Simulation study on light ions identification methods for carbon beams from 95 to 400 MeV/A

Monte Carlo simulations have been performed in order to evaluate the efficiencies of several light ions identification techniques. The detection system was composed with layers of scintillating material to measure either the deposited energy or the time-of-flight of ions produced by nuclear reactions between 12C projectiles and a PMMA target. Well known techniques such as (DELTA) E--Range, (DELTA) E--E--ToF and (DELTA)E--E are presented and their particle identification efficiencies are compared one to another regarding the generated charge and mass of the particle to be identified. The simulations allowed to change the beam energy matching the ones proposed in an hadron therapy facility, namely from 95 to 400 MeV/A

Using a homogeneous equilibrium model for the study of the inner nozzle flow and cavitation pattern in convergent-divergent nozzles of diesel injectors

[EN] In this paper, the behaviour of the internal nozzle flow and cavitation phenomenon are numerically studied for non-conventional Diesel convergent-divergent nozzles in order to assess their potential in terms of flow characteristics. The used nozzles differs each other in the convergence-divergence level of the orifices but all of them keep the same diameter at the middle of the nozzle orifice. The calculations have been performed using a code previously validated and able to simulate cavitation phenomenon using a homogeneous equilibrium model for the biphasic fluid and using a RANS method (RNG k-ε) as a turbulence modelling approach. For the simulations, one injection pressure and different discharge pressures were used in order to assess the characteristics of nozzles for different Reynolds conditions involving cavitating and non-cavitating conditions. The comparison of the nozzles has been carried out in terms of flow characteristics such as mass flow, momentum flux, effective velocity and other important dimensionless parameters which help to describe the behaviour of the inner flow: discharge coefficient (Cd), area coefficient (Ca) and velocity coefficient (Cv). Additionally, the nozzles have been compared in terms of cavitation inception conditions and cavitation development. The study has shown a high influence on the results of the level of convergence-divergence used in the nozzles. In these nozzles, the vapour originated from cavitation phenomenon came from the throttle of the orifice at the midpoint, and it extended along the whole wall of the divergent nozzle part towards the outlet of the orifice. The main results of the investigation have shown how the different geometries modify the cavitation conditions as well as the discharge coefficient and effective velocity. In particular, the nozzle with highest convergence-divergence level showed cavitation for all the tested conditions while for the nozzle with lowest convergence-divergence level, the cavitation phenomenon could be avoided for high discharge pressures. Additionally, the nozzle with highest convergence-divergence level showed the lowest discharge coefficient values but similar effective injection velocity than the nozzle with lowest level of convergence-divergence level despite of its higher orifice outlet area.This work was partly sponsored by ‘‘Ministerio de Economía y Competitividad’’ of the Spanish Government, in the frame of the project ‘‘Estudio de la interacción chorro-pared em condiciones realistas de motor’’, Reference TRA2015-67679-c2-1- R. This support is gratefully acknowledged by the authors. Mr. Jaramillo’s thesis is supported by ‘‘Conselleria d’Educació, Cultura I Esports’’ of ‘‘Generalitat Valenciana’’ through the program ‘‘Programa VALI+D para investigadores en Formación’’, Reference ACIF/2015/040. The authors would like to express gratitude for the computer resources, technical expertise and assistance provided by the Universidad de Valencia relating to the use of the supercomputer ‘‘Tirant’’.Salvador, FJ.; Jaramillo-Císcar, D.; Romero, J.; Roselló, M. (2017). Using a homogeneous equilibrium model for the study of the inner nozzle flow and cavitation pattern in convergent-divergent nozzles of diesel injectors. Journal of Computational and Applied Mathematics. 309:630-641. https://doi.org/10.1016/j.cam.2016.04.010S63064130

BiFeO3/La0.7Sr0.3MnO3 heterostructures deposited on Spark Plasma Sintered LaAlO3 Substrates

Multiferroic BiFeO3 (BFO) / La0.7Sr0.3MnO3 heterostructured thin films were grown by pulsed laser deposition on polished spark plasma sintered LaAlO3 (LAO) polycrystalline substrates. Both polycrystalline LAO substrates and BFO films were locally characterized using electron backscattering diffraction (EBSD), which confirmed the high-quality local epitaxial growth on each substrate grain. Piezoforce microscopy was used to image and switch the piezo-domains, and the results are consistent with the relative orientation of the ferroelectric variants with the surface normal. This high-throughput synthesis process opens the routes towards wide survey of electronic properties as a function of crystalline orientation in complex oxide thin film synthesis.Comment: 10 pages, 4 figures, Submitted to Applied Physics Letter

Syntrophic LCFA-degrading microbial ecosystems

Long-chain fatty acids (LCFA) are energy-rich compounds, which are abundantly present in raw and waste materials. Thus, wastewaters that contain LCFA may yield high levels of methane in an anaerobic digestion process. Biogas formation from LCFAcontaining wastewater is a sustainable technology that warrants further investigation, specifically in terms of more fundamental microbiological aspects. The aim of this work is to get more insights into the syntrophic microbial communities that degrade LCFA anaerobically. Bacterial shifts of a mesophilic sludge incubated in the presence of palmitic, stearic or oleic acid was estimated by means of automated ribosomal intergenic spacer analysis (ARISA). Slightly differences were observed between the communities incubated with saturated LCFA (palmitic and stearic acids) and the ones of the blank assay. On the other hand, evident changes were found between ARISA profiles of the communities that were incubated with oleic acid and the ones obtained for the blank assay. These results suggest that the microbial communities that degrade saturated fatty acids are very close to each other and different from the ones that degrade unsaturated fatty acids

Assessment of methanogen survival in anaerobic enrichment cultures degrading long-chain fatty acids

Long-chain fatty acids (LCFA) are generally considered highly toxic towards methanogens. However, high methane yields have been obtained from high-load anaerobic digestion of LCFA, suggesting that methanogens can tolerate these compounds. In this work, hydrogenotrophic and acetoclastic methanogens were added to LCFA-degrading enrichments in order to evaluate their survival in the presence of unsaturated-LCFA (C18:1, oleate) and saturated-LCFA (C16:0, palmitate). Two hydrogenotrophs (Methanobacterium formicicum and Methanospirillum hungatei), and two acetoclasts (Methanosarcina mazei and Methanosaeta concilii) were tested. Oleate- and palmitate-enrichment cultures (OM and PM, respectively) were amended with each of the methanogens and incubated with 1 mM of the corresponding LCFA. Survival of methanogens after several transfers was evaluated by PCR-DGGE. For the hydrogenotrophs, results showed that M. formicicum survived in both OM and PM cultures, while M. hungatei only grew in the PM culture. Moreover, viability tests using live/dead staining coupled to fluorescent microscopy observation and cell counting indicated that M. hungatei is indeed more sensitive to oleate than M. formicicum. The percentage of damaged cells, caused by the exposure to low concentration of oleate (i.e. 0.5 mM), was very high in the case of M. hungatei (79%) contrasting with M. formicicum that was only slightly affected by this LCFA (8%). Regarding acetoclastic methanogens, both tested species prevailed in OM and PM cultures, although more abundant in PM enrichment. These results suggest that oleate is a more toxic compound for methanogens than palmitate. Nevertheless, all the methanogens studied, except M. hungatei, were found in the OM cultures

Double di ffential fragmentation cross sections measurements of 95 MeV/u 12C on thin targets for hadrontherapy

During therapeutic treatment with heavy ions like carbon, the beam undergoes nuclear fragmentation and secondary light charged particles, in particular protons and alpha particles, are produced. To estimate the dose deposited into the tumors and the surrounding healthy tissues, an accurate prediction on the fluences of these secondary fragments is necessary. Nowadays, a very limited set of double di ffential carbon fragmentation cross sections are being measured in the energy range used in hadrontherapy (40 to 400 MeV/u). Therefore, new measurements are performed to determine the double di ffential cross section of carbon on di erent thin targets. This work describes the experimental results of an experiment performed on May 2011 at GANIL. The double di ffential cross sections and the angular distributions of secondary fragments produced in the 12C fragmentation at 95 MeV/u on thin targets (C, CH2, Al, Al2O3, Ti and PMMA) have been measured. The experimental setup will be precisely described, the systematic error study will be explained and all the experimental data will be presented.Comment: Submitted to PR

Transductive Learning with String Kernels for Cross-Domain Text Classification

For many text classification tasks, there is a major problem posed by the lack of labeled data in a target domain. Although classifiers for a target domain can be trained on labeled text data from a related source domain, the accuracy of such classifiers is usually lower in the cross-domain setting. Recently, string kernels have obtained state-of-the-art results in various text classification tasks such as native language identification or automatic essay scoring. Moreover, classifiers based on string kernels have been found to be robust to the distribution gap between different domains. In this paper, we formally describe an algorithm composed of two simple yet effective transductive learning approaches to further improve the results of string kernels in cross-domain settings. By adapting string kernels to the test set without using the ground-truth test labels, we report significantly better accuracy rates in cross-domain English polarity classification.Comment: Accepted at ICONIP 2018. arXiv admin note: substantial text overlap with arXiv:1808.0840