match (p<0.01). In general, there were no differences between player positions. Conclusions: Our results reveal that despite the existence of some significant differences between mesocycles, there were minor changes across the in-season period for the internal and external TL variables used. Furthermore, it was observed that MD-1 presented a reduction of external TL (regardless of mesocycle) while internal TL variables did not have the same record during in-season match-day-minus.: The authors state that there were no salaries’ fund from a tobacco company. Also, the authors are not aware of any competing interests. This project was supported by the National Funds through FCT—Portuguese Foundation for Science and Technology (UID/DTP/04045/2013)—and the European Fund for Regional Development (FEDER) allocated by European Union through the COMPETE 2020 Programme (POCI-01-0145- FEDER-006969)—competitiveness and internationalization (POCI). All funding received for this work from any of the following organizations: National Institutes of Health (NIH); Welcome Trust; Howard Hughes Medical Institute (HHMI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.info:eu-repo/semantics/publishedVersio

Optimization of phosphorus recovery from anaerobic digester effluents in agri-industry

Phosphorus (P) is an essential nutrient to sustain life. P is widely used by agriculture sectors as fertilizer to secure food production and sustain human necessities. Since the major sources of P come from non-replaceable and non-renewable natural phosphate rock reserves, it is expected a depletion of this raw material in the next 80 years. In addition, every year, it is estimated that up to 10 Mt are wasted into the hydrosphere causing serious environmental damage in water bodies (e.g., eutrophication). Alongside climate change and the increased risk of draughts in the near future, it is important to guarantee the quality of those water bodies and secure food and feed production in the agriculture sector. Therefore, to reduce the pressure in water bodies, we should increase the efforts to treat wastewater before release, which in turn can be used as a source for P recovery. Thus, the main objective of the present work was the optimization of P recovery from full-scale Anaerobic Digestion (AD) effluents using precipitation methods with the addition of chemical (e.g., Mg, Ca or Fe salts), as well as exploring alternatives to conventional chemicals, such as seawater, bine (Mg-rich sources), and mussel shells and cork ashes (Ca-rich sources). This work is integrated in BIOECONORTE project - water and nutrients management based on BIOrefinery and circular ECOnomy towards a sustainable agri-food system of the NORTE of Portugal. The addition of chemicals was based on the initial concentration of P in the effluent (brewery and dairy industry), and different molar ratios (salt:P) 1:1, 2:1, 3:1 or 4:1 were applied. P precipitation using FeCl3, at the different Fe:P ratios, showed a P-recovery between 88-100 % and 57-85% in brewery and dairy wastewaters, respectively. With the addition of CaCl2, for the different Ca:P ratios, and adjusting the pH to 10, the P recovery ranged between 58-84% and 92-95% in brewery and dairy wastewaters, respectively. The experiments carried out with mussel shells (only with dairy wastewater, but for the different Ca:P ratios) demonstrated a P-recovery of 12-41%, 89-99%, and 98-99% when using raw shells, calcinated shells, and hydrated-calcinated shells, respectively. The seawater was tested in synthetic wastewater, at a 20% (v/v) ratio, showing a P recovery of 64%. In conclusion, these results demonstrate the viability of the use of alternative salt sources for P precipitation and recovery, contributing to the circular economy of agri-food industry.This study was supported by the BioEcoNorte project (NORTE-01-0145-FEDER-000070) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte and by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020info:eu-repo/semantics/publishedVersio

Assessment of mixtures of mycotoxins in cereal based foods available in Portuguese market

Mycotoxins are secondary metabolites of fungi that cause toxic and carcinogenic outcomes in humans exposed to them1. Mycotoxins affect several commodities including cereal grains and their finished products, infant formula and baby foods2. This study aimed to determine the incidence and levels of 20 mycotoxins and metabolites (AFB1, AFB2, AFG1, AFG2, AFM1, OTA, NIV, NEO, DAS, FUS-X, DON, 15-AC-DON, 3-AC-DON, HT-2, T-2, VER, T-2 TETROL, T-2 TRIOL), in breakfast cereals and cereal based baby foods available in the Portuguese market, and compare the results with the maximum limits established by the EU. Breakfast cereal samples (n=26), including corn, wheat, oat, rice and multigrain, and twenty cereal based baby foods (n=20) were collected from supermarkets in Lisbon region and analyzed by HPLC-FLD, LC-MS/MS and GC-MS. Results showed that 88 % breakfast cereals samples and 50 % of cereal based baby foods were contaminated with mycotoxins (with values above the detection limit), although all samples presented levels below the maximum limits established by the Commission Regulation 1881/20063. Regarding breakfast cereals samples, OTA and DON were the most commonly detected mycotoxins, with 88% and 73% of samples revealing values above the LOD, respectively. The co-occurrence of different mycotoxins in the same sample was observed in 92% of the analyzed samples. From these, 46% include mixtures of 3 or 4 mycotoxins. Regarding cereal based baby foods, OTA and AFM1 were the most commonly detected mycotoxins with 50% and 40% of samples revealing values above the LOD. The co-occurrence of mycotoxins was observed in 35% of the analyzed samples. These results are accordingly to those reported by Juan et al (2014)4 and Iqbal et al (2014)5. These results contribute to the increased knowledge on mycotoxin contents in cereal based foods marketed in Portugal, and they highlight the deep need of further studies to overcome the absence of legislated limits for mycotoxins in breakfast cereals other than DON and FB1 and the absence of legislated limits for mycotoxin mixtures in food. The last issue is particularly important considering the potential synergistic effects that could occur between mycotoxins and its potential impact on human and, mainly, children health.This research was performed under the MycoMix project (PTDC/DTP-FTO/0417/2012), funded by the Fundação para a Ciência e Tecnologia (FCT), Portuga

Moderate electric fields can inactivate Escherichia coli at room temperature

The inactivation of Escherichia coli using moderate electric fields (MEF) below 25 °C, was investigated. Keeping the temperature always below 25 °C demonstrated that electric fields are involved in the inactivation of E. coli, without possible synergistic temperature effects. Electric fields above 220 V cm−1 promoted death rates of 3 log10 cycles of E. coli in less than 6 min, and even higher rates at greater electric fields, while presumably overcoming the thermal degradation caused by conventional high temperature treatments. A non-thermal model was proposed that successfully describes the E. coli death kinetics under this treatment. SEM observations of E. coli cells after the exposure to the MEF treatment, revealed changes at the cell membrane level, indicating a possible cause for the cell death rates. These results show that this treatment holds potential for sterilization of thermolabile products (e.g. serum and other physiological fluids, food products), by itself or as a complement of the traditional heat-dependent techniques.The author R.C. Martins gratefully acknowledges his post-doctoral grant (SFRH/BPD/26133/2005) to the Fundação para a Ciência e Tecnologia (FCT), Portugal.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/26133/200